Time Line Data

8/3/2019 Time Line Data

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ext Date Title Section Summary

15,000 - 10,000 BC Lascaux Cave Paintings Discoveries & Theories The oldest records of astronomical observations are 30,000 year

old cave paintings.

irca 2800 BC - 1075 B Stonehenge Tools & Technology Stonehenge is erected; its exact purpose is unknown but it is

thought to have been used for astronomical observations.

irca 2500 BC Pyramids and Plumb LinTools & Technology Early Egyptian astronomers use measuring instruments to

precisely align their pyramids.

irca 570-495 BC Pythagoras Lays the Fo Discoveries & Theories Pythagoras of Samos develops mathematical theorems used in

explaining the apparent movements of stars.

irca 500 BC Babylonian Tablet Tools & Technology Babylonian astronomers recorded their astronomical calculations

in clay tablets.

84-322 BC Aristotle Proposes Sphe Discoveries & Theories Aristotle proposes spherical Earth at the center of the universe.

irca 270 BC Aristarchus of Samos D Discoveries & Theories Aristarchus of Samos presents the first known heliocentric model

stating the sun is at the center of the universe.

irca 250 BC Eratosthenes Estimates Discoveries & Theories Eratosthenes estimates the size of the Earth.

irca 150 BC - 100 BC The Antikythera Mecha Tools & Technology The Antikythera mechanism may have been used to calculate

astronomical positions.

irca 150 BC Armillary Spheres Tools & Technology Model world systems, called armillary spheres, are built and used

as an educational tool.

150 BC The Greeks Invent the Tools & Technology The Greeks invent the astrolabe to solve spherical astronomy

problems.

150 AD Ptolemy Writes the Alm Discoveries & Theories Ptolemy writes the Almagest.

irca 632 Arabic Translations of GDiscoveries & Theories Arab astronomers begin translating Greek science and math.

00s Astronomical Observati Tools & Technology The ancient Mayan city of Palenque is believed to have been a

place for astronomical observation.

00 AD Al-Battani Devises new Discoveries & Theories Al-Battani devises new methods of calculating planetary

positions.

94 Astronomical Sextant B Tools & Technology The first astronomical sextant is built in Iran for measuring the

position of stars.

1000 The Caracol Temple in t Tools & Technology The Caracol Temple at Chichen Itza in the Yucatan Peninsula of

Mexico provides an elevated platform for astronomical

observations.

1282 Astronomical Compass Tools & Technology An astronomical compass is used for the first time in Persia

1350-1364 Astrarium Built by Giov Tools & Technology Astrarium (astronomical clock) is built by Giovanni de Dondi in

Italy.

irca 1500 Big Horn Medicine Whe Tools & Technology Big Horn Medicine Wheel is constructed by the Plains Indians in

Wyoming and used as a calendar.


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irca 1530 Alchemy Lays the Foun Discoveries & Theories Alchemy, the precursor to modern day chemistry, is most often

associated with the belief that cheap metals can be changed into

gold.

1543 Copernican Theory Discoveries & Theories Nicolaus Copernicus publishes his theory of the Solar System.

1573 Tycho Brahe Publishes Discoveries & Theories Tycho Brahe publishes De nova stella.

1585-1605 Astronomical Compendi Tools & Technology The astronomical compendium, a collection of astronomical tools

becomes popular.

1600 Giordano Bruno Burned Discoveries & Theories Giordano Bruno is burned at the stake.

1606 Johannes Kepler's De S Discoveries & Theories Johannes Kepler documents a 1604 supernova explosion in DeStella Nova.

1609 Galileo Galilei's Telesco Discoveries & Theories Galileo builds his first telescope and draws the moon.

1610 Galileo Discovers Jupite Solar System Galileo discovers Jupiter's moon Callisto

1610 Galileo Discovers Jupite Solar System Galileo Discovers Jupiter's moon Europa.

1610 Galileo Discovers Jupite Solar System Galileo discovers Jupiter's moon Ganymede.

1610 Galileo Discovers Jupite Solar System Galileo discovers Jupiter's moon Io.

1611 Kepler's Refracting Tele Tools & Technology Johannes Kepler improves upon Galileo's design of the refracting

telescope.

1615 Galileo defends Coperni Discoveries & Theories Galileo defends Copernican Theory


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1609-1619 Kepler's Laws of PlanetaDiscoveries & Theories Kepler's Publishes Three Laws of Planetary Motion.

1655 Saturn's Moon Titan Dis Solar System Titan, Saturn's largest moon, is discovered by Christiaan

Huygens.

1663 The Gregorian Telescop Tools & Technology The Gregorian telescope is designed with two concave mirrors.

1665 Newton's Prism ExperimDiscoveries & Theories Isaac Newton demonstrates that white light is made up of all the

colors that we can see.

1666 Law of Universal Gravit Discoveries & Theories Isaac Newton discovers the Law of Universal Gravitation, whichexplains the motion of the moon around the Earth and falling

bodies.

1668 Newton's Reflecting Tel Tools & Technology Isaac Newton builds the first powerful telescope without

chromatic aberration.

1672 Astronomical Unit (AU) Discoveries & Theories Giovanni Cassini improves the accuracy of the Astronomical Unit

(AU)the mean distance between the Earth and the sun.

1672 Saturn's Moon Rhea is Solar System Saturn's second largest moon, Rhea, is discovered.

1686 Newton's Three Laws of Discoveries & Theories Isaac Newton announces his Three Laws of Motion.

1704 Newton's The Opticks Discoveries & Theories Isaac Newton publishes The Opticks, describing his theories on

light composition.

1733 The Achromatic RefractiTools & Technology The achromatic refracting telescope is invented by Chester Moore

Hall.

Mid-1700s to late-1800 The Great Refracting TeTools & Technology The Great Refracting Telescopes.

1755 Formation of the Solar Discoveries & Theories Immanuel Kant proposes that the Solar System formed from a

spinning nebula and is not unique.


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mid-1700s to late-1800 The Early Reflecting Tel Tools & Technology The Early Reflecting Telescopes.

irca 1772 Oxygen Gas Discovered Discoveries & Theories Carl Wilhelm Scheele and Joseph Priestly are independently

credited with discovering oxygen.

1781 Uranus is Discovered b Solar System Uranus is the first planet to be discovered by telescope.

1789 Enceladus is DiscoveredSolar System William Herschel discovers Enceladus, one of Saturn's innermost

moons.

1796 Pierre Laplace Presents Discoveries & Theories Pierre Laplace presents his famous nebular hypothesis.

1800 Infrared Light Discover Discoveries & Theories William Herschel discovers infrared light by measuring

temperature changes in the color spectrum.

1801 Guiseppe Piazzi DiscoveSolar System Guiseppe Piazzi discovers Ceres, thought to be the eighth planetin the Solar System at the time.

1802 Pallas is Discovered andSolar System The asteroid Pallas is discovered.

1804 Juno is Discovered Solar System Juno, the third asteroid, is discovered.

1807 Vesta is Discovered Solar System Vesta is discovered and thought to be a remnant of a destroyed

planet.

1803-1808 Atomic Theory is Formu Discoveries & Theories John Dalton formulates the Atomic Theory, stating that elements

have properties and atomic weights.

1811 Avogadro's Law ConfirmDiscoveries & Theories Amedeo Avogadro links the laws of gases and chemistry,

providing a vital confirmation of the atomic nature of matter.

1814 Joseph Fraunhofer Inve Tools & Technology The spectroscope is invented by Joseph von Fraunhofer.


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1817 Fraunhofer Researches Discoveries & Theories Joseph von Fraunhofer observes dark bands that appear

throughout the spectrum of the sun.

1833 Principles of Geology ReDiscoveries & Theories Charles Lyell publishes Principles of Geology, which

revolutionizes the way scientists think about geological and

evolutionary change.

1845 Discovery of Astraea Pr Solar System Astraea is discovered and prompts the demotion of the four

original asteroids.

1846 Mathematical PredictionSolar System Mathematical predictions lead to the discovery of Neptune, the

farthest planet from the sun.

1846 William Lassell Discover Solar System 17 days after the discovery of Neptune, British astronomer

William Lassell discovers Triton, Neptune's largest moon.

1847 Hebe, Iris, and Flora ar Solar System Asteroids Hebe, Iris and Flora are discovered.

1848 1848: Asteroid Metis is Solar System The asteroid Metis is discovered.

1849 Dim Asteroid Hygiea Di Solar System The dim asteroid Hygiea is discovered.

1850 Asteroids Parthenope, VSolar System Asteroids Parthenope, Victoria, and Egeria are discovered.

1851 Asteroids Irene and EunSolar System Two asteroids, Irene and Eunomia, are discovered.

1852 Asteroids Reclassified Solar System Some early planet discoveries are reclassified as asteroids.

1859 Charles Darwin PublisheDiscoveries & Theories Charles Darwin publishes The Origins of Species introducing the

scientific theory that populations evolve through the process of

natural selection.

1862 William Thomson Estim Discoveries & Theories William Thomson estimates the age of the Earth.

1864 James Clerk Maxwell Ex Discoveries & Theories James Clerk Maxwell develops a scientific theory to explain

electromagnetic waves.

1869 Norman Lockyer Discov Discoveries & Theories Helium is discovered in space by Norman Lockyer while

observing a solar eclipse with a spectrometer.


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1930 Pluto is Discovered Solar System Pluto is discovered.

1933 Radio Waves Reported Discoveries & Theories Karl Jansky reports the reception of radio waves coming from the

center of the Milky Way galaxy.

1946 Extra-Terrestrial Obser Discoveries & Theories Spitzer proposes an "extra-terrestrial observatory" to study theuniverse in visible light.

1948 The Big Bang Theory Discoveries & Theories The Big Bang Theory explains the origin of the universe.

mid-1900s Protoplanet Hypothesis Discoveries & Theories Protoplanet hypothesis replaces the nebular hypothesis to

explain planet formation.

1950 The Oort Cloud Gets its Solar System Jan Oort proposes that certain comets come from a vast,

extremely distant, spherical shell of icy bodies surrounding the

Solar System.

1952 Origin of Life Experime Discoveries & Theories Miller and Urey conduct the origin of life experiment to examine

the kind of environment needed for life to begin.

1954 Radio Galaxies are Disc Discoveries & Theories Radio galaxies are discovered.

1955 Jupiter Radio Emissions Discoveries & Theories Radio emissions from Jupiter are detected.

1957 Sputnik 1 Launched int Tools & Technology Sputnik 1 is launched into low Earth orbit by the Soviet Union.

1959 Luna 3 Science Missions The Soviet space probe Luna 3 launches and takes the firstphotographs of the moon.

1960s Infrared Telescopes are Tools & Technology infrared telescopes are developed.

1960s-1970s X-ray Satellites Discoveries & Theories Astronomer run balloon- and rocket-borne experiments to begin

X-ray exploration of our universe from outer space.

1961 Germanium Bolometer Tools & Technology Frank Low invented a special detector of infrared radiation that

allowed observation of much longer wavelengths.

1962 Riccardo Giacconi Pione Discoveries & Theories Riccardo Giacconi proposed and built the first x-ray telescope for

flight.


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1962 Mariner 2 Science Missions Mariner 2 launches and becomes the first spacecraft to

successfully encounter another planet.

1962 Breakthrough DiscoveryTools & Technology A breakthrough discovery revolutionizes quasar observations.

1964 Cosmic Microwave Back Discoveries & Theories Cosmic microwave background radiation is discovered.

1965 The Efforts for a Large Tools & Technology The National Academy of Sciences defines the scientific

objectives for the proposed Large Space Telescope.

1966 Surveyor 1 Science Missions Surveyor 1 was the first spacecraft launched in the Surveyor

program and the first soft landing on the Moon by the United

States.

1966-1972 The Orbiting Astronomi Tools & Technology The Orbiting Astronomical Observatories are launched to study

ultraviolet and x-ray wavelengths; these are the first successful

orbiting observatories.

1968 Interstellar Chemistry Discoveries & Theories William Klemperer helps found the field of interstellar chemistry.

1968 Pulsars Discovered by J Discoveries & Theories Pulsars are discovered by Antony Hewish and Jocelyn Bell using

a special radio telescope.

1969-1972 Apollo Moon Landings Science Missions The Apollo Program was designed to land humans on the Moon

and bring them safely back to Earth. Six of the Apollo Missions

achieved this goal.

1970s Multi-mirror Telescopes Tools & Technology With the use of many individual mirrors and computers to control

them, multi-mirror telescopes emerged.

1970 Soviets Launch Venera Science Missions The Soviet spacecraft Venera 7 launches and becomes the first

spacecraft to successfully land on another planet and transmit

data back to Earth.

1971 Mariner 9 Science Missions Mariner 9 launches towards Mars and becomes the first

spacecraft to orbit another planet.

1972 Pioneer 10 Launches to Science Missions Pioneer 10 launches and is the first spacecraft to travel through

the asteroid belt to an outer planet.


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1992 1992 QB1 Discoveries & Theories The first Kuiper belt object is discovered.

1997 Fred Hoyle and Edwin S Discoveries & Theories Fred Hoyle and Edwin Salpeter are awarded the Crafoord Prize

for their pioneering contributions to the study of nuclear

processes in stars and stellar evolution.

1999 Chandra X-ray Observa Tools & Technology The Chandra X-ray Observatory launches into, it is the mostsophisticated X-ray observatory built to date.

1999 Multi-planet System Dis Discoveries & Theories Astronomers discovered the first planetary system other than

our own.

001 Wilkinson Microwave AnTools & Technology The WMAP spacecraft is launched to measure temperature

differences across the sky..

003 Hayabusa Science Missions Hayabusa is the first spacecraft to make physical contact with an

asteroid and collect surface material samples.

003 Spitzer Space Telescop Tools & Technology The Spitzer Space Telescope is launched into space detecting

infrared radiation.

004 Dwarf Planet Haumea isSolar System A dwarf planet called Haumea is discovered in the Kuiper belt.

004 MESSENGER Science Missions MESSENGER is the first spacecraft to orbit Mercury.

005 Massive Dwarf Planet DiSolar System The most massive dwarf planet, Eris, is discovered.

005 James Gunn, James Pe Discoveries & Theories James Gunn, James Peebles and Martin Rees receive the

Crafoord Prize for their contributions towards understanding the

large-scale structure of the Universe.

005 Dwarf Planet Makemak Solar System The dwarf planet Makemake is discovered in the Kuiper belt.


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006 International Astronomi Solar System The International Astronomical Union (IAU) defines what it

means to be a planet.

006 New Horizons is First Mi Science Missions New Horizons is the first mission to Pluto.

008 Rashid Sunyaev Tools & Technology Rashid Sunyaev receives the Crafoord Prize for his contributions

to high-energy astrophysics and cosmology.

008 Jerry Nelson, Raymond Tools & Technology Jerry Nelson, Raymond Wilson, and Roger Angel receive the Kavli

Prize for their contributions to the development of giant

telescopes.

008 Fermi Gamma-ray Spac Tools & Technology Fermi Gamma-ray Space Telescope is launched into a low-Earth

orbit to make gamma-ray astronomy observations.

009 Kepler Space Telescope Tools & Technology The Kepler Space Telescope launches with the hopes of

discovering other Earth-like planets orbiting other stars in theMilky Way.

011 Mars Science Laborator Science Missions The Curiosity rover will land on the surface of Mars to explore

the possibility of Mars' habitability.


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Detail

Discovered in 1940 in central France, the Lascaux cave walls are covered with drawings 16,500 years old. Among these illustrations is a

prehistoric map of the night sky showing three bright stars known today as the Summer Triangle. A map of the Pleiades star cluster has also

been found on the cave walls. The caves may have been a prehistoric planetarium where humans first charted the stars.

Mystery surrounds the intentions of the prehistoric monument Stonehenge in England. One theory is that it was built as an astronomical

observatory built in stages as a tool to track the movement of the sun, predict astronomical events such as eclipses, and mark the

solstices.

Stonehenge does have some rough alignments with the sun, but the lack of precision casts doubt on its value to advanced

astronomy at the time. There are no written records documenting its purpose.

It has been shown that Egyptians precisely aligned their pyramids and temples toward two bright stars (known as the "indestructibles") that

circled the North Pole, for star-gazing, time keeping, and religious reasons. Astronomers used plumb lines to ensure vertical alignment with

celestial objects and accurate positioning measurements between stars. By studying Egyptian hieroglyphics, picture writings, we have learned

that the ancient Egyptians had a keen interest in and solid understanding of astronomy.

Pythagoras of Samos, a Greek philosopher and mathematician, believed the Earth is a sphere in motion at the center of the universe and that

as the other planets, also spheres, travel around the Earth their movements create sounds. Stellar parallax, the illusion that certain starshave different positions in the night sky in relation to other stars depending on the time of year, is geometry that was derived from

Pythagoras. Pythagoras is most recognized for the theorem bearing his name, the Pythagorean theorem, which states that any two sides of a

right triangle or one of its sides and one of its angles can be used to determine the exact length of the other sides. He used this theorem to

calculate the circumference of the Earth.

Babylonian astronomers developed accurate mathematical formulas for predicting astronomical events and recorded them in clay tablets

known now as a Babylonian tablet. The tablets are written in ancient cuneiform script and capture concise mathematical theories capable of

predicting lunar and planetary phases and observations with impressive accuracy.

Aristotle, most famous of the Greek philosophers, proposes two reasons to believe the Earth is round. First, when a ship sails over the

horizon, the mast is visible first, then the deck, and then the entire ship. Second, the Earth's shadow on the moon during a solar eclipse is

curved, and only a spherical object could produce a round shadow. Aristotle also believed in a geocentric universe, with the Earth at the

center and the sun, stars, and other planets in orbit around it. He was well respected, and his beliefs were taught for a very long time.

Aristarchus, a Greek astronomer and mathematician, is credited with presenting the original heliocentric hypothesis of the universe, in which

the Earth revolves around the sun. His theory was based on his geometric estimates of the relative sizes and distances of the Earth, moon,

and sun. The sun was much larger than the Earth, and larger objects did not orbit around smaller objects; therefore, the sun was at thecenter of the universe. Aristarchus' arguments contradicted those of the more popular and influential Aristotle and, therefore, were not widely

accepted for another 1,800 years. A fire destroyed nearly all of Aristarchus' work.

Eratosthenes, a Greek scholar living in Egypt who made many contributions to mathematics, geography, and astronomy, is credited with the

first fairly accurate estimate of the Earth's circumference. Understanding that the Earth is a sphere, he used the sun's location overhead and

stades, the length of stadiums during that that time period, to arrive at his estimate that the Earth was 25,000 miles around.

The antikythera mechanism is essentially an analog computer built by the Greeks. It is a sophisticated instrument with 32 gears that are

believed to calculate astronomical positions and reproduce the motion of the sun and the moon.

Its exact date and origin are unknown but the armillary sphere was the primary instrument used for determining celestial positions until

telescopes were invented in the 17th century. An armillary sphere is a model of the celestial heavens where the central Earth is surrounded

by rings representing the horizon, meridian, equator, tropics, polar circles, and ecliptic hoop. In the 17th and 18th centuries variations of the

model were built to teach the difference between the Earth-centric Ptolemaic theory and the heliocentric Copernican theory. The earliest

models were simple instruments, but they grew more elaborate and sophisticated over time.

The astrolabe is an observational device that measures the elevation of the sun or star, computes latitude, sunrise and sunsets, time for

prayer, and the direction to Mecca. It was introduced to the Islamic world in the mid-eighthcentury, where its design was refined and fullydeveloped over the following centuries. The instrument peaked in popularity in Europe during the 15th and 16th centuries but was replaced

by more accurate tools in the late 17th century. The origins of the astrolabe were in classical Greek, documented in writings that were later

translated by the Arabs. Originally made from brass, their design was improved on, and more features were added to them until the Middle

Ages, by which time they had become complex instruments. Hipparchus of Rhodes was most influential in the theory of astrolabe projection

Claudius Ptolemy, the last great Greek astronomer of antiquity, wrote the Almagest, an astronomical manual made up of 13 books. The

manual contains a sophisticated mathematical model of the motions of the Solar System based on a geocentric model and the principle of

perfect circular motion. Ptolemy believed the Earth was the center of the universe, and this view was accepted for centuries. The "wheels-

within-wheels" system, as Ptolemy's model was known, was supported for more than a thousand years.

This masterpiece was

originally known by the Greek title (meaning "Mathmatik Syntaxis") until Arab astronomers translated the work to its

current title, Almagest in the ninth century.

Arab astronomers discovered many important Greek manuscripts on astronomy, science, and math and translated them into Arabic. Without

the Arab astronomers' interest and continuation of this work, Greek science might have been lost. By the early ninth century astronomical

observatories started emerging in the Muslim world.

Palenque was an ancient Mayan city dating back to 100 BC and surviving until its fall around 800 AD. Now ancient ruins, it is believed the site

may have been used for astronomical observations. A four-story tower rises out of the Palace, an immense building complex. The roofless

tower contains a Venus glyph and also provides a direct view of the sun setting over the Temple of the Inscriptions.

Al-Battani, an Islamic astronomer and mathematician, devised new methods of calculating planetary positions using trigonometry instead of

geometry, as Ptolemy did. He is also credited with accurately determining the solar year to be 365 days, 5 hours, 46 minutes, and 24

seconds. His work was fundamental to later astronomers such as Copernicus, Tycho Brahe, and Giovanni Battista Riccioli.

The first astronomical sextant was constructed in Iran for the purpose of measuring the position of the stars. Tycho Brahe refined the design

circa 1577 and used it for more accurate measurements of the angular distances between the stars.

The Caracol Temple was an astronomical observatory built by the Mayans, its architecture aligns with the appearance of the celestial bodies

Pleiades and Venus. Astronomers observed the solstice and equinox as well as stars and planetary bodies. As Mayan understanding changed

with time, the construction of new temples reflected these changes.

Al-Ashraf of Persia was the first to be documented using the compass for astronomical observations. The astronomical compass was further

developed using the Earth's magnetic field and a time-keeping mechanism to calculate the direction of Mecca and indicate the time for daily

prayers.The first documented astrarium, astronomical clock, was built by Giovanni de Dondi in Italy. Also known as a planetarium, an astronomical

clock is a complex mechanism consisting of 107 gear wheels, a calendar wheel and 7 dials showing positional data for the sun, Mars, Jupiter,

Saturn, the moon, Mercury, and Venus. It provided a continuous display of the major elements of the Solar System along with religious and

civil calendars of that time. The clock was intended to help people understand astronomical and astrological concepts. Built entirely by hand

and marveled for its craftsmanship, it was installed in the Duke's castle in Pavia, Italy until at least 1485, but its whereabouts are now

unknown.

Big Horn Medicine Wheel is located in the Bighorn National Forest in Wyoming on Medicine Mountain at an elevation of approximately

10,000 feet. The medicine wheel has a diameter of 75 feet and an arrangement of rocks resembling a 28-spoke wheel; the Indians used it as

a calendar. The 28 spokes represent the 28 days of the lunar cycle. It is believed that the spokes could be pointing to certain stars or to the

sunrise or sunset at a certain time of year, indicating the wheels were a way to mark certain days of the year such as the solstice.


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Alchemy is a medieval science that was primarily concerned with turning cheap metals and alloys into gold and in helping people live longer

by creating a special concoction called the "elixir of life." Paracelsus (1493-1541) was a Renaissance physician, alchemist, and astrologer who,

although he practiced the basic principles of alchemy, rejected magical philosophies. Instead, he focused his knowledge on helping the sick by

advancing the field of medicine. He pioneered the use of chemicals and minerals in medicine.

While alchemy was based largely on

experimentation, its instruments and theories regarding altering the properties of compounds and elements paved the way for modern

chemistry.

Nicolaus Copernicus (1473-1543), a Polish astronomer and mathematician, published De Revolutionibus Orbium Coelestium (On the

Revolutions of the Celestial Spheres), which is often regarded as the starting point of modern astronomy. His heliocentric model, with the sun

at the center of the universe, demonstrated that the observed motions of celestial objects could be explained without putting the Earth in the

center of the universe. Instead, all planets, including Earth, moved in circles, one inside the other, orbiting the motionless sun. Mercury and

Venus have the smallest circles and are always closer to the sun than Earth and the other planets.

Copernicus initially resisted

openly publishing his views, not wishing to risk the scorn he would have exposed himself to on account of the novelty and incomprehensibility

of his theses. His views opposed common Christian beliefs of the time, and his book was banned by the Roman Catholic Church until 1835.

In 1573, Tycho Brahe (1546-1601), a Danish nobleman with a keen interest in astronomy, published De Nova Stella (Of the New Star) based

on his observation of a very bright star in the constellation Cassiopeia. This launched his career and reputation in astronomy, and the king of

Denmark gave him the island of Hveen on which to build his own astronomical observatory. Tycho is most famous for his precise and

comprehensive astronomical and planetary observations. Working before the invention of the telescope, he was also known for the

instruments he designed, built, and calibrated. His extensive and accurate observations led to Kepler's laws of planetary motion.

An astronomical compendium is a collection of devices used for telling time and performing astronomical calculations. The compendium

typically includes a sundial, a compass, tables of latitudes, tables of star positions, a perpetual calendar, lunar and solar volvelles (wheel

charts showing phases of the moon and positions of the planets) and an astrolabe.

On February 16, 1600, Italian monk and astronomical author Giordano Bruno (born in 1548) was burned at the stake by civil authorities after

the Roman Inquisition found him guilty of heresy for his cosmological theories. Bruno was convicted and sentenced to death because he

championed the Copernican theory that the Earth was not at the center of the universe and because he taught that Earth was not unique in

the vastness of space. Bruno's theories also proposed that the sun was merely a star and the universe was infinite.

In October 1604, a bright new star suddenly appeared in the constellation Ophiuchus. Johannes Kepler (1571-1630), a German astronomer

and mathematician, observed the new star for 17 months until it faded from view in 1606. In De Stella Nova (The New Star), Keplerdocuments his observations and is greatly impressed by the new star because it coincided in time and place with a triple conjunction of the

planets Mars, Jupiter, and Saturn. In the 1940s scientists determined the object was an exploded star, and they called it Kepler's supernova.

This was the last supernova seen in our galaxy.

In 1609, Galileo Galilei (1564-1642), an Italian physicist and astronomer, built his most famous invention a telescope made from lenses he

ground himself. He modeled his design after other telescopes in Europe but with enhanced magnification of up to 20 times. In 1609, he

observed the craters on the moon for first time and documented his observations in drawings for the world to see. Additionally, he observed

sunspots, the four satellites around Jupiter, and the phases of Venus, from crescent to full, which are similar to those of our moon, which

could only be explained by the Copernican Theory.

Discovered: January 7th, 1610
Classification: Moon
Composition: Rock and ice
Potentially Habitable

Callisto is the

outermost of the Galilean moons and orbits outside of Jupiter's main radiation belts where it is less affected by Jupiter's magnetosphere. With

a diameter of more than 4,800 kilometers, Callisto is the third largest satellite in the Solar System; 99 percent the diameter of Mercury but

only a third of its mass. Callisto is heavily cratered with minimal geologic activity on its surface. It is the oldest landscape in the Solar

System, with a surface age of about 4 billion years.

As with the other Galilean moons, the discovery of Callisto orbiting around

Jupiter lent support to the heliocentric model of the universe with planets orbiting around the sun.Discovered: January 8th, 1610
Composition: Rock

Originally observed by

Galileo on January 7th, 1610, Europa appeared as a merged point of light including Io. It took a separate observation the following day to

note the existence of two separate bodies. Europa has a very circular orbit that carries it on average 670,900 kilometers from Jupiter, and it

orbits the planet in a little more than 3 days. Compared to Earth's moon, Europa is slightly smaller, with a diameter of 3,138 kilometers,

and many scientists believe it to be covered almost entirely by a subsurface frozen salt water ocean. A phenomenon known as tidal heating

causes Europa to be warm enough to potentially support the survival of simple organisms within its ocean if they exist. Europa is believed to

be one of the most likely Solar System locations in terms of potential habitability.


Discovered by

Galileo on January 7, 1610, Ganymede is the largest moon in our Solar System; if it orbited the sun instead of Jupiter it would be classified as

a planet. Its magnetic field is embedded within Jupiter's massive magnetosphere. Spacecraft images indicate Ganymede's surface is a mixture

of ancient highly cratered dark regions and younger lightly grooved terrain that was likely caused by the release of water from beneath the

surface.

As with the other Galilean moons, the discovery of Ganymede orbiting Jupiter lent support to the heliocentric model of the

universe, with the planets orbiting the sun.

Composition: Rock

Io is one of the four

Galilean moons orbiting around Jupiter. The fourth largest moon in our Solar System, Io has a diameter of 3,642 kilometers. It is the

innermost of the Galilean moons, exposing it closely to Jupiter's powerful magnetosphere and ambient radiation. Due to tidal heating from its

orbit around Jupiter, Io is one of the most geologically active bodies in the Solar System, expanding and contracting with tidal forces and

covered with more than 400 volcanoes. Data indicates that that Io might have its own magnetic field.

The discovery of Io played a

significant role in astronomy: it supported the heliocentric model of the universe, furthered the development of Kepler's Laws of Motion, and

played a role in the first measurement of the speed of light.

Johannes Kepler studied optics and understood how glass could be used to focus light. He suggested changing the shape and placement of the

lens inside the telescope, replacing Galileo's concave lens with a convex lens, which resulted in a larger viewing area. Kepler was also able to

produce a crisper image by modifying the spherical shape of the lens with a more gradual curve. He also located the lens further apart,

creating a longer telescope than Galileo's (some refracting telescopes were more than 100 feet long!). However, Kepler was not able to solve

the chromatic aberration issue with the bright objects.

The Inquisition received a complaint about the writings of Italian physicist and astronomer Galileo Galilei (1564-1642), arguing that he

supported the Copernican theory, a heliocentric view of the universe that placed the sun motionless at the center of the universe with Earthand the other planets in circular orbits around it. Galileo traveled to Rome in 1615 to defend himself against the accusations and to persuade

the Church not to prohibit support of the Copernican theory. Galileo was successful in his defense but failed to influence the Church's views in

support of Copernican theory.

In 1616 the Inquisition declared it heresy to support the theory of the sun being at the center of the

universe or the Earth moving in orbit. Cardinal Bellarmine summoned Galileo to Rome to warn him that it was now prohibited to teach,

support, or defend the Copernican theory. Although he was not charged with a criminal offense at that time, Galileo was told he could not

discuss his theory orally or in writing.

Galileo traveled to Rome to ask Pope Urban VIII to withdraw the 1616 prohibition of

Copernican theory. The Pope gave Galileo permission to write about and discuss Copernican theory under the condition that he treat the


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Johannes Kepler (1571-1630), a German astronomer and mathematician was one of the most important astronomers in history. Kepler was

influenced by Brahes observations and by the Copernican theory of the Earth revolving around the sun in his research on planetary motion.

In 1609 he published two of his three laws of planetary motion followed by the third in 1619. Kepler's Three Laws of Planetary Motion are:

planetary orbits are ellipses with the sun at one focus;a line joining a planet to the sun sweeps over equal areas in equal

time intervals; and the square of the orbital period of a planet is directly proportional to the cube of its average distance from the

sun (the time it takes for a planet to orbit the sun increases with the radius of its orbit).

Discovered: March 25, 1655 Classification: Moon

Titan, Saturn's largest

moon, was discovered by Christiaan Huygens in 1655. Titan is of great interest to scientists because it is the only moon in the Solar System

known to have clouds and a mysterious, thick, planet-like atmosphere. In 1980, Voyager 1 spacecraft tried to take close- up images of the

natural features of Titan''s landscape, but was unable to penetrate the thick clouds. Titan''s atmospheric pressure is about 60 percent greater

than the Earth''s -- roughly the same pressure found at the bottom of a swimming pool. Its atmosphere might consist of compounds similar

to those present in the primordial days of the Earth''s atmosphere.

Data from the Cassini-Huygens spacecraft (currently orbiting

Saturn) should shed new light on Titan's mysteries. During dozens of fly-bys, the Cassini orbiter is mapping Titan with cloud-penetrating

radar and collect atmospheric data. The Huygens probe dove through Titan's dense atmosphere with instruments capable of analyzing its

components.

The Gregorian telescope is a reflecting telescope designed by James Gregory and first built by Robert Hooke. It was designed before Newton's

telescope, but it wasn't successfully built until 1672. The Gregorian telescope uses two concave mirrors; the first one collects light and brings

it to focus before it strikes the second mirror where it is reflected back through a hole in the center of the first lens and then out the bottom

of the instrument where it can be viewed through an eyepiece. This design eliminated the chromatic aberration and improved on the fuzzy

image quality in refracting telescopes.

Isaac Newton (1642- 1727), an English physicist, mathematician, alchemist, and astronomer, was a science student at Cambridge University

in England when he was inspired by a simple beam of light and a glass prism. Newton placed a glass prism in a lone beam of sunlight that

streamed through a hole in his window shutter. As the sunlight entered the prism, a multicolored band of light, a color spectrum, streamed

out the other side. Newton predicted that all of those colors were present in the beam of sunlight and proved his theory by passing the

spectrum through a second prism where the colors combined back into white sunlight. This experiment was documented and expanded upon

in Newton's The Opticks in 1704.

Isaac Newton (1642-1727), an English physicist, mathematician, alchemist, and astronomer, stated in his Law of Universal Gravitation that

every particle of matter in the universe attracts every other particle with a force directly proportional to the products of their masses andinversely proportional to the square of the distance between them. The force of gravity between two objects depends on the masses of those

objects and the distance between their centers. The greater an object's mass, the greater its gravitational force. Additionally, as the distance

between two objects increases, the gravitational force between them gets smaller. As an object moves further away from Earth's center, the

gravitational force between those objects decreases.

Newton was studying optics when he developed the first reflecting telescope in 1668. He replaced the glass lens from the refracting telescope

with a metal mirror constructed of six parts copper and two parts tin. The mirrors reflected more light and improved the viewable area. The

chromatic aberration problem of refracting telescopes wasn't an issue in his design because light rays weren't passing through glass and

producing a halo around bright objects. However, Newton's telescope didn't solve the clarity issue that was due to spherical lenses. It wasn't

until 1721 when John Hadley had the technology to grind a nonspherical lens that this issue was resolved.

AU is the average distance between the Earth and the sun. It is a derived constant used to indicate distances within the Solar System. The

Earth orbits the sun at a distance of 1 AU.

Tycho Brahe (1546-1601), a Danish inventor and author of De Stella Nova, estimated the

AU to be 5 million miles. German astronomer Johannes Kepler (1571-1630) estimated it to be 15 million miles. In 1672 Giovanni Cassini

(1625-1712), an Italian/French mathematician and astronomer, improved the accuracy of the AU by observing Mars. While Cassini observed

Mars from Paris, his colleague Jean Richer observed Mars at the same time in South America. From these observations, Cassini determinedthe parallax of Mars, which he used to calculate the distance from Earth to Mars and then the distance from the Earth to the sun. Cassini

calculated the AU to be 87 million miles, slightly less than today's calculation of approximately 93 million miles.

Discovered: December 23, 1672
Composition: Ice and rock

Rhea is Saturn's

second largest moon, and it was discovered by Giovanni Domenico Cassini on December 23, 1672. It is a small, cold, airless body. Based on

its low density and Cassini spacecraft measurements, scientists believe the moon is composed of 75 percent ice and 25 percent rock a

frozen, dirty snowball. Rhea appeared as a tiny dot to astronomers until the Voyager (1 and 2) encounters in 1980 and 1981. The

Voyager images showed that Rhea's features could be divided into two regions: heavily cratered terrain with craters larger than 40 kilometers

(25 miles) across and a second type of terrain with smaller craters in parts of the polar and equatorial region. The Voyager images also

showed mysterious linear "wispy" lines tens to hundreds of kilometers long, often cutting steep walls of cliffs indicating the likelihood of

tectonic activity. Newer Cassini images of Saturn's moon Rhea have revealed dramatic fractures cutting through craters on the moon's

surface. These findings are helping astrobiologists understand the processes that occur on moons of giant planets and could help identify

Isaac Newton (1642-1727), an English physicist, mathematician, alchemist, and astronomer, developed the theory of gravitation in 1666, and

in 1686 he shared his new insights into motion the Three Laws of Motion, where the popular phrase "to every action there is always an

equal and opposite or contrary reaction" comes from.
The law of inertia: An object at rest will remain at rest unless acted on

my an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an

unbalanced force.F = m * a: Acceleration is produced when a force acts on a mass. The greater the mass (of the accelerating

object) the greater the amount of force needed to accelerate it.For every action there is an equal and opposite reaction. When an

object pushes another object it gets pushed back in the opposite direction with equal force.

As early as the mid-1600s, Isaac Newton was researching light composition and the color spectrum. His prism experiment is documented in

this book, where he presents detailed observations on his discovery of spectrum light and spectral analysis. Newton's theories were held in

high regard until the introduction of the wave theory of light in the early 19th century.

Chester Moore Hall was a lawyer with an interest in lenses and their possible uses. The achromatic lens creates a better image than the

lenses found in the first refracting telescopes. The original lenses refracted light at different angles based on the light's wavelength, or color,

which caused chromatic distortion. The achromatic lens focused and corrected these color distortions.

By the middle of the 1700s astronomers had more knowledge about the property of light and the behavior of optics than ever before. Chester

Moore Hall conducted experiments using different types of glass for the primary and secondary lenses to eliminate the chromatic aberration.

John Dolland expanded on Hall's technique and refined the curve of the lenses to eliminate the spherical aberration (fuzzy image quality) of

early refracting telescopes. By the early 1800s, Pierre Louis Guinand and Joseph von Fraunhofer began casting glass for lenses in order to

create larger pieces of glass that were free of flaws and refracted light more uniformly. This new technology was combined with photography,

providing astronomers with the means of accurately recording their observations. These improvements led to more powerful telescopes that

became more popular than reflecting telescopes until the 1890s.

Immanuel Kant (1724-1804), a philosophy professor in Prussia, was the first to hypothesize that the Solar System was formed when a

nebulae, a group of gaseous clouds, gradually collapsed under gravity into a flat, rotating disk that eventually turned into stars and planets.

He also spoke of the possibility that our Solar System might exist among other similar Solar Systems or transforming nebulae and disks.

Astronomers began expanding their research beyond our Solar System to the extragalactic.

The Solar Nebular Disk Model is a widely

accepted modern variant of Kant's theory.


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Metal mirrors in telescopes reflected light (as opposed to glass lenses, which refracted light), which allowed astronomers to build shorter and

more powerful telescopes that were easier to maneuver. Technology and machine advancement in 18th century Europe led to the

development of the parabolic mirror, which eliminated the blurry images caused by spherical aberration. As it became easier to make bigger

mirrors, reflecting telescopes also got bigger; the bigger the mirror, the more light it could collect, which improved the observation quality of

further and dimmer objects. In the 1770s, William Herschel, motivated to build a telescope that was easier to handle than the refractors,

began experimenting with mirrors and came up with an improved alloy that reflected more light. With larger and more powerful mirrors he

could build bigger telescopes, the largest being 40 feet long with a 48-inch diameter mirror.

In 1772 or 1773, Carl Wilhelm Scheele (1742-1786), a German-Swedish chemist, discovered oxygen by heating mercuric oxide with various

nitrates. Calling his discovery "fire air," Scheele didn't publish his findings until 1777. Meanwhile, in 1774, Joseph Priestly (1733-1804), a

clergyman, focused sunlight on mercuric oxide and discovered a gas he called "dephlogisticated air." This gas was later named "oxygen" by

Antione Lavoisier, and its discovery led to a more sophisticated understanding of chemical reactions and is considered to have launched

chemistry forward out of the middle ages.

Discovered: March 13, 1781
Classification: Planet
Composition: GasHabitable:

NoSir William Herschel discovered Uranus on March 13, 1781; it was the first planet discovered by telescope. It is visibleto the naked eye, but ancient astronomers didn't recognize it as a planet because of its dimness and slow orbit it takes 84 years to orbit

the sun. Uranus has dramatic dark, narrow rings and 27 moons. This giant planet, 14 times larger than earth, is a faint bluish color because

the methane gas in its atmosphere absorbs red light and reflects blue light. Uranus is the seventh planet from the sun and the coldest planet

in our Solar System. The most extraordinary feature about Uranus is its extreme tilt; the planet rotates on its side.

Voyager 2, the

only spacecraft to visit Uranus, imaged a bland-looking sphere in 1986. When Voyager flew by, the south pole of Uranus was pointed almost

directly at the sun because Uranus was near its southern summer solstice, with the southern hemisphere bathed in continuous sunlight and

the northern hemisphere radiating heat into the blackness of space.

Discovered: August 28, 1789
Composition: Mainly ice

Enceladus displays at

least five different types of terrain: craters, fissures, plains, corrugated terrain, and other crustal deformations. All of this indicates that its

interior may be liquid, even though it should have frozen ages ago. Enceladus reflects almost 100 percent of the sunlight that strikes it,

resulting in a surface temperature of -330 Fahrenheit.

The Cassini spacecraft has done several fly-bys of Enceladus; in 2005 the fly-

by revealed greater detail about the moon's environment and surface and indicated it is geologically active today. Plumes emitting water-ice

on the moon's surface were present with complex organics indicating the environment could potentially support life. Active eruptions have

been observed, and analyses of those gases suggest sodium salts and subsurface liquid water exist. This unique chemistry makes Enceladusimportant in the study of astrobiology.

Pierre Laplace (1749-1827), a French astronomer and mathematician, expanded on Kant's nebular hypothesis in 1755. His proposal differed

from Kant's in that he believed planet formation occurred when rings of matter split off a rotating nebulae by centrifugal force. Once the

matter split off, it formed a planet and additional planets were created as the process repeated itself. The sun grew out of the left over

matter.

William Herschel (1738-1822), a German and British astronomer, conducted an experiment to measure the temperature differences between

the different colors in the visible spectrum. He observed that the temperature increased from blue to red with the highest temperature just

beyond the red portion, where there was no visible color. Herschel had discovered there is light we cannot see beyond the visible spectrum;

this light was later called "infrared." Infrared energy is often detected by temperature; it can reveal objects in the universe that cannot be

seen with our eyes alone or with optical telescopes. In the 1950s, astronomers began using lead-sulphide detectors to study infrared

radiation.

Discovered: January 1, 1801
Classification: Dwarf Planet

Guiseppe

Piazzi was searching the skies for a star but instead found a moving star-like object that he first thought was a comet. He reported his finding

as a comet but "since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better thana comet." Johann Elert Bode believed Ceres was a missing planet between Mars and Jupiter so Ceres was assigned a planetary symbol and

remained classified as a planet for nearly half a century.

Although it was first considered to be a planet, as were other early

asteroids, Ceres was referred to as an asteroid, meaning "star-like," when William Herschel came up with the term to describe this new class

of space object. These objects were officially reclassified as asteroids in 1852 after several others had been discovered. Ceres was reclassified

again in 2006 as a dwarf planet. The potential presence of water ice has lead some scientists to hypothesize that life may exist there.

Classification: Asteroid

Heinrich Olbers discovered Pallas on March 28, 1802, when he was trying

to locate Ceres and Pallas was passing near Ceres. Pallas appears to be the third-largest object in what is now known as the asteroid belt. Its

unusually high orbit and large orbital eccentricity make Pallas relatively inaccessible to spacecraft.

In 1802 William Herschel coined

the term "asteroid" for such bodies; "they resemble small stars so much as hardly to be distinguished from them, even by a very good

telescope." Ceres and Pallas were officially reclassified as asteroids in 1852 after several others had been discovered.

Discovered: September 1, 1804
Classification: AsteroidKarl Harding discovered the asteroid Juno on September 1, 1804. It is

one of the largest objects in the asteroid belt. Juno was originally considered a planet along with other asteroid discoveries at the time; in

1852 these were all reclassified as asteroids as more were discovered. Because of its small size and irregular shape, Juno was never

considered for dwarf planet classification.

Classification: Asteroid Vesta was discovered on March 29, 1807, by Heinrick Olbers and was

initially thought to be the remnant of a destroyed planet. Vesta was the fourth object to be identified in the region now known as the main

Asteroid Belt. It is the brightest and second-most massive object in the Asteroid Belt. Vesta was the last discovery of a celestial object for the

next 38 years.

John Dalton (1766-1844), an English chemist, meteorologist and physicist, was the pioneer behind the atomic theory. The theory gave

scientists a new way to explore the physical world and the chemical compositions of matter. Matter is composed of tiny invisible

particles called atoms.All atoms of one element are identical to one another but different from the atoms of other

elements.Chemical reactions consist of rearranging atoms in simple, whole-number ratios.With this new information on

atomic weights, a Russian chemist developed the periodic table of the elements, which led to the discovery of new elements. Dalton's atomic

theory remains relevant in modern chemistry.

Amedeo Avogadro (1776-1856), an Italian physicist and lawyer, was building off of John Dalton's atomic theory when he suggested

Avogadro's Law. Volume increases as the number of particles increases if temperature and pressure stay constant; likewise, volumedecreases as the number of particles decreases if temperature and pressure stay constant. Our lungs are an example of Avogadro's Law: as

we breathe in oxygen our lungs expand and fill with gas particles, and they contract as we exhale and expel the gas particles.

Joseph von Fraunhofer (1787-1826) invented the spectroscope (or spectrometer) in 1814. This instrument is used by astronomers to

measure properties of light emitted by celestial objects by breaking the light into its component wavelengths. The data is plotted so

researchers can analyze the chemical structures in the light and compare them to the other known elements in an effort to understand the

composition of objects in the Solar System. One remarkable discovery in astronomy is that the stars are made up of the same kind of atoms

that are here on Earth.


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Joseph von Fraunhofer (1787-1826), a German physicist, did extensive research on the phenomenon of spectral lines, which came to be

known as Fraunhofer lines or absorption lines. Expanding on Newton's prism experiment, Fraunhofer discovered dark lines scattered

throughout the color bands, which indicated segments of colors were missing from the spectrum. These dark lines are visible in the solar

spectrum when sunlight travels through a prism and is separated into bands of color. The lines occur when the cooler gas, which is higher in

the sun's atmosphere, absorbs some colors of the light emitted by the hotter gas lower in the sun's atmosphere.

Fraunhofer lines

have been important to astronomers because precise measurements of the wavelengths of missing colors (Fraunhofer lines) and knowing how

much light is absorbed gives us information about the temperature and chemical composition of the sun and other stars.

Charles Lyell (1797-1875) was a British geologist who popularized James Hutton's concepts of uniformitarianism the thought that the Earth

was shaped slowly over time by major geological forces of nature still in operation today. Examples of such forces are volcanoes, earthquakes,

and erosion. The central element to Lyell's theories is that over extremely long periods of time even relatively slow-acting forces such as wind

erosion can have an enormous influence on the Earth's surface as opposed to its having been shaped solely by more sudden, catastrophic

events. This concept challenges the Bible's theory of a young Earth that is only about 6,000 years old. Charles Darwin read Lyell's book during

his passage on the HMS Beagle and was convinced that the book presented the correct interpretation of the Earth's geological history.

Principles of Geology was critical to Darwin's research on biological evolution. During his excursion, Darwin spent five weeks in the Galapagos

Islands and began to develop a clear understanding of plant and animal evolution.

Discovered: December 8, 1845
Classification: AsteroidKarl Hencke, an amateur astronomer and post office employee, was

looking for Vesta 4 when he observed Astraea on December 8, 1845. After the discovery of Astraea, thousands of other asteroid discoveries

followed.

The discovery of Astraea triggered the eventual demotion of the four original asteroids (Ceres, Pallas, Vesta, and Juno)

from their status as planets.

Discovered: September 23, 1846
Classification: Planet
Composition: Gas Habitable:

No Galileo's drawing indicates he observed Neptune back in 1612 but presumed it was a fixed star. Neptune had just gone

into a state of retrograde (the apparent backward motion created when the orbit of the Earth takes it past an outer planet) and thus appeared

motionless through Galileo's telescope. When Uranus didn't travel exactly as astronomers expected it to, a French mathematician, Urbain

Joseph Le Verrier, proposed that the position and mass of another as yet unknown planet could cause the observed changes to Uranus' orbit.

Le Verrier sent his predictions to Johann Gottfried Galle, and Galle found Neptune on his first night of searching in September of 1846.

Seventeen days later, its largest moon, Triton, was also discovered.

In 1989, Voyager 2 became the first and only spacecraft to do

a fly-by of Neptune; it imaged clouds casting shadows on a lower cloud deck, enabling scientists to visually measure the altitude differences

between the upper and lower cloud decks. Voyager 2 confirmed the existence of Neptune's 6 rings and discovered 6 of its 13 knownDiscovered: October 10, 1846
Composition: Rock

Seventeen days after the

discovery of Neptune, British astronomer William Lassell discovered Triton, Neptune's largest moon. Triton is the largest of Neptune's 13

moons. It is unusual because it is the only large moon in our Solar System that orbits in the opposite direction of its planet's rotation a

retrograde orbit. Scientists think Triton is a Kuiper Belt object captured by Neptune's gravity millions of years ago. It shares many similarities

with Pluto, the best known world[CCS2] of the Kuiper Belt.

Voyager 2, the only spacecraft to fly past Neptune and Triton, found

Triton has active geysers, making it one of the few geologically active moons in our Solar System. Triton is one of the coolest objects in our

Solar System so cold that most of its nitrogen is condensed as frost, giving its surface an icy sheen that reflects 70 percent of the sunlight

that hits it. The possible presence of a layer of liquid water suggests the possibility, if unlikely, of life.

Discovered: 1847
Classification: AsteroidHebe is a high bulk density asteroid discovered by Karl Hencke on July 1, 1847. Iris

is a very bright asteroid located near the sun. It was discovered on August 13, 1847 by John Hind. Flora, a large, bright asteroid, is the

innermost large asteroid to the sun; no closer asteroid is as big. Flora was discovered on October 18, 1847, by John Hind.

Discovered: April 25, 1848
Classification: AsteroidMetis, discovered by Andrew Graham on April 25, 1848, is one of the larger

asteroids in the main Asteroid Belt and may be the core remnant of a larger asteroid that was destroyed in an ancient collision.

Discovered: April 12, 1849
Classification: Asteroid Hygiea, an oblong asteroid with low density, was discovered by Annibale deGasparis on April 12, 1849. It is relatively far from the sun so it appears very dim when viewed from Earth.

Discovered: 1850
Classification: AsteroidOn May 11, 1850, Annibale de Gasparis discovered the asteroid

Parthenope.

Victoria is a large and elongated asteroid that was discovered on September 13, 1850 by John Hind. It is suspected to

be a binary asteroid, that is, a system of two asteroids orbiting a common center of mass.

Egeria was discovered on November 2,

1850 by Annibale de Gasparis. Spectral analysis indicates Egeria has unusually high water content, making it a candidate for future water-

mining missions.

Discovered: 1851
Classification: Asteroid Discovered on May 19, 1851, by John Hind, Irene is a very large asteroid. Eunomia

is also a very large asteroid, and it was discovered by Annibale de Gasparis on July 29, 1851. Eunomia has attracted a moderate amount of

scientific attention, in part because it contains slightly more than 1 percent of the mass of the entire main belt.

Beginning back in 1801 there were a number of new planet discoveries including Ceres, Pallas, Juno, Vesta, and Astraea that initially

appeared as stars but after observation were found to be moving. Their rocky bodies were smaller than other planets, and astronomers came

to believe asteroids are objects that failed to coalesce into planets because of the gravitational pull of Jupiter. Most asteroids are located

between the orbits of Mars and Jupiter in what is now referred to as the Asteroid Belt.

Charles Darwin's The Origins of Species (the full title is On the Origin of Species by Means of Natural Selection, or the Preservation of

Favoured Races in the Struggle for Life) is considered to be the foundation of evolutionary biology. One of the most controversial books

of the 19th century, the theory is widely accepted by modern scientists, yet it is banned in some schools. Drawing on his research during the

Beagle expedition and George Lyell's work, Principles of Geology, Darwin argues that evolution of a species occurs because of natural

selection. The Origins of Species explains how the geological record uses patterns of sedimentation, erosion, and fossil patterns to document

the slow process of natural selection. The pace of evolutions also depends on variability and changes in the environment.

The

Origins of Species is still a landmark work in the field of evolutionary biology.

The physicist William Thomson (dates??) (later Lord Kelvin) published calculations that estimated the age of the Earth

at between 20 million and 400 million years. Thomson's calculations were based on mathematical modeling of the Earth cooling and direct

measurements of thermal gradients. Many geologists did not accept that the Earth was so young, stating that the Earth was of an indefinite

age. Charles Darwin and other biologists also disagreed with Thomson, arguing that the Earth had to be much older in order to support their

theory of the slow natural selection project of evolution and biological diversity. In 1897 Thomson revised his estimate of the Earth's age

thus: it was "more than 20 and less than 40 million years old, and probably much nearer 20 than 40."

James Clerk Maxwell (1831-1879), an English scientist, discovered that electrical fields and magnetic fields can couple together to form

electromagnetic waves. Neither electrical fields nor magnetic fields can travel anywhere by themselves, but Maxwell observed that a changing

electrical field will induce a changing magnetic field, and vice versa. Changing electricity, in short, produces magnetism, and changing

magnetism produces electricity.

Maxwell's theory summarized everything known at the time about electricity and magnetism into

mathematical formulas known as Maxwell's equations, and these became commonly known as the theory of electromagnetism.

Electromagnetism is one of four fundamental forces that control everything happening in our universe.

Norman Lockyer (1836-1920), an English scientist and astronomer, was interested in electromagnetic spectroscopy and how it could be used

for studying the composition of the universe. Lockyer adapted his telescope to use a spectroscope for observations of the outer solar

atmosphere, what he referred to as the Chromosphere. He realized the spectral lines did not correspond with known elements; this new

yellow line had not been previously identified. This was the discovery of a new element he named Helium after the Greek word "helios"

meaning "sun." It was the first time a new element was identified in space before here on Earth.


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Discovered: February 18, 1930
Classification: Dwarf Planet
Composition: Rock and IceHabitable:

No At one time considered to be the ninth planet, Pluto is now recognized as a dwarf planet and the largest member of

the Kuiper belt, after an August 2006 IAU definition that required planets to have orbital paths free of debris. Clyde Tombaugh discovered

Pluto in 1930, using a set of photographs taken two weeks apart and a machine known as a blink comparator. Pluto was given its name by an

11-year-old schoolgirl in honor of the Roman god of the underworld. On average, Pluto occupies an orbit of roughly 6 billion kilometers from

the sun, and it has a temperature that varies between -235 and -210 Centigrade. Due to its highly eccentric orbit, Pluto comes closer to the

sun at times than Neptune does. Pluto has three known natural satellites, Charon, Nix, and Hydra. The NASA New Horizons spacecraft

launched in 2006 will reach Pluto in 2015.

Karl Jansky (1905-1950), an American physicist, detected radio noise coming from the Milky Way. Jansky determined the noise was celestial

in nature as opposed to terrestrial because the signal strength varied based on the Earth's rotation.

Radio waves are relevant in the

astronomical discovery of pulsars, plasma clouds, and quasars. Celestial objects that have a magnetic field usually produce radio waves.

STEREO satellite, for example, monitors bursts of radio waves from the sun's corona. Likewise, wave sensors on the WIND spacecraft monitor

the radio waves of a planet's ionosphere.

Lyman Spitzer, Jr. (1914-1997), an American theoretical physicist and astronomer, spoke about the need for an "extra-terrestrial

observatory" so the universe could be studied in visible light. Spitzer proposed that an observatory be put in space where it could detect a

wide range of wavelengths without interference from our atmosphere. His idea was that using a telescope above Earth would give scientists

the ability to see the universe with superior clarity. Spitzer authored Astronomical Advantages of an Extra-Terrestrial Observatory, describing

his plans and their benefits in great detail and then spent the next 50 years working on his vision.

Spitzer was awarded the 1985

Craaford Prize for his studies of the interstellar medium.

The Big Bang theory is a widely accepted theory for the origin and evolution of our universe. It speculates that 12 to 14 billion years ago the

universe began its existence as a dense, hot mass only a few millimeters long that exploded, releasing all of the known matter and energy in

the universe. In a split second the universe expanded from its miniscule origin to astronomical scope and has continued to expand ever since.

It isn't fully understood, but scientists believe that as the universe has expanded it has also cooled, and with this cooling denser atoms form

and gradually condense into stars and galaxies.

The Big Bang Theory is based on the calculations of astronomers Ralph Alpher and

George Gamow in the 1940s. Hans Bethe also contributed to related theories.

Carl von Weizsacker (1912-2007) and Gerard Kuiper (1905-1973) arrived independently at the same hypothesis of planet formation. They

believed the Solar System began to form when nebulae collapsed and fused into dense masses. These masses collided and formed

protoplanets. The sun emerged from an expanding mass hot enough to radiate energy and solar winds control the remaining gasses.In 1950 Dutch Astronomer Jan Oort (1900-1992) proposed that certain comets come from a vast, extremely distant, spherical shell of icy

bodies surrounding the Solar System. This giant swarm of objects is now known as the Oort cloud, occupying space at a distance between

5,000 and 100,000 astronomical units (AUs) (1 AU = about 150 million kilometers or 93 million miles). The outer extent of the Oort cloud is

considered to be the "edge" of our Solar System, where the sun's physical and gravitational influence ends.

The Oort cloud probably

contains 0.1 to 2 trillion icy bodies in solar orbit. Occasionally, giant molecular clouds, stars passing nearby, or tidal interactions with the

Milky Way's disc disturb the orbit of one of these bodies in the outer region of the Oort cloud, causing the object to streak into the inner Solar

System as a so-called long-period comet. Such comets have very large, eccentric orbits and are observed in the inner Solar System only

once.

The objects in the Oort cloud and in the Kuiper belt are presumed to be remnants from the formation of the Solar System

about 4.6 billion years ago.

Stanley Miller and Harold Urey conducted the origin of life experiment to mimic the atmospheric conditions on Earth that might have been

responsible for forming the components of life. A flask was filled with methane, hydrogen, and ammonia and sealed. It was heated and

subjected to electrical sparks. A week later Miller and Urey observed that simple organic molecules had formed, including 13 amino acids that

are used to make proteins in living cells. The experiment confirmed that in a hypothetical environment some of the building blocks of life

could be created without having life to synthesize it.In 1954, radio galaxies were discovered; these bodies are millions of light years away pouring energy into the radio spectrum. The discovery

indicated that galaxies have been very active since they evolved billion of years ago, a finding consistent with the Big Bang Theory.

Two scientists were experimenting with a radio for astronomical research in 1955. They discovered that Jupiter was a strong source of radio

waves. Older research indicated that Jupiter's radio emissions had been recorded in observations 5 years earlier but not recognized.

Sputnik 1 was the first artificial satellite to be put into Earth's orbit. It was launched into low Earth orbit by the USSR on 4 October 1957, and

was the first in a series of satellites collectively known as the Sputnik program. Apart from its value as a technological first, Sputnik also

helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-

signal distribution in the ionosphere. The satellite travelled at 18,000 mile per hour, taking 96.2 minutes to complete an orbit, and emitted

radio signals at 20.005 and 40.002 MHz, which were monitored by amateur radio operators throughout the world. The signals continued for

22 days until the transmitter batteries ran out on 26 October 1957. Sputnik 1 burned up on 4 January 1958, upon reentering Earth's

atmosphere, spending 3 months in orbit.

On October 4, 1959, the Soviet space probe Luna 3 was sent to orbit near the Earth-moon system. The probe made its closest flyby at

6,200 kilometers from the moon near its south pole. The camera took 29 pictures over 40 minutes on October 7, 1959, from 03:30 UT to

04:10 UT at distances ranging from 63,500 to 66,700 kilometers above the surface, covering 70 percent of the lunar far side. Seventeen poor

quality but viewable photographs were transmitted to Earth before contact was lost with the probe on October 22, 1959. These were

mankind's first views of the moon's far side.

Infrared telescopes detect objects outside the Earth's atmosphere such as nebulae, young stars, and the gas and dust in other galaxies. All

objects with a temperature above absolute zero emit infrared radiation. Scientists used balloons to lift infrared telescopes to higher altitudes

about 25 miles up; in 1967 they were placed on rockets, and more recently they've been carried up on 747 jets. Placing infrared telescopes in

space completely eliminates interference from Earth's atmosphere.

Throughout the 1960s and 70s astronomers were developing sophisticated but low-cost balloon- and rocket-borne experiments to see what

our universe looked like from space. In 1970 Riccardo Giacconi, an Italian-American physicist, along with his colleagues launched the first x-

ray satellite, Uhuru. Uhuru identified the first potential black holes and a neutron star. Other x-ray satellite missions were launched in the

1970s: Ultraviolet Explorer (1978) and the Einstein Observatory (1979). Einstein was the first x-ray observatory that could take x-ray images

of objects outside our Solar System, revealing details about galaxy clusters and supernova remnants.

Giacconi received the 2002

Nobel Prize for his pioneering contributions to astrophysics, which led to the discovery of the cosmic X-ray sources.

Frank Low (1933-2009), an American physicist, was a pioneer in the field of infrared astronomy. The universe emits a huge amount of

infrared radiation, only a fraction of which reaches the Earth's surface. Infrared radiation is invisible and is mostly absorbed into the Earth's

atmosphere. Therefore, infrared research is best performed above the Earth's atmosphere using infrared telescopes that can be carried on

aircraft or satellites that orbit the Earth. Low invented the advanced thermal detector, the germanium bolometer, with a special cooling

system to extend the range of observable radiation to much longer wavelengths and thus detecting more information about the objects in our

universe.

Riccardo Giacconi (1931), an Italian/American astrophysicist, was the pioneer of x-ray astronomy. He led a small group of scientists to White

Sands, New Mexico, to launch a small U.S. Air Force sounding rocket into space. He equipped the rocket with a small instrument for detecting

x-rays, the first time a telescope would operate in flight. On its short flight it sensed x-rays coming from all directions. This was the first time

scientists detected x-rays from beyond our Solar System. This experiment opened the door to the field of x-ray astronomy. Giacconi received

the 2002 Nobel Prize for his work.


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On August 27, 1962, the American space probe Mariner 2 launched and headed for the planet Venus. One hundred nine days after launch,

Mariner 2 passed within 35,000 kilometers of Venus and became the first space probe to conduct a successful planetary encounter. Mariner 2

scanned the planet with infrared and microwave radiometers to collect data on the planet's atmosphere, magnetic field, charged-particle

environment, and mass. It also made measurements of the interplanetary medium during its flyby of Venus. Mariner 2's signal was tracked

until January 3, 1963, and it is thought to be still orbiting the sun.

In the late 1950s and early 1960s radio telescopes were detecting that certain celestial objects were emitting radio waves. At the time, no

one knew what these objects could be; they were star-like in size but had a strange ultraviolet spectra. In 1962 Maartin Schmidt studied the

spectrum of one of the objects (now Quasar 3C 273) and noted that it had been shifted a great deal. Astronomers realized that the unusual

spectra lines had been Doppler-shifted, corresponding to their high velocities as they traveled away from the sun.

These objects

were masquerading as stars with strong radio sources, and astronomers referred to them as "quasi-stellar radio sources," which was

shortened to "quasars."

Schmidt and Donald Lynden-Bell were awarded the Kavli Prize for their seminal contributions to

understanding the nature of quasars.

Arno Penzias and Robert Wilson were using a radio telescope when they discovered cosmic microwave background radiation left over from the

formation of the universe in the Big Bang. This discovery validated part of the Big Bang model and is important in our understanding of thecosmos.

Penzias and Wilson were awarded the 1978 Nobel Prize for their discovery.

Lyman Spitzer, Jr. (1914-1997), an American physicist, led the efforts for the Large Space Telescope, but not all scientists supported the

idea. They were concerned it would come at a cost to support for ground-based astronomy. In 1968, Spitzer's dream of a large telescope in

space began to come true when the Orbiting Astronomical Observatory was launched.

This lunar soft-lander gathered data about the lunar surface for the future manned Apollo Moon landings that began in 1969. The successful

soft landing of Surveyor 1 was the first one by an American space probe onto any extraterrestrial body, and it occurred just four months after

the first Moon landing by the Soviet Union's Luna 9 probe. This was also a success on NASA's first attempt at a soft landing on any

astronomical object.

The Orbiting Astronomical Observatory (OAO) Program was a series of four satellites, of which two missions were successful and two were

failures. The program was important for the future of orbiting telescopes and ultimately led to the development of the Hubble Space

Telescope and other orbiting observatories.

OAO-1 was launched April 8, 1966, but was terminated three days later after it

experienced a power failure.

OAO-2 was launched on December 7, 1968, and operated successfully until January 1973. The satellite

studied high-energy environments such as nova, supernovae, and comets, contributing to the development of ultraviolet

astronomy.

OAO-B was launched on November 3, 1970, carrying an ultraviolet telescope, but the satellite failed to separate fromthe launch rocket and eventually tumbled back into the atmosphere and burned up.

OAO-3, Copernicus, was launched August 21,

1972, and operated successfully until February, 1981. Copernicus carried a UV telescope and an x-ray experiment. It returned high-resolution

spectra of hundreds of stars and numerous x-ray observations, in addition to discovering several pulsars.

The field of interstellar chemistry had its beginnings in 1968 with the microwave detection of the first interstellar polyatomic molecule,

ammonia. Since then over 50 species have been identified in space. Before this it had been thought that molecular processes (as opposed, for

example, to atomic and nuclear processes) played little or no role in astrophysics. Conditions in interstellar space are wildly different than

here on Earth with extremely low pressure and temperatures. William Klemperer (1927), an American chemist, is a pioneer in the field -

leading research on how molecules work in the interstellar environment in order to better understand our cosmos.

Pulsars are rotating neutron stars that give the appearance of pulsing because they're rotating. Jocelyn Bell and Antony Hewish were studying

distant galaxies when they discovered pulsars as radio sources blinking on and off at a constant frequency. They were briefly thought to be

radiating from an extra-terrestrial civilization. Once their origin was understood they were called "pulsars" because their emission pulsed.

Pulsars have since been observed using optical, x-ray, and gamma-ray telescopes.

Hewish and Sir Martin Ryle were awarded the

first Nobel Prize for astrophysical research in 1974 for their pioneering research in radio astrophysics.

Apollo 11: Neil Armstrong and Edwin "Buzz" Aldrin, Jr. were the first humans to land on Earth's Moon. This was a major accomplishment inthe history of space exploration - July 1969

Apollo 12: The primary objective was improved landing precision and visiting the

Surveyor 3 probe - November 1969

Apollo 13: The Service Module oxygen tank exploded forcing the crew to abort the lunar

landing. They moved into the Lunar Module with limited resources to escape decreasing air pressure until they guided the crippled craft back

to Earth four days later - April 1970

Apollo 14: The mission successfully landed at the site intended for Apollo 13. On two moon

walks the crew captured the first color images of the Moon's surface and conducted the first materials science experiments in space - January

1971

Apollo 15: The first mission designed to explore the Moon over longer periods, greater ranges and with more instruments for

collecting scientific data including the first use of a Lunar Rover - July 1971

Apollo 16: The first mission to land in lunar highlands -

April 1972

Apollo 17: This was the last Apollo lunar mission but still retains the titles for most recent manned Moon landing and

Astronomers wanted bigger and better telescopes to study the universe, but they were limited by the size of the mirror in telescopes because

the mirrors were likely to warp under their own weight and distort the images produced. The single mirror was replaced by multiple smaller

mirrors that would operate together by computer control. One telescope had as many as 36 individual mirrors. Meanwhile, technology for

making larger single mirrors continued to improve, and scientists created single mirrors more than 8 meters in diameter. Earth's atmosphere

was still causing images to blur. Scientists turned to adaptive optics, a method developed by the military, to compensate for the uneven

lighting in the atmosphere. Today, these giant mirrors use adaptive optics to create sharper images.

On August 17, 1970, Venera 7 was launched to study the Venusian atmosphere and other phenomena of the planet. Venera 7 entered the

atmosphere of Venus on December 15, 1970, and a landing capsule was jettisoned. After aerodynamic braking, a parachute system was

deployed. The capsule antenna was extended, and signals were returned for 35 minutes. Weak signals were received for another 23 minutes

after the spacecraft landed on Venus. Venera 7 was the first spacecraft to transmit data from the surface of another planet.

Mariner 9 launched on May 30, 1971, headed toward Mars, which it reached on November 13, 1971, becoming the first spacecraft to orbit

another planet. The objective of Mariner 9 was to study Mars' changing atmosphere and surface over time. Mariner 9 also took on the

additional mission objectives of Mariner 8, namely to map 70 percent of the Martian surface, because of the failure of the Russian Cosmos 419

to launch. After months of dust storms the orbiter was finally able to capture clear images and map 85 percent of the Martian surface; more

than 7,000 images were transmitted back to Earth.

The Mariner 9 mission resulted in a global mapping of the surface of Mars,

including the first detailed views of the Martian volcanoes, Valles Marineris, the polar caps, and the satellites Phobos and Deimos. It also

provided information on global dust storms, the triaxial figure of Mars, and the rugged gravity field, as well as evidence of surface aeolian

activity.

Pioneer 10 launched on March 2, 1972, and was the first spacecraft to travel through the asteroid belt and the first spacecraft to make directobservations and obtain close-up images of Jupiter. Pioneer 10 passed within 81,000 miles of Jupiter, marking humans' first approach to

Jupiter and opening the way for exploration of the outer Solar System. During its Jupiter encounter, Pioneer 10 imaged the planet and its

moons and took measurements of Jupiter's magnetosphere, radiation belts, magnetic field, atmosphere, and interior. These measurements of

the intense radiation environment near Jupiter were crucial in designing the Voyager and Galileo spacecraft. Pioneer 10's signal was lost in

2003, but it continues to coast through interstellar space heading toward Aldebaran, the brightest star in Taurus; it will take Pioneer more

than 2 million years to reach it.

8/3/2019 Time

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