Notes: Sun-Earth-Moon System

A. The Earth1. ____Axis__ - imaginary vertical line around which Earth spins2. _Rotation___– the spinning of Earth around its axis that causes day and night3. _Revolution__– Earth’s yearly orbit around the Sun

a. Earth’s orbit is an __ellipse___, or elongated, closed curve b. Because the Sun is not centered in the ellipse, the distance between Earth and the Sun

changes during the year (video clip: Planetary Rotation and Revolution)

4. Earth’s __tilt____ causes seasons a. The hemisphere tilted toward the Sun receives more daylight hours and radiation than the

hemisphere tilted away from the Sun

b. The longer period of sunlight is one reason summer is warmer than winter

Let’s Illustrate: Reason for the Seasons (video clip Earth’s Tilt on It’s Axis)

B. The Moon1. Motions of the Moon

a. ___Rotation___ on its axis which takes about _29.5_ days, with the same side always facing Earth. (video clip: movement of the moon)

b. Shines because it reflects sunlight (video clip: Why we always see the same side of the moon)

2. Phases of the Moon a. _New Moon____– the moon is between Earth and the

Sun and cannot be seen b. __Waxing______– more and more of the lighted side of the moon can be seen each night (waxing crescent,

first quarter, waxing gibbous) c. __Full Moon____– all of the moon’s lighted side is

visible d. __Waning____– less and less of the lighted side of the

moon can be seen each night (waning gibbous, third quarter, waning crescent) (video clip: phases of the moon)

3. Eclipses – when the Earth or the Moon casts a shadow on the other a. Solar Eclipse - the moon moves directly between Earth and the Sun, shadowing part of Earth; occurs during the day ; during a new moon (video clip: solar eclipse)

(video clip: Sun’s corona during a solar eclipse)

b. Lunar Eclipse - the Earth’s shadow falls on the moon; occurs at night ;during a full moon (video clip: lunar eclipse)

4. Tides - at any shoreline on Earth, the height of the water will rise and fall throughout the day. Gravity is responsible for these regular increases and decreases.

a. The moon’s gravity pulls on Earth. 1.) This pull creates a bulge of water on the side of Earth facing the Moon. 2.) Earth’s rotation and inertia creates a bulge on the opposite side of Earth as well 3.) The two bulges create high tides and

between the two bulges are low tides. (video clip: tides)

b. The sun’s force on the tides is less than half of the effect of the Moon.

1.) It creates two additional bulges a.) Spring Tide - the sun, moon, and earth align during a new and full

moon and high-tide waters are higher than normal

b.) Neap Tide - when the moon is in the first or third quarter and high

tides are lower than normal and low tides are higher than normal

C. The Sun 1. Solstice - the day when the Sun reaches its

greatest distance north or south of the equator a. Summer Solstice - occurs June 21 or 22 in

the northern hemisphere b. Winter Solstice - occurs December 21 or 22 in the northern hemisphere

2. Equinox - the day when the Sun is directly over Earth’s equator

a. Daylight and nighttime hours are equal all over the world

b. Spring Equinox occurs on March 20 or 21 in the northern hemisphere

c. Fall Equinox occurs on September 22 or 23 in the northern hemisphere

Life Cycle of Stars

• 1. Nebula – how a star begins as a large cloud of gas and dust; gravitational force causes the nebula to contract; it breaks into smaller pieces when gas and dust become so hot that nuclear fusion starts; A STAR IS BORN. Stars spend many years in a relatively constant state. The center shrinks, and the outer part of the star expands.

Life of an Average Star

• 2. All average stars, including our Sun, eventually becomes a Red Giant.

• 3. Planetary Nebula – the outer part of the red giant grows larger until it eventually drifts into outer space.

• 4. The hot outer core left behind is a White Dwarf. A white dwarf is about 1 million times as dense as the Sun. Most of its fuel is gone, so it not longer produces energy. It gives off enough leftover heat to glow faintly for perhaps a billion years. It continues to cool until it becomes cold and dark. It is then called a Black Dwarf.

Life of a Massive Star

• 2. If the star is a massive star, it becomes a Supergiant.• 3. The core eventually collapses violently, sending a shock

wave outward through the star. The outer portion explodes producing a Supernova. This can be million of times brighter than the original star.

• 4. Material left from a supernova is called a Neutron Star. These are about twice as massive as the Sun and very dense.

• 5. If material left over from the supernova is more than three times as massive as the Sun, it becomes a Black Hole because the core collapses. The gravity from this mass is so strong that nothing can escape from it, not even light.

• Stars take different lengths of time to go through their life cycle. The length of a star’s life depends on its mass. The most massive stars live the shortest lives because they use up their fuel more quickly than stars with less mass. The life cycle of a star is often compared with that of the Sun, which is an average star. In about 5 billion years, the Sun will become a giant. Now it is a main sequence star, between an average star and a red giant. The Sun has an expected lifetime of about 10 billion years.

How are Stars Classified?• All stars are huge spheres of glowing gas. Made up

mostly of hydrogen, stars produce energy through nuclear fusion.

• Stars are classified according to color, temperature, size, composition, and brightness.

• The brightness of a star is described in two ways:1. apparent magnitude – is a star’s brightness as seen from Earth2. absolute magnitude – is the brightness the star would have if it were a standard distance from Earth; actual brightness

H-R Diagram• About 100 years ago, two scientists Ejnar Hertzsprung and Henry

Norris Russell made a graph to find out if the temperature and brightness of stars are related. They plotted the surface temperatures of stars on the x-axis and their absolute brightness on the y-axis. The points formed a pattern. This graph is still used today, called the Hertzsprung-Russell diagram.

Main Sequence- diagonal band on H-R diagram (about 90% of stars)* Upper Left – hot, blue, bright stars* Lower Right – cool, red, dim stars* Middle – average yellow stars like the Sun

The other 10% are dwarfs, giants and super giants.

The Solar System• The Solar System is made up of 8 planets, the Sun,

many small objects, and a huge volume of space.• The sun is the center of our Solar system.• All objects in the solar system revolve around the

sun.

The Planets

• Inner Planets– Small and rocky with iron cores.– Includes: Mercury, Venus,

Earth, Mars

• Outer Planets– Large and lightweight– Made up of liquid and gases

– Includes: Jupiter, Saturn, Uranus and Neptune

Inner PlanetsMercury

• Closest to the Sun; 36 million miles from the Sun• Smallest planet; 3,000 miles in diameter• Orbit – 88 days Rotation – 59 days• No Moons• Thin atmosphere is constantly replenished by the solar

wind• Surface is rocky and cratered

Venus• Second from the sun; 67 million miles from the Sun• Similar to Earth in size and mass; 7,500 miles in diameter• Orbit – 225 days Rotation – 243 days• No Moons• Brightest planet• Extremely dense atmosphere of clouds• Surface temperature of 450⁰C• Rocky surface with volcanic cracks

Earth• Third planet from the Sun• More than 70% of the surface is covered in water• Atmosphere protects surface from most meteors and Sun’s

radiation• One large Moon• Only planet where life is known to exist

Mars• Fourth planet from the Sun; 141.5 million miles from the

Sun• Called the Red Planet• 4,215 miles in diameter• Orbit – 2 years Rotation – 24 ½ hours• 2 Moons: Phobos and Deimos• Has dust storms that cover the planet for days• Rocky surface covered with sand• Has largest volcano in the solar system• Thin atmosphere of mostly carbon dioxide• Tilted on its axis; which causes seasons

Outer Planets Jupiter

• 5th from the Sun; 483.3 million miles form Sun• Largest planet; 88,700 miles in diameter• Orbit – 12 years Rotation – 10 hours• 63 Moons• Thick gas atmosphere of mostly hydrogen and

helium• Storms swirl the planet; the largest being the Great

Red Spot

Saturn• 6th planet; 886 million miles form the Sun• Second largest planet; 75,000 miles in diameter• Orbit – 29 ½ years Rotation – 10 hours• Has beautiful rings around it (thousands of them)• 30 Moons; the largest Titan is larger than Mercury• Thick gas atmosphere (hydrogen and helium)

Uranus• First seen in 1781• 7th from the Sun; 1,778 million miles from Sun• 30,900 miles in diameter• Orbit – 84 years Rotation – 11 hours• 21 Moons• Ocean of water and ammonia• Large and gaseous• Thin rings

Neptune• 8th planet: 2,793 million miles from Sun• 32,900 miles in diameter• Orbit – 165 years Rotation – 16 hours• Blue-green planet• 2 main rings, 3 small rings• 8 moons • Poisonous thick gas atmosphere

Pluto• Last planet to be discovered (1930)• 3,660 million miles form the Sun• 2,000 miles in diameter• Orbit – 248 years Rotation – 6 days• 1 moon, Charon, half the size of the planet• Small, rocky, made of methane ice• In 2006 Pluto was demoted from being a planet and is now classified

as a dwarf planet

Quiz• How many planets do we have in our solar system?• What galaxy are we in ?• List the planets, starting with the inner planets.• Give characteristics of the inner planets and the

outer planets

Notes: Sun-Earth-Moon System

A. The Earth1. __________– imaginary vertical line around which Earth spins2. _________– the spinning of Earth around its axis that causes day and night3. _________– Earth’s yearly orbit around the Sun

a. Earth’s orbit is an __________, or elongated, closed curve b. Because the Sun is not centered in the ellipse, the distance between Earth and the Sun

changes during the year4. Earth’s _________ causes seasons

a. The hemisphere tilted toward the Sun receives more daylight hours and radiation than the

hemisphere tilted away from the Sun

b. The longer period of sunlight is one reason summer is warmer than winter

Let’s Illustrate: Reason for the Seasons

B. The Moon1. Motions of the Moon

a. ____________on its axis which takes about _____ days, with the same side always facing Earth.

b. Shines because it reflects sunlight2. Phases of the Moon

a. _____________– the moon is between Earth and the Sun and cannot be seen

b. _____________– more and more of the lighted side of the moon can be seen each night (waxing crescent,

first quarter, waxing gibbous) c. ____________– all of the moon’s lighted side is visible d. ____________– less and less of the lighted side of the

moon can be seen each night (waning gibbous, third quarter, waning crescent)

3. _______________– when the Earth or the Moon casts a shadow on the other a. _____________- the moon moves directly between Earth and the Sun, shadowing part of Earth; occurs during the _____; during a ___________

b. _____________ - the Earth’s shadow falls on the moon; occurs at ________; during a _________

4. ________– at any shoreline on Earth, the height of the water will rise and fall throughout the day. __________ is responsible for these

regular increases and decreases. a. The moon’s gravity pulls on Earth. 1.) This pull creates a bulge of water on the side of Earth facing the Moon. 2.) Earth’s rotation and inertia creates a bulge on the opposite side of Earth as well 3.) The two bulges create high tides and

between the two bulges are low tides.

b. The sun’s force on the tides is less than half of the effect of the Moon.

1.) It creates two additional bulges a.) ______________– the sun, moon, and earth align during a new and full

moon and high-tide waters are higher than normal

b.) _____________– when the moon is in the first or third quarter and high tides are lower than normal and low tides are higher than normal

C. The Sun 1. _____________– the day when the Sun reaches its

greatest distance north or south of the equator a. ______________occurs June 21 or 22 in the northern hemisphere

b. ______________occurs December 21 or 22 in the northern hemisphere

2. ____________– the day when the Sun is directly over Earth’s equator a. Daylight and nighttime hours are equal

all over the world b. _______________occurs on March 20 or

21 in the northern hemisphere c. ________________ occurs on September 22

or 23 in the northern hemisphere