Name _____________________________________________________________

C2 Space Exploration Workbook

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Mercury Unveiled Emily Sohn From Science News for Kids Feb. 27, 2008 Astronomy isn't a popularity contest, but some planets seem to get all the attention. Jupiter is biggest. Saturn has many rings. Mars may harbor life. For years, Mercury has lurked in the shadows of its flashier neighbors. Now, the smallest planet finally is getting its time in the spotlight. Last month, scientists enjoyed their first good look at Mercury in more than 30 years. On January 14, NASA's MESSENGER spacecraft flew by the planet. Along the way, it collected a variety of data, including more than 1,200 high-quality images. What's more, the flyby revealed a large section of Mercury that had never been seen before at close range. In recent years, spacecraft have visited most of the Solar System. But Mercury, the planet closest to the Sun, remained largely unexplored.

MESSENGER took this image on January 14 of regions on Mercury that had never before been seen from a spacecraft. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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"There aren't very many new worlds to be found," says Clark Chapman. "Mercury really is that." He's a planetary scientist at the Southwest Research Institute in Boulder, Colo., and a member of the MESSENGER science team. As analyses get under way, surprises are already piling up. Observations include tons of craters, huge cliffs, evidence of volcanoes, and a strange, spider-shaped formation. And that's only the beginning. MESSENGER will fly by Mercury again in October and a third time in September 2009. In 2011, the spacecraft will enter a yearlong orbit of the planet. It will be the first spacecraft ever to orbit Mercury. As the mission progresses, scientists hope it will answer a long list of questions about the planet's surface, its atmosphere, and other details. "I would guess the data we got in this first flyby are equivalent to all the previous knowledge we've had of Mercury from all sources," Chapman says. "When this mission is done, we will really figure out how Mercury works," he adds. "And as we think about why it is different from Earth, it will give us some insight into our planet and into how planets formed." Mission findings Much of what we know about Mercury comes from NASA's Mariner 10 mission, which flew by the planet three times in 1974 and 1975. Although its glimpses of Mercury were brief, Mariner 10 helped confirm some basic discoveries about the planet—such as that it has a very thin atmosphere, a magnetic field, and a large iron core. In photos taken by Mariner 10, Mercury resembled the Moon, which has lots of craters and a mostly unchanging surface. The two objects are also nearly the same size. But Mariner 10's instruments were less advanced than MESSENGER's are. And the earlier Mariner mission saw just one side of Mercury in daylight—leaving about 55 percent of the planet unseen. During its recent flyby, MESSENGER was able to observe about half of the remaining area. (The spacecraft will see the rest of the planet in October.) The new images show that Mercury is different from the other rocky objects in our inner Solar System—Venus, Earth, Mars, and the Moon.

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"It was not the planet we expected," says Sean Solomon, a planetary scientist at the Carnegie Institution of Washington (D.C.) and principal investigator of the MESSENGER team. "It was not [like] the Moon. It's a very dynamic planet with an awful lot going on." One of MESSENGER's most interesting discoveries so far is a strange formation called the Spider. Unlike a real spider, which has only eight legs, this one has more than 50 leglike trenches that stretch out in all directions from a large, relatively dark central area that surrounds a crater that is 40 kilometers (25 miles) wide. The entire structure lies within another huge crater called the Caloris basin.

Mercury's Spider is unlike anything seen elsewhere in the Solar System. NASA/JHU APL/Carnegie Institution

"The Spider feature is unlike anything we've seen anywhere in the Solar System," Solomon says. There may, however, be similar features on Venus, Chapman notes. How did the Spider form? "We have theories," says Louise Prockter, a MESSENGER team member from the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "But the real answer? It's anyone's guess," she says. Besides the Spider, MESSENGER's first pass of Mercury revealed a surprisingly large number of craters. These bowl-shaped depressions form when objects from outer space strike a planet or Moon, or when material ejected by these impacts strikes outside the initial crater. Craters can also develop when volcanoes erupt.

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On January 14, the MESSENGER spacecraft's narrow angle camera revealed hundreds and hundreds of craters on Mercury's surface. The crater in the lower left corner of this image measures about 230 km (143 miles) across. The crater nestled inside it is about 85 km (53 miles) across. NASA/JHU APL/Carnegie Institution

In just one section of one of MESSENGER's images, Chapman counted more than 700 small craters. Each measured between a quarter-mile and several miles across. By counting craters, measuring them, and analyzing their locations, he hopes to figure out when these features formed. Studying craters can also show if and when molten material emerged from deep within the planet's interior. MESSENGER has already revealed that there is a surprising amount of this volcanic activity. Further observations will reveal more about what's happening inside the planet. At long last Scientists have had to wait a long time to get a good look at Mercury, mostly because the planet is tough to reach. Heat is one reason: Temperatures on the planet can hit 800 degrees Fahrenheit (roughly 425 degrees Celsius). It's taken decades of engineering research to develop solar panels, cameras, and other equipment that can perform under such extreme conditions. Getting into orbit around Mercury also requires some feats of physics. The Sun's gravity accelerates any spacecraft that ventures near the star. MESSENGER will therefore have to fight the Sun's gravity in order to slow enough for Mercury's gravitational field to capture and hold the spacecraft in the planet's orbit.

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Braking the spacecraft's speed by firing up its rockets would use lots of fuel (which would have been too heavy for MESSENGER to carry). So instead, the spacecraft will rely on the tugs of gravity from Earth, Venus, Mercury, and the Sun to weave around the planets until it reaches the correct position and speed. The strategy is clever, but it takes a while. In 2011—nearly 7 years after it left Earth—MESSENGER will finally enter Mercury's orbit.

MESSENGER took off from Launch Pad 17-B, at Cape Canaveral Air Force Station in Florida, on August 3, 2004 at 2:15:56 a.m. Eastern Daylight Time. NASA

The wait should be worth it, according to the MESSENGER researchers. Spacecraft that orbit planets provide a lot more information than do spacecraft that simply fly by planets. And as the mission continues, scientists hope to solve some of Mercury's mysteries. Why, for example, is Mercury the only planet in the inner Solar System—other than Earth—that has a magnetic field? And is it true, as some planetary scientists theorize, that Mercury formed in the asteroid belt between Mars and Jupiter before moving to its present location?

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Mercury's climate has also raised a number of questions. The planet is an extremely hot place, but it has wild temperature swings, with an 1100ºF (about 600ºC) difference between day and night in some places. Its poles always remain a frigid –300ºF (about –180ºC). In the shadows of craters in the polar regions, scientists have even observed what appears to be water ice. "If Mercury can have ice," Chapman asks, "Why doesn't the Moon? And where does the water come from?" The questions go on and on. After decades of planning, watching, and nervous waiting, MESSENGER scientists are excited to see what the mission reveals next. "I want to emphasize that the best is yet to come," says Robert Strom, a planetary scientist at the University of Arizona, Tucson, and member of the MESSENGER research team. "What we're seeing here is just the tip of the iceberg," he adds. "Wait until we go into orbit and make two more flybys . . . This is a whole new planet we're looking at." Update MESSENGER entered orbit around Mercury March 17, 2011 and is now operating in Mercury’s orbit. One of the first pictures taken from Mercury’s orbit.

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Questions 1. Observations of Mercury include… a. b. c. d. 2. _________________________ flew by Mercury in _________ and _________. 3. The surface of Mercury resembles our _________________. 4. Explain how scientists think the spider feature on Mercury formed. __________________________________________________________________ __________________________________________________________________ 5. In one area, there were over _____________ craters in the picture. 6. Explain why Mercury is hard to reach. __________________________________________________________________ __________________________________________________________________ 7. What is the current status of MESSENGER? __________________________________________________________________ __________________________________________________________________

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NEAR Shoemaker Mission to Eros (Adapted from the NEAR Press Kit)

Introduction The encounter of the Near Earth Asteroid Rendezvous (NEAR) spacecraft with asteroid 433 Eros began on Feb. 14, 2000. Asteroids, comets, and meteorites have stirred human imaginations for hundreds of years, inspiring great speculation as well as scientific observations. NEAR’s yearlong study of Eros began to unravel many mysteries that surround these near-Earth asteroids. Asteroid 433 Eros The target of the NEAR mission is 433 Eros, the first-discovered near-Earth asteroid (NEA) and the second-largest. Eros is shaped like a potato. Eros was discovered on Aug. 13, 1898, by Gustav Witt. In a break with tradition at the time, the asteroid was given a male name: Eros, the Greek god of love and son of Mercury and Venus. Eros has an orbit that crosses Mars' path but does not cross Earth’s orbit. It takes 1.76 years to travel around the Sun. The closest approach of Eros to Earth in the 20th century was on January 23, 1975. It came within 14 million miles of Earth. Eros has helped us to learn more about the mass of the Earth-Moon system. Daytime temperature is about 100o C (212o F), while at night it plunges to -150o C (-238o F). Gravity on Eros is very weak but sufficient to hold a spacecraft in orbit. A 100-pound (45-kilogram) object on Earth would weigh about an ounce on Eros, and a rock thrown from the asteroid's surface at 22 miles/hour (10 meters/sec) would escape into space.

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Eros Facts ---------- Size: 33 km x 13 km x 13 km Rotation Period: 5.270 hrs Orbital Period: 1.76 Early Mission Results

During its year-long orbit, NEAR Shoemaker flew past Eros at altitudes from 3 to 35 miles (5 to 56 km), producing thousands of spectacular images and returning data that will be analyzed for years to come. Combining digital images and data from the laser rangefinder, scientists have

built the first detailed map and three-dimensional model of an asteroid. Previously scientists believed that asteroids were either solid iron or cosmic

rubble piles; Eros is neither. Data suggests that Eros is a cracked but solid rock, possibly a “chip” off a larger body, made of some of the most primitive materials in the Solar System.

The loose rock on the surface of Eros is nearly 300 feet (91 meters) deep in places. Data indicate the loose rock has moved downhill, smoothing over rough areas and spilling into craters.

The cratering on Eros has surprised scientists, with fascinating square ones and many fewer small craters than expected. More than 100,000 craters wider than 50 feet (15 meters) have been counted. Also, the large number of boulders was unexpected, with about one million house-sized or larger boulders.

The last images returned showed clusters of boulders, a mysterious area where the surface appears to have collapsed, and extremely flat, sharply delineated areas in the bottoms of some craters, indicating the story of Eros's composition is still emerging.

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Landing On Eros

After a journey of more than two billion miles, NEAR Shoemaker gently landed on the tips of two solar panels and its bottom edge on February 12, 2001. The spacecraft snapped 69 detailed pictures during the final three miles (five km) of its descent, the highest resolution images ever obtained of an asteroid, showing features as small as one centimeter across. The slow touchdown speed left the spacecraft intact and still sending a signal back to Earth. NASA decided to extend the mission to February 28th, to get "bonus science" from the spacecraft, which had already collected 10 times more data than originally planned. This allowed the gamma-ray spectrometer to collect data from an ideal vantage point about four inches (10 cm) from the surface, in the first gamma-ray experiment that has ever been done on the surface of a body other than Earth. The NEAR mission returned more 160,000 detailed images that solved some mysteries and unveiled new ones. The amazing amount of data collected will be shared with scientists all over the world, to reveal facts about Eros and our Solar System that no one knows today.

Your assignment is to write a one page report explaining how NEAR Shoemaker helped us to learn more about asteroids. Include some results. 2nd Report Select and answer one of the following after your one page report. (Your response must be complete, neatly written, and fully cover the topic. A sentence or two will not adequately answer the question): Explain why astronomers are concerned about asteroids that come near Earth. What do you think it would be like to walk on an asteroid?

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Eros Report __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________

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Second Report __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________

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The work of astronomers Copernicus, Brahe, and Kepler was remarkable. All their observations of the night sky were made by using their own eyes. The invention of the telescope allowed scientists to “extend their senses” for the first time. It is considered one of the most important instruments in the Scientific Revolution of the 17th century. Who Invented the Telescope? No one knows who invented the telescope. A story is told that two little children playing with lenses in the shop of Hans Lippershey, a Dutch reading-glasses maker. When the children looked at a nearby weather vane through two lenses held together, it became larger and clearer. Lippershey put a tube in between the two lenses. This may have been one of the first telescopes. This early model only magnified an image by three or four

times. This means that a marble seen through this device would appear three or four times larger than its actual size—maybe the size of a ping-pong ball. Lippershey was the first person to try to sell his telescope. In 1608, he applied for a patent on a device with multiple lenses. This would protect his idea from being stolen by someone else. He was required to make three identical telescopes and to keep his method a secret. Making more was not a problem. He had trouble keeping his secret. Later, Jacob Metius applied for a patent on a

device for "seeing faraway things as though nearby." His device was a tube with one convex lens (curved outward) and one concave lens that curved inward.

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There are two different stories about what the patent board decided. One version is that they turned down Metius’ application. He became so upset that he refused to show his telescope to anyone. Even the tools he used to make it were destroyed after he died. The other says that government officials discussed the patent applications of both Lippershey and Metius. They thought that the device was too easy to copy to patent. They gave Metius a small amount of money and paid Lippershey to make several telescopes. These looked more like “spyglasses” than our modern telescopes. Because they used lenses that refracted (or bent) light, they were called refractor telescopes. Galileo Received Credit for the Refractor Telescope In 1609, Galileo Galilei heard that Lippershey was on his way to Venice to sell his telescope. Galileo needed money. The Venetians were offering Lippershey a good price for his telescope. In 24 hours, Galileo made a telescope. He sent word of “his invention” to the government. Galileo’s salary rose 520 to 1000 florins per year. Whatever the truth of these stories, three things are certain. The first telescopes were not invented by scientists; they were invented by craftsman. Next, Galileo did not invent the telescope. Finally, telescopes changed astronomical observation. Scientists depended upon larger and better telescopes to advance their study of the universe. Galileo used a telescope with lenses that magnified objects about 20 times their size. With this telescope, he discovered the moons of Jupiter, the rings of Saturn, the changing apparent shape of Venus, sunspots, and solar rotation in less than ten years. During the same decade, at least ten other astronomers built their own telescopes using different combinations and types of lenses. Many of these were used to verify, support, and extend Galileo’s discoveries. Early Refractor Telescopes Reached Their Limits There were several problems with Galileo’s telescopes. They only allowed for a narrow field of view (what could be seen). The images produced through the lenses were blurry.

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Around 1630, a German astronomer, Johannes Kepler, proposed some solutions. To expand the area that could be visible through a telescope, Kepler suggested the concave eyepiece be replaced by a convex one. This design produced an upside-down image. It was corrected by the two-convex lens design. He discovered that by flattening the shape of the lens, the image quality could be improved. This solution caused a problem. With a flatter lens, the only way to increase the magnification power of the telescopes was to increase the length of these telescopes. By the middle of the 17th century, the length of telescopes became longer and longer. They were eventually were too large to control. Isaac Newton Built a Reflector Telescope Another problem was that the glass lenses caused light to separate into colors. You may have observed how a glass prism creates a rainbow effect. The early telescope lenses produced a ring of color around bright objects. This is called chromatic aberration. An English scientist, Sir Isaac Newton, solved this problem by using metal

mirrors instead of glass lenses. This designed solved the “color” problem. Better yet, it was six inches long. It could magnify objects 40 times. Some of the best reflector telescopes were designed and built by William Herschel. He built a telescope that was used by Johann Schröter, the president of the “Celestial Police.” This group was formed to search for and discovering the “missing planet.” Astronomers believed it would be found between the orbits of Mars and Jupiter. Images continued to be blurry with the early reflector telescopes. Technology finally made it possible to grind the lenses and mirrors into different shapes. Newton’s design led to a new problem. The metal mirror became dull easily. It required frequent polishing. Even so, the introduction of the reflecting telescope inspired a new surge of astronomical discoveries. Scientific pursuits continued to inspire improvements to the telescope.

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Questions relating to “Seeing Faraway Things As Though Nearby” 1. Prior to the invention of the telescope, how did early scientists (e.g., Copernicus, Brahe, and Kepler) make observations of celestial bodies? __________________________________________________________________ __________________________________________________________________ 2. In technology development, many people are usually involved over a period of time. Often, however, one person gets credit.

a) What are some of the conflicting stories regarding the individuals who were involved in the invention of the first telescopes? Provide details: Who? What? and Where?

__________________________________________________________ __________________________________________________________

b) When was the telescope invented?

__________________________________________________________ c) Who received credit for the invention? __________________________________________________________

3. How did science advance because of the invention of the telescope?

a) What were some of the discoveries made using early telescopes? _______________________________________________________________

_______________________________________________________________

b) Who was responsible for these discoveries? _______________________________________________________________

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4. Science and technology depend on each other to progress. The need for better science drives improvements in technology, and vice versa, technological improvements make scientific advances possible.

a) What were some of the improvements that were made to the early refractor telescopes?

_______________________________________________________________

_______________________________________________________________

b) What is the difference between the refractor and the reflector? _______________________________________________________________

_______________________________________________________________

c) Why was the reflector telescope built? How was it an improvement over the refractor telescope?

_______________________________________________________________

_______________________________________________________________

d) Who was one of the first to build this type of telescope? When was it built? _______________________________________________________________

_______________________________________________________________ 5. How did the telescope, and the contributions of those who used the early telescopes, revolutionize astronomical observation? __________________________________________________________________ __________________________________________________________________

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Comparing Reflecting and Refracting Telescopes

Refracting Telescopes

The purpose of a refracting telescope is to collect and concentrate light from distant objects. All refracting telescopes are basically the same. It is made up of lenses. As light passes through the lens, it is refracted. (You should remember this term from the light unit!) The refractor has two lenses. The first is the primary lens. This is located in the front of the telescope. The light is refracted until it hits the second lens – the eyepiece lens. This is where you look to see the object at which your telescope is pointed.

The light waves travel parallel to each other until they hit the primary lens. The primary lens than refracts the light back to the eyepiece.

A problem with refractors is chromatic aberration. (If you look at an image through a refractor’s eyepiece and see a rainbow around the edges of an object, you are experiencing chromatic aberration.) Using the proper lenses will make sure the light waves refract to the same point.

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Reflector Telescopes

A reflector uses mirrors to produce and image in the eyepiece. Light waves travel into the telescope’s tube, reflect off the mirror, and hit a secondary mirror. It reflects into the eyepiece. Sir Isaac Newton made the first reflector. It is traditionally called the Newtonian Reflector. The primary mirror collects and concentrates light from distant objects. The parallel light waves reflect off the mirror to the secondary mirror. The secondary mirror reflects the light into the lens of the eyepiece. The light is refracted through the lens in the eyepiece where you look to see the image. Because the reflector uses mirrors, you don’t have a problem with chromatic aberration like you do with refractors. Images are sharp and clear. There are many different types of reflecting telescopes. The key difference between the different designs is the location of the secondary mirror.

Cassegrain Reflector Schmidt-Cassegrain Reflector With this information, complete the graphic organizer on the next page.

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What Can You See With a Telescope? The first four asteroids—Ceres, Pallas, Juno, and Vesta— were discovered between 1801 and 1807. No asteroids were found until 1845—almost forty years later—even though groups of amateur and professional astronomers designed special sky-mapping projects to search for them. A Lull in Asteroid Discovery Why were no new asteroids found during this period? Most were too small and dim to be easily observed through the early 19th-century telescopes. Even the largest telescopes were not big enough to find asteroids that were much smaller and/or dimmer than the first four asteroids that had already been found. Even when the four largest asteroids were seen through those telescopes, they appeared only as points of reflected Sunlight. They looked very much like the stars around them, except that they moved. Size a Factor in Asteroid Discovery

Ceres, the largest asteroid, is about 600 miles in diameter. Pallas is about 350 miles in diameter. Vesta is about 340 miles in diameter. Juno is the smallest. It is about 145 miles in diameter.

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William Herschel attempted to measure the size of Ceres and Pallas by looking at the asteroids through a telescope with one eye and comparing them to a small disk of a known size at a given distance. Herschel’s estimated diameters of 160 miles for Ceres and 140 miles for Pallas were smaller than their actual diameter. Most of the asteroids discovered between 1845 and 1890 ranged in size between 50 and 80 miles in diameter. Hygeia, found in 1849, is an exception, with a diameter of about 250 miles. It is dimmer than any of the first four discovered. Only about 30 asteroids with diameters greater than 120 miles have been found. It is estimated that there are 250 asteroids larger than 62 miles in diameter and perhaps 1,000,000 with diameters greater than one-half a mile. Asteroid Brightness—Another Factor to Consider The size of the majority of asteroids is quite small, but that is not the whole story. An asteroid’s brightness varies according to its orbital position and its distance from Earth. It also depends on what is on its surface. Another factor is the shape of the asteroid. An asteroid with an irregular shape will have a changing brightness that depends on which part of the surface or face of the object is facing Earth and is lit by the Sun. The table below shows the brightest magnitude for the first ten asteroids, The higher the magnitude, the dimmer the asteroid appears to an observer on Earth.

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Ceres is about twice the size of Vesta. Vesta, which is 219,480,000 miles from the Sun, orbits slightly closer to the

Earth than does Ceres, which is 257,610,000 miles from the Sun. Vesta reflects four times more light than Ceres’.

The Sun’s magnitude is -27, the Moon -12, Venus -4. The brightest stars are –1. An object of approximately the 6th magnitude, like 3 Juno, is barely visible to a person with good eyesight on a clear, Moonless night. With a good set of binoculars, one can see objects down to the 10th magnitude. With an 8-inch reflecting telescope, an observer can manage to see objects of 14th magnitude on very dark nights. The faintest objects detectable with the largest ground-based telescopes are about magnitude 30. Questions relating to “What Can You See with a Telescope?” 1. How long after Vesta was discovered in 1807 was the next asteroid found? What was its name? Why was there a lull in asteroid discoveries between 1807 and 1845? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. Compare the magnitude of Astraea and Ceres. Which of these asteroids is the brightest? __________________________________________________________________

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3. In the asteroid names, 1 Ceres and 5 Astraea, what do the numbers stand for? __________________________________________________________________ 4. Hershel attempted to measure the size of Ceres and Pallas. How accurate were his measurements? __________________________________________________________________ __________________________________________________________________ 5. One person tells you that it is a long way to the next large city. Another person says that it is 150 miles to the next large city. Which gives you the most precise information? Explain your answer. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________

New Eyes to Scan the Skies Stephen Ornes From Science News for Kids May 20, 2009 Four hundred years ago, an Italian scientist named Galileo Galilei became the first person to see the craters on the Moon. Galileo, who also observed four of Jupiter’s Moons and the rings of Saturn, was one of the first people to use a telescope to study the sky. Since then, telescopes have become the most important tool used by astronomers. All over the world — from the mountains of Hawaii to the icy plains of Antarctica — astronomers use telescopes to study the stars, galaxies and planets of outer space. Today, telescopes come in all shapes and sizes. Scientists are constantly finding new ways to make these instruments more powerful. In the next couple years, two new

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telescopes with different purposes are scheduled to see “first light.” (This is the phrase used by astronomers to talk about the first images produced by a telescope.)

One of four planned Pan-STARRS telescopes has been built atop a Hawaiian mountain. Pan-STARRS will image the sky every night in search of large, near-Earth asteroids. Brett Simison

One of the telescopes, called Pan-STARRS, could save humans from extinction. Nick Kaiser, a scientist who works on the project, says the Pan-STARRS telescope has been designed to find “90 percent of all killer asteroids, near-Earth asteroids bigger than 300 meters.” Smaller asteroids often crash into Earth, but if a giant “killer” asteroid were to strike our planet, it could mean the end of human civilization. Pan-STARRS, like most telescopes, uses mirrors and lenses to provide pictures of outer space. Giant mirrors are used to “gather” light. They reflect the light onto the lens of a camera, which can then record the image. When completed, Pan-STARRS will include four telescopes perched atop a mountain on the Hawaiian island of Maui. Only one telescope is in place and working now. Each telescope will take pictures of one patch of sky for about 30 seconds, and then move on to another patch. Every night, each telescope will take pictures of about 1,000 patches. Every week, each telescope will have photographed the whole sky. Each of the four telescopes will take pictures of the same patches of sky. One telescope, working alone, may occasionally malfunction and incorrectly detect an

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asteroid. If there are three other telescopes working, astronomers can use them to see if there really is an asteroid coming our way. By using four telescopes instead of one, scientists hope to get a more accurate picture of space. If a giant asteroid were identified, astronomers would plot ways to deflect it or break it up long before it reached Earth.

The European Space Agency's Gaia craft, scheduled to launch in 2011 and illustrated here, will spin as its two optical telescopes map the Milky Way in 3-D. Medialab

Another telescope, called Gaia, is being designed by astronomers in Europe — and it couldn’t be more different from Pan-STARRS. While Pan-STARRS will be looking for asteroids and comets headed for Earth, Gaia will be looking at our entire galaxy. Gaia is designed to draw a map of the Milky Way, our home galaxy. Just as a map of your town gives you a picture of where things are located, Gaia’s map of the galaxy will tell astronomers where the stars reside. Over five years, Gaia will observe about a billion stars and other objects in our galaxy. Each object will be observed about 70 times. Unlike Pan-STARRS, which will be constructed on firm Earth, Gaia will be launched into space strapped to a rocket. It consists of two telescopes, each focused at a different angle. These two telescopes act like Gaia’s “eyes.” The reason humans can see things in 3-D is that we have two eyes focused on the same object, at slightly different angles. (If you want to see a two-dimensional version of your world, try using just one eye.) By using two telescopes like eyes, Gaia can produce the first 3-D map of the positions of the stars it views.

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Gaia, which is scheduled to blast off in 2012, will be a powerful telescope. If you were to use it on Earth, for example, you could stand 600 miles away from your best friends and still get a crisp and clear picture of their hair. Gaia and Pan-STARRS are two of more than a dozen telescopes being designed by scientists right now. The next generation of telescopes will reveal new parts of our universe that will seem surprising, just as the Moon’s craters must have seemed when observed 400 years ago. The universe, with all its planets, stars and other strange objects, is a complicated puzzle with pieces that we can see by using powerful telescopes. Astronomers of the future will gaze deep into space, gather more pieces, try to put them together and ask new questions. The big question, however, will always be the same: “What’s out there?” Questions 1. How many years ago did Galileo first use his telescope? __________________________________________________________________ 2. What is mean by “first light”? __________________________________________________________________ __________________________________________________________________ 3. Pan-STARRS will be looking for ___________________ ___________________. 4. Gaia will be looking at our ___________________ ___________________. 5. What is the big questions that will always be asked by astronomers? __________________________________________________________________