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Name _____________________________________________________________

Asteroids and Comets and

Meteors, Oh My!

(source Astronomy Picture of the Day) (source NASA Galileo)

(source lxixixl)

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Asteroids, Comets, Meteor0ids (an activity from spaceday.org)

What is considered a small body? Any object in the sky that is smaller than a planet or a moon, such as an asteroid, a comet, or a meteoroid What are some things scientists want to know about small bodies? Their size and shape Their composition (what substances they contain) Their origin (where and how they were formed) Their location (where to find them)

Asteroid Size and Shape: Irregular, rocklike fragment; from a few meters up to 1,000 kilometers in diameter Composition: Rock containing carbon; a few have iron and other metals Origin: Leftover material from formation of solar system Location: Most found between orbit of Mars and Jupiter (Asteroid Belt) Famous Example: An asteroid’s crashing to Earth formed Chicxulub crater in Mexico’s Yucatan Peninsula; it is thought to be responsible for extinction of

dinosaurs Comet Size and Shape: Nucleus (center) up to 20 kilometers in diameter; surrounded by gas (two tails, one gas and one dust, which are millions of kilometers long) Composition: Ice, rock, ammonia and other gases Origin: Leftover material from formation of solar system Location: They enter the solar system from deep space, orbit near sun, then

move far out into space again Famous Examples: Comet Halley, Comet Hale-Bopp

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Meteoroid Size and Shape: Irregular, rocklike fragment; a few centimeters up to a few

meters in diameter Composition: Rock, iron, or a combination of both Origin: Most are broken pieces of asteroids; a few are comet dust (called

meteors if they enter Earth’s atmosphere) Location: If they enter Earth’s atmosphere and hit the ground, they are

meteorites Famous Example: Iron meteorite found by Mars Exploration Rover Opportunity

(first ever found on another planet) Materials Meter stick Glue stick Scissors Two paper clips Unlined paper Materials

Safety Concerns: Scissors. Use scissors in the appropriate manner. Procedure 1. Get a plain sheet of white paper and turn it sideways. 2. Measure four equal strips of paper, each 2-inches wide. 3. Cut strips (see diagram). 4. Select one of the paper strips; starting at end of strip, use metric ruler to measure 0.5 cm along length of strip. 5. Draw line on strip at ¼-inch and cut off the ¼-inch section; this represents the scaled size of a meteoroid; glue the strip to the Data Sheet in the space provided.

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6. Starting at the end of strip where the cut was made, repeat the process, but this time measure ¾-inch; again, draw a line at ¾-inch and cut off the ¾-inch section; this section represents the scaled size of a comet; glue it to the Data Sheet too. 7. Repeat the process, except this time measure a line that is 40-inches in length (you will need to measure more than one strip). 8. When done, cut at 40-inches; attach strips together by barely overlapping end of one strip to end of next and gluing or taping overlapped ends together; these strips represent the scaled size of an asteroid. 9. Glue the bottom strip to the Data Sheet in the space provided; neatly fold remaining strips back and forth over the bottom strip; use a paper clip to hold remaining strips in place. Creating Shapes and Makeup 1. On each white strip, sketch the small body it represents (use the information at the beginning of the worksheet as a reference); you may extend the comet’s two tails beyond the strip if you want, but be sure that you only draw on the top strip for the asteroid). 2. Now, illustrate the composition of each (see information at the beginning of the worksheet); decide which materials would be good examples of the material (for example, a comet has an icy center; items that are white or look like ice would be good to use in the middle of your comet drawing). Making Comparisons 1. Based on your scale model, which two small bodies are most similar in size? __________________________________________________________________ __________________________________________________________________ 2. Name two ways the compositions of asteroids, comets, and meteoroids are alike. a. b.

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Data Sheet

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It was on a dark and starry night of New Year’s Day, 1801. Giuseppe Piazzi, an Italian monk, was at work in his observatory on Sicily. He was a member of the Celestial Police. This was a group of astronomers looking for a missing planet between

Jupiter and Mars. That night he was confirming and cataloging stars in Taurus. While checking other astronomers’ work, he saw a tiny point of light. He thought it was just a dim star no one had cataloged. He checked for it the next night, but it had moved! He watched it move on January 3 and 4. What he was observing was not a star! He wrote to Johan Bode and told him what he had found; Bode was certain he had found “the missing planet.”

And the Plot Thickens . . . Cloudy weather set in. Piazzi was so sick that he could not observe the skies on some January nights. By January 24, he realized what he had discovered. He wrote a friend: “I have announced the star as a comet. But the fact that the star is not accompanied by any nebulosity [clouds of dust and gas] and that its movement is very slow and rather uniform has caused me many times to seriously consider that perhaps it might be something better than a comet. I would be very careful, however, about making this conjecture [this idea] public.” He wrote to Bode the next day. He did not receive the letter until March 20. When the letter reached Bode, he studied his star maps. He convinced Piazzi that he had found

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the “missing planet.” Piazzi named the object Ceres. Piazzi’s friend, Baron von Zach announced the discovery in his Monthly Correspondence summer of 1801. Piazzi tried to predict Ceres’ orbit. Astronomers need this information so they could try to find it. He observed Ceres for six weeks. He did not have enough information to determine Ceres’ orbit. After that, others searched for Ceres in vain. Several astronomers tried to work out Ceres’ orbit from his data. They each came up with different results. Ceres appeared to be lost. No one could verify Piazzi’s observations. But Carl Friedrich Gauss, a young German mathematician, came to the rescue! In October 1801, he applied his new method of “determining the path of a celestial body” to Ceres’ orbit. With surprising speed and accuracy, Gauss used Piazzi’s observations to predict where the new “planet” should be found. Imagine Gauss’s excitement when Baron von Zach found Ceres on the night of December 7, just where Gauss said it would be!

Actually, von Zach found four stars at that location, but when the weather cleared again on December 18, one of the stars was gone. Von Zach finally confirmed that he had recovered the missing object on January 1, 1802, exactly one year after Piazzi’s first sighting. Using Gauss’ results, Wilhelm Olbers, an amateur astronomer in Bremen, also found Ceres with his telescope.

Piazzi received a letter sent by the secretary of state on behalf of the king of Sicily commending him on the discovery of Ceres. Instead of giving Piazzi a medal, the king agreed to buy the Palermo Observatory a new telescope. Von Zach had two roles in this exciting event. He not only found the missing Ceres, but also, his publication, Monthly Correspondence, played a vital communication role in the recovery. By 1809, Gauss had refined the mathematical procedure he used to determine Ceres’ orbit, and it became the standard procedure for orbital calculations. The “missing planet” was found, lost, and found again. All’s well that ends well…except this was not the end! This was only the beginning! Many more asteroids had yet to be discovered. The NASA Dawn mission will travel to Ceres but first will study another asteroid named Vesta

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1. When and where did Giuseppe Piazzi live and work? __________________________________________________________________ 2. What was Piazzi doing when he saw a new point of light? __________________________________________________________________ __________________________________________________________________ 3. What was different about the point of light that he discovered on New Year’s Night, 1801? __________________________________________________________________ 4. What did Johann Bode think that Piazzi had discovered? __________________________________________________________________ 5. Why did Piazzi not think that the moving point of light he had discovered was a comet? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 6. Who finally announced that Piazzi had discovered the “missing planet”? __________________________________________________________________ 7. Why was the discovery of Ceres not substantiated during the six weeks of Piazzi’s observations? __________________________________________________________________ __________________________________________________________________

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8. How much time elapsed between Ceres’ first discovery and its rediscovery? Who was involved in the rediscovery? __________________________________________________________________ 9. What two important roles did Baron von Zach play in the rediscovery of Ceres? Explain why each was important. a. ___________________________________________________________ __________________________________________________________________ __________________________________________________________________ b. ___________________________________________________________ __________________________________________________________________ __________________________________________________________________ 10. Why was communication between astronomers and mathematicians so important in the rediscovery of Ceres? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I have discovered it!) but 'That's funny...'

-Isaac Asimov Select and answer one of the following in the space below. (Your response must be complete, neatly written, and fully cover the topic. A sentence or two will not adequately answer the question): The telescope was invented nearly 200 years before the first asteroid discovery.

How was the invention of the telescope instrumental to the work of the Celestial Police?

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Discuss the advantages of forming a group like the Celestial Police. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________

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Comet Facts, Myths, and Legends (from NASA - Space Science: Adventure Is Waiting/Hubble – Amazing Space)

The word "comet" comes from the Greek word for "hair." Our ancestors thought comets were stars with what looked like flowing hair trailing behind.

For centuries, scientists thought comets traveled in the Earth's atmosphere. In 1577, observations by Danish astronomer Tycho Brahe showed that they actually traveled far beyond the moon.

Sir Isaac Newton (1642-1727), the great English scientist, discovered that comets move in elliptical (egg-shaped) orbits around the Sun. He also thought that comets were members of the Solar System, just like planets, and that they could return over and over again. He was right!

As early as the 1700's, scientists began developing mathematical formulas that could predict the orbit of a particular comet around the Sun. At that time, calculators and computers didn’t exist, so everyone had to do the calculations by hand!

Most astronomers in the 1500's and early 1600's thought that a comet came once and was never seen again. They believed that a comet approached the Sun in a straight line, spun around it, and then disappeared into space in a straight path.

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People did not always know what comets were. In ancient times, people thought comets were "power rays" of supernatural beings. They thought comets contained fire because they were so bright in the sky.

Some people in ancient times thought that a comet was a curse. To save himself from the "curse of the comet," Emperor Nero of Rome had all possible successors to his throne executed

In 1910, people panicked when a comet passed through Earth’s path around the Sun. In Chicago, people sealed their windows to protect themselves from the comet’s poisonous tail. Others committed suicide. Special "Comet Protecting Umbrellas," gas masks, and "anti-comet pills" were sold.

Not everyone saw comets as bad luck. Some thought they brought good luck. They also believed that comets carried angels through the heavens.

People have known about comets, unlike other small bodies in the Solar System, since ancient times. The Chinese recorded visits by Halley's Comet as far back as 240 B.C.

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The famous Bayeux Tapestry, which commemorates the Norman Conquest of England in 1066, depicts an image of Halley's Comet bright in the sky before the Battle of Hastings. Some people thought this meant that King Harold would lose his throne to William, the Duke of Normandy. He did!

Edmund Halley of England studied comets and developed a theory suggesting that those sighted in 1531, 1607 and 1682 were actually the same object. He was the first to successfully predict the comet’s next appearance in 1758, but he died 16 years before the comet returned.

Halley’s Comet reappears every 76 years. Its next appearance is in 2061. Maybe you will see it return! Here’s a good picture of the comet.

Comets leave a trail of debris behind them. If their path crosses Earth's path, then at that point, every year for a long time, there will be meteor showers as the long-gone comet's debris strikes our atmosphere. Some of these meteor showers occur every year when the Earth passes the place where the comet had been long ago. The Perseid meteor shower occurs every year between August 9 and 13 when the Earth passes through the orbit of the Swift-Tuttle comet. Halley's Comet is the source of the Orionid shower in October.

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Comets are brightest when they are near the Sun.

Did comets kill the dinosaurs? Sixty-five million years ago, 70 percent of all species then living on Earth disappeared within a very short time. This included the last of the great dinosaurs. One possibility is that a comet about 10 kilometers in size struck the Earth. Scientists think that the impact disrupted the environment by displacing great amounts of dirt and rocks into the air.

The explosion that this object must have caused was similar to the explosion a rock the size of Mount Everest, traveling 10 times faster than the fastest bullet, would cause if it hit the Earth. There is a 65-million-year-old crater from an impact of similar magnitude just off the coast of Mexico in the Yucatan Peninsula.

NASA knows of no asteroid or comet currently on a collision course with Earth. The probability of such a collision is quite small. In fact, as far as we can tell, no large object is likely to strike Earth any time in the next several hundred years.

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Comet Hale-Bopp On July 23, 1995, an unusually large and bright comet was seen outside of Jupiter's orbit by Alan Hale of New Mexico and Thomas Bopp of Arizona. Careful analysis of Hubble Space Telescope images suggested that its intense brightness was due to its exceptionally large size. While the nuclei of most comets are about 1.6 to 3.2 km (1 to 2 miles) across, Hale-Bopp's was estimated to be 40 km (25 miles) across. It was visible even through bright city skies, and may have been the most viewed comet in recorded history. Comet Hale-Bopp holds the record for the longest period of naked-eye visibility: an astonishing 19 months. It will not appear again for another 2,400 years Comet Swift-Tuttle 1992

This comet was first seen in July 1862 by American astronomers Lewis Swift and Horace Tuttle. As Comet Swift-Tuttle moves closer to the Sun every 120 years, it leaves behind a trail of dust debris that provides the ingredients for a spectacular fireworks display seen in July and August. As Earth passes through the remnants of this dust tail, we can see on a clear night the Perseid

meteor shower. Comet Swift-Tuttle is noted as the comet some scientists predicted could one day collide with Earth because the two orbits closely intercept each other. The latest calculations show that it will pass a comfortable 24 million km (15 million miles) from Earth on its next trip to the inner Solar System. Comet Hyakutake On January 30, 1996, Yuji Hyakutake (pronounced "hyah-koo-tah-kay"), an amateur astronomer from southern Japan, discovered a new comet using a pair of binoculars. In the spring of that year, this small, bright comet with a nucleus of 1.6 to 3.2 km (1 to 2 miles) made a close flyby of Earth — sporting one of the longest

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tails ever observed. The Hubble Space Telescope studied the nucleus of this comet in great detail. This is not Comet Hyakutake's first visit to the inner Solar System. Astronomers have calculated its orbit and believe it was here about 8,000 years ago. Its orbit will not bring it near the Sun again for about 14,000 years. Comet Halley

Comet Halley is perhaps the most famous comet in history. It was named after British astronomer Edmund Halley, who calculated its orbit. He determined that the comets seen in 1531 and 1607 were the same objects that followed a 76-year orbit. Unfortunately, Halley died in 1742, never living to see his prediction come true when the comet returned on Christmas Eve in 1758. Each time this comet's orbit

approaches the Sun, its 15-km (9-mile) nucleus sheds about 6 m (7 yards) of ice and rock into space. This debris forms an orbiting trail that, when falling to Earth, is called the Orionids meteor shower. Comet Halley will return to the inner Solar System in the year 2061. Comet Shoemaker-Levy 9

Between July 16 and July 22, 1994, more than 20 fragments of Comet Shoemaker-Levy 9 collided with the planet Jupiter. Astronomers Carolyn and Eugene Shoemaker and David Levy discovered the comet in 1993. The Hubble Space Telescope took many spectacular pictures of this event as the comet's pieces crashed into Jupiter's southern hemisphere. It was the first collision of two Solar System bodies ever to be recorded. The impacts created atmospheric plumes many thousands of kilometers high that showed hot "bubbles" of gas with large dark "scars" covering the planet's sky.

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Vocabulary Asteroid — A small object composed rock. Many of these objects orbit the Sun between Mars and Jupiter. Their size can range anywhere from 10 yards to 500 miles in diameter. Coma — The cloud of gas and dust that forms around a comet's nucleus. Comet — A “dirty snowball” consisting of ices, rocks, and dirt. Dust Tail — Forms when the solar wind separates dust from the coma, pushing it outward away from the Sun. Gas-Ion Tail — Forms when the solar wind separates gases from the coma, pushing them outward away from the Sun. Inner Solar System — The path of the Solar System between the Sun and the orbit of Jupiter Meteor —A grain of sand to large boulder traveling through the atmosphere. Meteor Shower —Many meteors are seen in the night sky as a result of the Earth passing through the former path of a comet. The debris released by the comet causes the meteor shower. Meteorite —Any part of a meteor that hits the Earth’s surface. Meteoroid —Boulders to dirt particles that are in space. Naked-eye Visibility —Being able to see a celestial object, such as a comet, without the aid of telescopes, binoculars or other astronomical devices. Comet Nucleus —The solid icy/rocky part of a comet. Orbit —The path followed by body around another, such as Earth’s path around the Sun or the Moon’s path around Earth. Period —The time needed for one complete trip or cycle. For example, the period for the Earth to travel around the Sun is 365 days. Solar Wind —A stream of charged particles ejected from the surface of the Sun.

Myths vs. Reality - Comets Myth Comets come from regions outside the Solar System. Reality Comets are part of the Solar System. Scientists believe they come from one of two locations within the Solar System: the Kuiper belt and the Oort cloud. The comets that

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we see often – every 100 years – come from the Kuiper belt, and comets that we see rarely – every few thousand years – come from the Oort cloud. Myth Comets are composed of the same material as asteroids. Reality Although comets and asteroids are both tiny bodies that orbit in the Solar System, their composition is different. Asteroids are mostly rock with some ice, while comets are mostly ice with some rock. Myth Comets always have tails. Reality Comets do not always have tails. They develop a fuzzy, shell-like cloud called a coma, and one, two, or three tails when near the Sun. Comets have no coma or tail when far away from the Sun. Myth All comets look the same and don't change their appearance. Reality Comets have a coma and one, two, or three tails when near the Sun, and no coma or tail when far away from the Sun. (A coma is a cloud of gaseous material surrounding the nucleus.) Myth Pluto is the most distant and last object in the Solar System.

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Reality Beyond Pluto's orbit is a group of icy objects known as the Kuiper Belt, from which short- period comets emerge. Farther still is a sphere of icy bodies, called the Oort Cloud, from which long-period comets emerge. Short-period comets visit the inner Solar System frequently, while the long-period comets visit infrequently. Myth There is empty space between the planets. Reality There is gas and dust, also known as the interplanetary medium, between the planets. Comets are responsible for depositing some of the gas and dust found in the inner Solar System.

Identifying Comets 1. Identify a fact associated with comets. __________________________________________________________________ __________________________________________________________________ 2. Identify a myth associated with comets. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 3. Comets are small Solar System objects, yet ancient cultures knew about them. Identify one property of comets that explains why humanity has known of comets for so long. __________________________________________________________________

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__________________________________________________________________ 4. Describe the path of a comet and explain how this affects its reappearance. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 5. Short-period comets (orbital periods of less than 200 years) tend to come from the Kuiper Belt—a region beyond the orbit of Neptune similar in shape to the asteroid belt. Long-period comets (orbital periods of more than 200 years) tend to come from the Oort Cloud—a spherical region well beyond the orbits of Neptune and Pluto. Based on the reading, explain where each of the following comets is likely to have originated. Explain your answer. a. Hale-Bopp – __________________________________________________ _____________________________________________________________ b. Swift-Tuttle – ________________________________________________ _____________________________________________________________ c. Hyakutake – __________________________________________________ _____________________________________________________________ d. Halley’s – ____________________________________________________ _____________________________________________________________

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Based on your reading of “Comet Facts, Myths, and Legends,” would you say the following statements are true or false?

Statement True False1. It's possible that a big comet striking the Earth

killed off the dinosaurs.

2. Only a professional astronomer with a powerful telescope can discover a new comet.

3. About 100 years ago, some people bought comet-protecting umbrellas and anti-comet pills to protect themselves.

4, The closer a comet is to the Sun, the brighter it will appear.

5. The ancients thought comets were the power rays of supernatural beings.

6. A meteor shower occurs when many comets at once pass over the Earth.

Ten Important Comet Facts Created for Deep Impact Mission Maura Rountree-Brown Educator/Student - Enrichment 1. Comets are in orbit around the Sun as are our planets. 2. Comets are composed of ices, dust and rocky debris carried from the early formation of the solar system about 4.5 billion years ago.

3. Comets are remnants from the cold, outer regions of the solar system. They are generally thought to come from two areas - the Oort Cloud and the Kuiper Belt. Both of these are areas where materials left over from the formation of our solar system have

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condensed into icy objects. Both regions extend beyond the orbits of Neptune and Pluto but are still part of our solar system and much closer to us than the closest star. 4. Comet orbits are elliptical. It brings them close to the sun and takes them far away. 5. Short period comets orbit the Sun every 20 years or less. Long period comets orbit the Sun every 200 years or longer. Those comets with orbits in between are called Halley-type comets. 6. Comets have three parts: the nucleus, the coma and the tails. The nucleus is the solid center component made of ice, gas and rocky debris. The coma is the gas and dust atmosphere around the nucleus, which results when heat from the Sun warms the surface of the nucleus so that gas and dust spew forth in all directions and are driven from the comet's surface. The tails are formed when energy from the Sun turns the coma so that it flows around the nucleus and forms a fanned out tail behind it extending millions of miles through space. 7. We see a comet's coma and tail because sunlight reflects off the dust (in the coma and dust tail) and because the energy from the Sun excites some molecules so that they glow and form a bluish tail called an ion tail and a yellow one made of neutral sodium atoms. 8. Scientists have seen comets range in size from less than 1 km diameter to as much as 300 km, although the 300km (called Chiron) does not travel into the inner solar system. 9. We know a comet could impact Earth and that it is important to understand the nature of comets so we can design better methods to protect ourselves from them should one be on a collision path with Earth. 10. A comet nucleus has a dark, sometimes mottled surface but we don't know if it has an outer crust or if it is layered inside. We don't really know what comets are like beneath their surface and that's why we need a mission like Deep Impact. Select and answer three of the following comet misconceptions. In the space below, explain why these are misconceptions. (Your response must be complete, neatly written, and fully cover the topic. A sentence or two will not adequately answer the question): Comets are in the atmosphere (i.e. flash across the sky quickly).

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Comets are the same as meteors. Comets are hot balls of fire, or at least the tail is a ball of fire. Comets consist of a bright tail only. Comets are made of rock and iron. Some comets are not in orbits.

__________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________

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Asteroid, Comet, or Meteor? Place an “X” in the appropriate boxes to indicate characteristics of asteroids, comets, and meteors.

Asteroid

Comet

Meteor

Made of ice, dust, and gas.

Appears as a streak in the sky.

Made of rock and/or metal.

Orbits the Sun.

Often called “shooting stars.”

Sometimes called a “dirty

snowball.”

Orbits between Mars and Jupiter.

Most are found in the Oort Cloud or

Kuiper Belt.