MeteorsAsteroidsComet Home PageSOLAR SYSTEM SMALL BODIES
Click on one of these topics to see questions related to that topic:
| Meteors |
Asteroids |
| Comet |
Home Page |
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
Q1. What is the difference between a primitive meteorite and a differentiated one? Give an example of each. Answer
Q2. What is meant by the term "primitive meteorite"? How can they be used to determine the age of the solar system? Answer
Q3. Describe what is happening when we observe a typical "shooting star" in the night sky. Answer
Q4. Describe the three basic types of meteorites. Answer
Q5. What do we see when a small meteor enters the atmosphere? What is happening to cause this? Answer
Q6. Describe the three types of meteorites. What is the significance of the existence of chondrules in some meteorites? Answer
Q7. How do we know that the material in a cabonaceous chondrite has never been geologically altered? Why is that important? Answer
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
Q1. What are the similarities and differences between asteroids and comets? Where do the comets we see come from? Answer
Q2. How can the chemical composition of an asteroid be determined from ground-based observations? Answer
Q3. How can the size and shape of an asteroid be determined from ground-based observations? Answer
Q4. Why do most asteroids occur in a narrow belt in the solar system? Answer
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
Q1. What are the similarities and differences between asteroids and comets? Where do the comets we see come from? Answer
Q2. Why do comets have a relatively short lifetime? Where do the comets we see today come from? Answer
Q3. Describe the three parts of a comet, when the comet is close to the sun. Answer
Q4. What are the differences between long period comets and short period comets? Answer
Q5. Where do the comets we see come from? Answer
Q6. What are the two types of tails a comet may have? Why do they point away from the sun? Answer
Q7. Describe the properties and appearance of the nucleus of a comet. Answer
Q8. Describe the Oort cloud. What is its significance? Answer
Q9. Describe the appearance of a comet when it is close to the sun. How does the sun affect the appearance? Answer
Q10. Describe the three components of a comet when it is close to the sun. Answer
Q11. Why must there be a reservoir of comets? Answer
Q12. Describe the Kuiper Belt. What is believed to be the origin of comets in the Kuiper Belt? Answer
Q13. Compare and contrast the Kuiper belt and the Oort cloud. Answer
Q14. What direction does the tail of a comet point? Why? Answer
Q15. Why is it important to send satellites to study comets instead of just observing them from Earth? Answer
Q16. Describe the properties of the nucleus of Halley's Comet, as observed by the Giotto spacecraft. Answer
Q17. Describe the orbits and origin of short period and long period comets. Answer
Meteors Answers
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
A1. A primitive meteorite is one whose material has never been melted. Its composition reflects whatever small grains were present during its formation. Small chondrules within the meteorite are the remains of the dust particles out of which it formed. Many stony meteorites, including the carbonaceous chondrites, are primitive meteorites. A differentiated meteorite is one that comes from a body large enough to have chemically differentiated into an iron core and a rocky mantle. The obvious example of a differentiated meteorite is the iron class meteorites.
A2. A primitive meteorite is one that has never been completely melted. Thus, the material inside it has been preserved since the material in the solar system began to form into solid bodies. Primitive meteorites are identified by the presence of chondrules inside them, which are the rounded grains of dust out of which the solar system began to form.
These primitive meteorites can be used to determine the age of the solar system by finding some radioactive material inside the meteorite. By measuring the ration of the radioactive material to its decay product, we can determine how long that material has been locked inside the meteorite. Since the meteorite has not been melted or altered since the beginning of the solar system, this determinations tells us the age of the solar system.
A3. A shooting star is a small bit of rock which enters Earth's atmosphere at high speed and burns up due to the friction it experiences as it moves through the atmosphere. We see the hot air left behind the moving meteor.
A4. The 3 types of meteorites are: (1) stony (composed mostly of rocky material but often containing small bits of metallic material), (2) iron (almost pure iron alloy), and (3) stony-iron (a roughly 50-50 mix of rock and metal).
A5. When a small meteor enters the atmosphere, the friction it experiences with the upper atmosphere heats it and vaporizes it. The column of hot air created by the passing meteor is visible as a bright streak of light which moves rapidly across the sky.
A6. Stony meteorites are composed predominantly of rocky material, although most of them have small pieces of metallic iron embedded in them. Iron meteorites are essentially pure metallic iron-nickel. Stony-iron meteorites are an equal mix of metal and rock. The stony meteorites are by for the most common type of meteorite.
Chondrules are small roundish inclusions in some stony meteorites. They are the partially melted remains of the original grains of dust from which all objects in the solar system formed. Hence, they represent the oldest, most primitive material available for study in the solar system.
A7. Carbon compounds are easily destroyed at even moderate temperatures. If the material in a carbonaceous chondrite meteorite had ever been subjected to any significant geologic process, the carbon compounds would have evaporated and been lost. The absence of such events in the past history of a meteorite tells us that it is unaltered since the formation of the solar system. These objects give us direct information about the conditions in the solar nebula as the solar system formed.
Asteroids Answers
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
A1. Asteroids are rocky bodies, mostly in nearly circular orbits between Mars and Jupiter. Comets are icy bodies, usually observed in highly elongated orbits. Comets that we see come from either the Kuiper Belt (a donut-shaped ring in the plane of the solar system) or the Oort Cloud ( a large spherical cloud outside the solar system).
A2. The chemical composition of an asteroid can be found by comparing the spectrum of reflected sunlight from the asteroid to the reflected spectrum of various meteorites on Earth. When a good match is found, we know the composition of the asteroid is similar to that of the meteorite.
A3. There are two ways to find the shape of asteroids. If several people observe the passage of the asteroid in front of a star, their separate measurements of when the star disappeared and reappeared tell us what the size and shape are. If an asteroid passes close to Earth, radar waves can be bounced off the asteroid. The returning waves tell us the size and shape of the asteroid.
A4. Most asteroids lie in orbits just inside the orbit of Jupiter. They are small bodies which were prevented from ever collecting together because of the disturbing influence of Jupiter's force of gravity. Jupiter's influence kept their orbits "churned up," so that gentle collisions which build larger bodies did not happen as often.
Comet Answers
***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question***
A1. Asteroids are rocky bodies, mostly in nearly circular orbits between Mars and Jupiter. Comets are icy bodies, usually observed in highly elongated orbits. Comets that we see come from either the Kuiper Belt (a donut-shaped ring in the plane of the solar system) or the Oort Cloud ( a large spherical cloud outside the solar system).
A2. Every time a comet comes close to the sun, more of the frozen gases evaporate from the nucleus and are lost to space. After just a hundred passes around the sun, most comets will have completely dissipated. Since comets have relatively short lifetimes when their orbits bring them close to the sun, there must be a reservoir of comets in orbits that always remain outside the solar system. These reservoirs are called the Kuiper Belt (a donut-shaped zone of comets just outside the orbit of Neptune) and the Oort Cloud (a spherical cloud of comets that stretches halfway to the nearest star).
A3. Comets consist of a nucleus (a small solid ball of dirty ice), a coma (a large, thin, roughly spherical ball of gas and dust which have evaporated from the nucleus and surround it), and a tail (gas and dust which have been blown out of the coma and trail away in the direction opposite to the sun).
A4. A short period comet has an orbit around the sun of less than 200 years while a long period comet takes more than 200 years to orbit the sun once.
A5. Comets come from either the Kuiper belt (a donut shaped cloud of comets in orbits from the outer edge of the planetary orbits out to a few hundred AU) or the Oort cloud (a spherical cloud of comets that reaches 100,000 AU or more from the sun).
A6. The dust tail is driven away from the comet by radiation pressure from the sun. It gently curves as the orbit of the dust particles slowly falls behind the comet. The ion tail is driven away from the comet by the solar wind of particles streaming away from the sun. Since both tails are driven away from the comet by forces coming from the sun, they both point generally away from the sun.
A7. The nucleus of a comet is small (generally only a few miles across), irregular in shape, and very dark (reflecting only a few % of the light which strikes its surface).
A8. The Oort cloud is a spherical swarm of cometary nuclei in roughly circular orbits at distances from a few hundred to several hundred thousand astronomical units from the sun. If one of these objects is disturbed from its circular orbit and falls into the solar system, it will appear to us as a long period comet when it is close to the sun.
A9. When close to the sun, a comet consists of a tiny, solid nucleus surrounded by a large spherical gaseous coma with a long gas and dust tail that stretches away from the sun. The light of the sun works to heat the nucleus of the comet, causing some of the ice in the nucleus to evaporate. The evaporating ice also releases some of the dust trapped in the ice. These released materials form the coma and tail of the comet.
A10. A comet near the sun consists of a tiny (5-10 mile) solid nucleus surrounded by a huge (100,000 mile) coma of gas and dust which has evaporated from the nucleus, with a long (millions of miles) tail of gas and dust streaming away from the coma in the direction away from the sun.
A11. Each time a comet passes near the sun, some of its gas evaporates. After about 100 passes, a typical comet will have completely evaporated and disintegrated. If there was not a reservoir of comets outside the solar system continually supplying fresh comets to the solar system, they would have long ago vanished from our part of the solar system.
A12. The Kuiper Belt is a donut-shaped ring of comets that exist in nearly circular orbits just outside the solar system. The Kuiper Belt extends from just outside Neptune’s orbit for a few hundred astronomical units. Comets in the Kuiper Belt are believed to have formed there, in the outer fringes of the disk from which all objects in the solar system formed.
A13. The Kuiper belt is a fairly flat distribution of comets in the plane of the solar system from just outside the orbit of Pluto to a few hundred AU. The Oort cloud is a spherical distribution of comets which lie many thousands of AU's from the sun.
A14. The tail of a comet points generally away from the sun because it is formed of matter that is pushed away from the comet by the light and wind of matter flowing from the sun.
A15. When comets approach the sun they are hidden inside a veil of evaporated gases that prevent us from directly observing the solid nucleus. Nuclei are so small that they would be hard to study from Earth even if we could see them. And comet nuclei are covered by a layer of dark material that prevents us from directly studying the main body of the nucleus.
A16. The nucleus of Halley's Comet is about 5 x 10 miles in size and covered with a very dark substance. Two large jets and several smaller jets of evaporating gas were seen.
A17. Long period comets originate in the Oort cloud at distances of a few tens of thousands of AU. Their very elongated orbits have random orientations compared to the plane of the solar system. Short period comets originate in the Kuiper belt a few hundred AU from the sun and have orbits aligned approximately with the plane of the solar system. Their orbits have usually been modified by a close gravitational interaction with Jupiter.