天文地质学（astronomical geology）

Text 4
"My very educated mother just served us nine pizzas." Many American school children are taught this sentence to help them remember the order of the planets of the solar system. Soon though, this may change because, on July 29th, a team of astronomers announced the discovery of a very distant celestial body larger than Pluto. The researchers claim that the new body--which they are informally calling Xena--should be classified as a planet.
The new body--temporarily named 2003UB313--orbits the Sun once every 560 years. It is currently over 14 billion kilometres away, about three times farther out than Pluto, making it the most distant object ever discovered in the solar system. The researchers think it is part of the Kuiper belt, a ring of rocky objects that extends beyond Neptune.
Mike Brown of the California Institute of Technology, Chad Trujillo of the Gemini Observatory and David Rabino witz of Yale University discovered the object in data recorded at the Palomar Ob servatory in San Diego in October 2003, but its motion did not become apparent until they reanalysed the data in January 2005.
The question of whether or not the new body should be considered a planet has rekindled the de bate over what exactly counts as a planet. A handful of objects of similar size to, but smaller than, Pluto have been discovered in the Kuiper belt over the past few years. These have not been considered planets, mainly because they were smaller than Pluto. But 2003 UB313 is larger than Pluto. If Pluto is a planet, shouldn’t it be as well
The case is not so clear cut. Many astronomers argue that Pluto should not be considered a plan et. It is more like a large asteroid, they hold. Meanwhile, Dr Brown asserts that as Pluto has historically been considered a planet, anything larger should also be considered one.
Ultimately, the International Astronomical Union, a group of professional astronomers, will end this existential anxiety. Dr Brown expects the process to take months, and the team is not allowed to reveal its suggested name until then. Since most Greek and Roman names have already been used, he and his colleagues have previously drawn upon Native American and Inuit mythology for names. He will only hint that the new name comes from a different tradition altogether.
Time will tell whether mother will be serving "nine polished xylophones", "nine pizzas" or just "noodles".

A:might be given by the International Astronomical Union. B:might be revealed by the research team soon. C:might be chosen from list of Greek and Roman names. D:might be chosen from Native American and Inuit myth.

Despite the fact that comets are probably the most numerous astronomical bodies in the solar system aside from small meteor fragments and the asteroids, they are largely a mystery. Scientists do not know exactly what comets are or where they come from. Educated guesses are the best we have in hand.
Considering the role of comets in legend and the memory of man, it is remarkable that we still know so little, relatively, about them. The most famous comet of all, Halley’s Comet ( named for the man who predicted its return), was first sighted by the Chinese in 240 B．C．, and it has returned to terrify the people of the world on a regular basis every since then. The ancient considered it an object of ill omen. By mysterious coincidence, the arrival of Halley’s Comet coincided with such events as the battle of Hastings in 1066, the Jewish revolt of 66 A．D．, and the last battle of Attila the Hun against the Romans. Nor is it the only comet to fill man with awe, but merely the most famous in a rich aristocracy of blood-freezers.
Comets are even more fascinating to amateur astronomers than to professionals, because this is one area where amateurs can make major discoveries. Comet Ikeya Seki, one of the brightest comets to appear in this century was discovered in 1965 by a pair of Japanese amateurs, Ikeya and Seki. The person who discovers a new comet gets his (or her) name put on it. And amateurs have a head start in the race to discover new comets; the shorter focal lengths on their smaller telescopes give them a positive advantage over the huge telescopes such as Mount Wilson which is built to scan for galaxies, not comparatively short distances.
Most scientists tend to agree with astronomer Fred T. Whipple that a comet is really a large mushy snowball of frozen ices and gases ( ammonia, methane, possibly carbon dioxide) with a few bits of solid particles stuck inside. But no one is sure how comets are created in the first place.
Scientist believe that comets don’t exhibit their characteristic tail while they lurk fat out in space away from the warmth of the sun but, rather, wander in the form of frozen lumps, like icebergs. This is the core of the comets. Only when the comet approaches the heat of the sun, does the ice begin to melt and stream away in the form of visible gases. The tails of the comets stream out behind for, literally, astronomical distances. Halley Comet had a tail of 94 million miles long when it visited here in 1910．The Great Comet of 1843 had a tail of 186 million miles long.
At the beginning of the text, the author indicates that______.

A:comets are the most commonly seen astronomical bodies B:comets, meteor fragments and the asteroids are mysterious C:not much is known about comets D:nothing do we know about comets except guesses

Text 4 "My very educated mother just served us nine pizzas." Many American school children are taught this sentence to help them remember the order of the planets of the solar system. Soon though, this may change because, on July 29th, a team of astronomers announced the discovery of a very distant celestial body larger than Pluto. The researchers claim that the new body--which they are informally calling Xena--should be classified as a planet. The new body--temporarily named 2003UB313--orbits the Sun once every 560 years. It is currently over 14 billion kilometres away, about three times farther out than Pluto, making it the most distant object ever discovered in the solar system. The researchers think it is part of the Kuiper belt, a ring of rocky objects that extends beyond Neptune. Mike Brown of the California Institute of Technology, Chad Trujillo of the Gemini Observatory and David Rabino witz of Yale University discovered the object in data recorded at the Palomar Ob servatory in San Diego in October 2003, but its motion did not become apparent until they reanalysed the data in January 2005. The question of whether or not the new body should be considered a planet has rekindled the de bate over what exactly counts as a planet. A handful of objects of similar size to, but smaller than, Pluto have been discovered in the Kuiper belt over the past few years. These have not been considered planets, mainly because they were smaller than Pluto. But 2003 UB313 is larger than Pluto. If Pluto is a planet, shouldn’t it be as well The case is not so clear cut. Many astronomers argue that Pluto should not be considered a plan et. It is more like a large asteroid, they hold. Meanwhile, Dr Brown asserts that as Pluto has historically been considered a planet, anything larger should also be considered one. Ultimately, the International Astronomical Union, a group of professional astronomers, will end this existential anxiety. Dr Brown expects the process to take months, and the team is not allowed to reveal its suggested name until then. Since most Greek and Roman names have already been used, he and his colleagues have previously drawn upon Native American and Inuit mythology for names. He will only hint that the new name comes from a different tradition altogether. Time will tell whether mother will be serving "nine polished xylophones", "nine pizzas" or just "noodles".

A:might be given by the International Astronomical Union. B:might be revealed by the research team soon. C:might be chosen from list of Greek and Roman names. D:might be chosen from Native American and Inuit myth.

We know less about the astronomical universe than we do about any social system because ______.

A:theories of its origin and history are varied B:our knowledge of it is highly insecure C:only a very. small sample of it has been observed D:few scientists are involved in the study of astronomy

Edwin Hubble Edwin Hubble changed our ideas about the universe and how it developed. The work of few other scientists changed our understanding of 【51】 suddenly. He made his most important discoveries in the 1920s. Today, other scientists continue the work he began back then. Edwin Powell Hubble was born in 1889 in Marshfield, Missouri. He 【52】 his early years in the state of Kentucky. Then he moved with his family to Chicago, Illinois. He attended the University of Chicago, taking mathematics and astronomy 【53】 his specialty. As a student, Hubble was also a member of the University’’s basketball team and an excellent boxer. Several people urged him 【54】 for the world heavy weight boxing championship after college. Instead he decided to continue his 【55】 . In his first observations from Mount Wilson, California, Hubble used a telescope with one-hundred fifty-two and began 【56】 more and more distant objects. His first great discovery was made 【57】 he recognized a Cepheid variable star. Cepheid variable stars are stars whose brightness changes at regular periods. Hubble then began to observe more details about galaxies. He studied their shapes and brightness. By 1925, he had made enough observations to say that the universe is organized into many shapes and sizes. As stars differ from one another, he said, 【58】 galaxies. According to his observations, the galaxies have a center, and arms of matter that seem to the center like a pinwheel. Other are shaped 【59】 baseballs or eggs. A few have no special 【60】 Hubble proposed a system to describe galaxies by their shape. His system is still used today. He also showed that 【61】 are similar in the kinds of bright objects they contain. All galaxies, 【62】 , are related to each other much as members of a family are related to each other. In the late 1920s, Hubble studied the movement of galaxies through space. His investigation led to the most important 【63】 discovery of the 20th century—the expanding universe. Hubbies discovery 【64】 a major change in our ideas of the universe. The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. The expanding often is 【65】 the Big Bang.

A:astronomical B:universal C:space D:heavenly

Edwin Hubble Edwin Hubble changed our ideas about the universe and how it developed. The work of few other scientists changed our understanding of 【51】 suddenly. He made his most important discoveries in the 1920s. Today, other scientists continue the work he began back then. Edwin Powell Hubble was born in 1889 in Marshfield, Missouri. He 【52】 his early years in the state of Kentucky. Then he moved with his family to Chicago, Illinois. He attended the University of Chicago, taking mathematics and astronomy 【53】 his specialty. As a student, Hubble was also a member of the University’’s basketball team and an excellent boxer. Several people urged him 【54】 for the world heavy weight boxing championship after college. Instead he decided to continue his 【55】 . In his first observations from Mount Wilson, California, Hubble used a telescope with one-hundred fifty-two and began 【56】 more and more distant objects. His first great discovery was made 【57】 he recognized a Cepheid variable star. Cepheid variable stars are stars whose brightness changes at regular periods. Hubble then began to observe more details about galaxies. He studied their shapes and brightness. By 1925, he had made enough observations to say that the universe is organized into many shapes and sizes. As stars differ from one another, he said, 【58】 galaxies. According to his observations, the galaxies have a center, and arms of matter that seem to the center like a pinwheel. Other are shaped 【59】 baseballs or eggs. A few have no special 【60】 Hubble proposed a system to describe galaxies by their shape. His system is still used today. He also showed that 【61】 are similar in the kinds of bright objects they contain. All galaxies, 【62】 , are related to each other much as members of a family are related to each other. In the late 1920s, Hubble studied the movement of galaxies through space. His investigation led to the most important 【63】 discovery of the 20th century—the expanding universe. Hubbies discovery 【64】 a major change in our ideas of the universe. The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. The expanding often is 【65】 the Big Bang.

A:astronomical B:universal C:space D:heavenly

Edwin Hubble Edwin Hubble changed our ideas about the universe and how it developed. The work of few other scientists changed our understanding of 【51】 suddenly. He made his most important discoveries in the 1920s. Today, other scientists continue the work he began back then. Edwin Powell Hubble was born in 1889 in Marshfield, Missouri. He 【52】 his early years in the state of Kentucky. Then he moved with his family to Chicago, Illinois. He attended the University of Chicago, taking mathematics and astronomy 【53】 his specialty. As a student, Hubble was also a member of the University’’s basketball team and an excellent boxer. Several people urged him 【54】 for the world heavy weight boxing championship after college. Instead he decided to continue his 【55】 . In his first observations from Mount Wilson, California, Hubble used a telescope with one-hundred fifty-two and began 【56】 more and more distant objects. His first great discovery was made 【57】 he recognized a Cepheid variable star. Cepheid variable stars are stars whose brightness changes at regular periods. Hubble then began to observe more details about galaxies. He studied their shapes and brightness. By 1925, he had made enough observations to say that the universe is organized into many shapes and sizes. As stars differ from one another, he said, 【58】 galaxies. According to his observations, the galaxies have a center, and arms of matter that seem to the center like a pinwheel. Other are shaped 【59】 baseballs or eggs. A few have no special 【60】 Hubble proposed a system to describe galaxies by their shape. His system is still used today. He also showed that 【61】 are similar in the kinds of bright objects they contain. All galaxies, 【62】 , are related to each other much as members of a family are related to each other. In the late 1920s, Hubble studied the movement of galaxies through space. His investigation led to the most important 【63】 discovery of the 20th century—the expanding universe. Hubbies discovery 【64】 a major change in our ideas of the universe. The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. The expanding often is 【65】 the Big Bang.

A:astronomical B:universal C:space D:heavenly