问答题
In recent decades, space-based observations have led
astronomers to change their previous view that Pluto was the ninth planet in the
solar system. By a strong majority, the International Astronomical Union voted
to change the definition of what it means to be a planet. The new definition
states that, in order to be called a planet, an object must meet three criteria.
First, it must orbit the sun. Second, it must be large enough to have a round
shape due to the force of its own gravity. Third, it must dominate the
neighborhood of its orbit by clearing the region of other large
bodies. Pluto meets the first two criteria. It orbits the sun,
is round in shape, and has an estimated diameter of 2,400 kilometers. However,
Pluto does not meet the third criterion because it does not dominate the region
of its orbit. As a planet forms, it becomes the strongest gravitational body in
its orbit, and this gravity causes it to sweep up asteroids, comets, and other
debris around it. Pluto's orbit remains crowded with other objects, many of
which are nearly as large as Pluto itself. The new definition of planet is clear
and precise, and Pluto does not qualify. Astronomers now agree
that Pluto is not a true planet. Instead, Pluto and its moons are part of a
collection of objects called the Kuiper Belt. Astronomers have redefined Pluto
as a dwarf planet, an object too small to be a real planet but too large to be a
space rock. Unless Pluto gains mass by crashing into and absorbing the other
objects in its orbit, it will remain a dwarf planet and not a true
planet. Now listen to the recording. When you hear the
question, begin your response. You may look at the reading passage during the
writing time. Summarize the points made in the lecture, being
sure to explain how they contradict specific points made in the reading passage.
【正确答案】Key points:
The lecture states that the decision to change Pluto's status was controversial; scientists disagree about the decision. This contradicts the point in the reading that the decision was reached by a strong majority vote.
The lecture states that critics think the new definition of planet is not adequate or realistic. This contradicts the point in the reading that the new definition is clear and precise.
The lecture states that calling Pluto a dwarf planet causes controversy and confusion. This contradicts the point in the reading that astronomers agree that Pluto is a dwarf planet and not a true planet.
【答案解析】[解析]
Okay, you've all read about how Pluto is no longer a planet. Well, let me offer another view. First of all, you should know that the decision by the International Astronomical Union was not unanimous. In fact, the vote was controversial, and there is a lot of scientific disagreement about the decision to change Pluto's status. Several scientists maintain that Pluto is indeed a planet. Pluto orbits the sun, has enough gravity to pull itself into a ball, and has its own satellites--moons. While its orbit isn't completely clear of debris, Pluto is still the biggest body in its neighborhood.
Second, about the new definition of planet, well, critics don't find it to be adequate or realistic. They believe that, instead of narrowing the definition, it should have been widened to include Pluto and similar bodies. Our solar system is complex. It contains countless objects of all sizes. The definition of planet should include any large body that revolves around the sun and is not itself a satellite of another planet. This broader definition would make full-fledged planets of 50 or more additional objects in the solar system.
Finally, calling Pluto a "dwarf planet" causes controversy and confusion. Why is a dwarf planet not a real planet? The astronomer's union did not consider the historical and cultural role that Pluto has played. For 80 years, children have learned about the nine planets in our solar system. Saying that Pluto is not a real planet confuses both teachers and students. It has forced us to go back and rewrite textbooks, redraw charts, and rebuild museum exhibits.
Summarize the points made in the lecture, being sure to explain how they contradict specific points made in the reading passage.