리스닝 강의 지문이고 혜성(comets) 관련 내용이에요.
Professor: Today, I want to focus on the orbits of comets. We differentiate between comets
by their type of orbit, whether they are short period or long period orbits. Short period comets
generally remain within our solar system and have very stable orbits that allow us to predict
the length of their orbit and when they will return. Long period orbits are very eccentric and it
takes them at least 200 years and even upwards of a thousand years to fly back towards the
sun.
Let's talk about perhaps the most famous of short period comet, Halley's Comet. Halley's
Comet is a short period comet that passes by the sun once every 75 years. It has a stretched
out and elongated orbit that's very different from the circular orbit of the earth. At its closest
point to the sun, it is actually 1/2 the distance from the sun that the Earth is. At its furthest
point, it's almost 3,500 times as far from the sun as Earth is. As it gets closer to the sun, the
sun's immense gravitational pull speeds the comet up and the heat from the sun will vaporize
some of the ice and dust on the comet. Every time the comet passes the sun it gets smaller
and smaller. But how is ti that Halley's Comet has not yet been consumed by the sun? The
answer to that is that Halley's Comet was not always a short period comet but was captured
in the past.
Many long period comets originate from the Oort Cloud and they have extremely long orbital
paths. Because these comets' orbits cover unimaginable distances, it may take tens of
thousands of years for the comet to return. So, Scientists rarely track the paths of long
period comets. So, how does a long period comet turn into a short period comet? Well, we
have many other planets in our solar system and these planets all have their own gravitational
pulls. So if a long period comet happens to pass by, let's say Jupiter, in just the right way,
then the gravitational pull of Jupiter may be just enough to capture the comet and bring it
into a shorter orbit around the sun.
1. According to the professor, how are comets influenced by the sun? Click on 2 answers.
A. some of the solid material of the comet is vaporized by the sun.
B. The sun's gravity alters the velocity of the comet.
C. Parabolic orbits are bent into periodic orbits by the sun.
D. The sun causes the comet to go towards unknown areas of the solar system.
B랑 D가 답이라고 되어 있는데 B는 답이라는 것을 쉽게 알겠는데 A는 답이 안 되는 건가요?
그리고 D는 강의 내용 어디에서 찾을 수 있는 건지를 모르겠네요. 근거가 안 나오는 것 같은데...
그리고 저는 지문에 밑줄 쳐 놓은 내용이 답 A,B에 해당된다고 생각해서 골랐거든요.
A의 경우 solid material이 조금 맘에 걸리긴 했지만 상대적으로 맞는 얘기 같아서 선택했거든요.
만약에 답 D가 맞는 거라면 주어진 강의의 어디에 근거가 있는 걸까요?