";?> Learn English Online - Free Audio Course - Unit 37: Short Talk - Planetology
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Unit 37: Short Talk - Planetology


1.) What did astronomers think in the past?
a) there were probably more planets
b) Earth was the only planet with life
c) stars were far away

2.) What has changed in astronomy?
a) astronomers look more closely
b) there is better technology to find planets
c) the telescopes are not broken

3.) How did they know the difference between a star and a planet?
a) the planets would make small movements
b) the colors were different
c) the stars could not be seen with a telescope


Good morning everyone. My name is Professor Michael Andrews. On behalf of myself and my colleagues, I would like to welcome you to Extrasolar Planetology, which is a new class being offered by the Astronomy Department this year.

About twenty-five years ago, there was no solid proof that other planets existed beyond our solar system. Most astronomers at that time felt that planets had to be out there, but they could not see them or prove they were there. Why? Simply put, planets are small and space is vast. Imagine trying to see a pea with a telescope from a hundred miles away, and you'll understand how hard it is to find planets that are light years distant.

Clearly, something changed, for we now have a class called Extrasolar Planetology. What changed? Well, mainly, instruments got better and sophisticated telescopes were put into space. As a result, astronomers began to find the proof that they had lacked before.

The very first good evidence for the existence of other planets came from observations of 'wobbling' stars. Using their high-tech instruments and space-based telescopes, astronomers found that some stars wobbled as they moved through space. What could be causing this the astronomers wondered? And then Eureka! The only likely explanation seemed to be that these stars were being affected by the gravity of unseen orbiting companions. In other words-planets!

And now, if you would please turn off the lights, I would like to show you some slides of a few of these wobbling stars.