What they do: Astronomers use their physics and math skills to study the universe and its origin, which includes galaxies, solar systems and the planets within.

他们的工作：天文学家利用他们在物理学和数学方面的能力来研究宇宙和它的起源，包括银河第、太阳系以及其中的行星。

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An estimated 99.85 percent of the mass of our solar system is contained within the Sun, while the planets collectively make up most of the remaining 0.15 percent.

太阳占据了太阳系总质量的大约99.85%，而在剩余的0.15%中，行星占据了大部分。

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Swarms of giant chunks of debris form within the disc, collide and merge - forming the Earth, moon and other planets.

这些巨大的碎石不断的挤压碰撞合并，最后形成了地球、月亮和其它行星。

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Dr Boss estimates that Nasa's Kepler mission, due for launch in March, should begin finding some of these Earth-like planets within the next few years.

BBC: Galaxy has 'billions of Earths'

This is easily enough to detect Jupiter-like planets around distant stars, and it should also be enough to detect smaller, Uranus-like planets around stars within the sun's stellar neighbourhood.

ECONOMIST: A roadmap for planet-hunting

By the time any change occurred, humans might even have generated technology that could speed up the Earth's rotation or transport us to other liveable planets within our galaxy.

BBC: Why the Moon is getting further away from Earth