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Venus and Saturn

October 29, 2016

Two planets are slipping past each other in the early evening sky. Venus is the “evening star” — the brightest object in the night sky other than the Moon. Saturn stands to the upper right of Venus this evening, and a bit farther from it on succeeding nights. It’s not nearly as bright, but its proximity to Venus should help you find it.

The appearance of these worlds is an illusion. Saturn is actually the more impressive of the two. It’s the second-largest planet in the solar system — about 10 times Venus’s diameter. It looks fainter only because it’s hundreds of millions of miles farther.

And it’s that distance that allowed Saturn to grow so big.

Venus is the second planet out from the Sun. So it was born in the hottest part of the young solar system. Radiation and a “wind” of charged particles from the Sun cleared much of the planet-building materials from this region. All that was left were chunks of rock and metal. Many of these coalesced to make Venus and the other small inner planets, including Earth.

Saturn was born much farther from the Sun. In that zone of cold and darkness, the rock was supplemented by chunks of ice. That allowed Saturn to build a big, heavy nucleus. As the core took shape, its gravity pulled in vast amounts of hydrogen and helium left over from the birth of the Sun, surrounding Saturn with a thick envelope of gas. So Saturn grew to giant proportions — while Venus stayed nice and small.


Script by Damond Benningfield

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