Venus and Saturn

StarDate: September 16, 2013

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Two cloudy, windy planets huddle close together in the early evening sky right now. Venus is low in the west-southwest as the sky begins to darken. It’s the brilliant “evening star,” so you can’t miss it. And tonight, Saturn stands just above it. Saturn is only about one percent as bright as Venus, so it’s more difficult to spot through the twilight. But its proximity to Venus will help you pick it out.

Saturn is the second-largest planet in the solar system — a ball of gas that’s almost 10 times as wide as Earth. It’s topped by clouds that form globe-circling bands. Winds in these bands can reach hundreds of miles per hour.

So can the winds in the upper atmosphere of Venus — and that’s a big puzzler.

Venus is a ball of rock that’s about the same size as Earth. It has a hot, dense atmosphere that’s completely blanketed by clouds.

Clouds at the top of the atmosphere blow around the planet in just four days — an average speed of about 200 miles per hour. Yet it takes about eight months for Venus to make one turn on its axis. That’s the equivalent of clouds blowing all the way around Earth in just a few minutes. So far, though, scientists can’t explain why Venus’s clouds move so fast.

To complicate the picture, the speed is increasing. The Venus Express spacecraft has shown that the average wind speed around the planet’s middle has jumped by about 60 miles per hour since 2006 — adding to the mystery of Venus’s windy skies.

 

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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