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Venus and Antares

December 22, 2012

If you’re dreamin’ of a White Christmas, you don’t have to stay on Earth to find it. Snow also appears to fall on Mars. And you might even find some snow on Venus — not on its hellish surface, but in a layer of clouds about 75 miles high.

The Venus Express spacecraft has found evidence of that layer during its five years in orbit around our closest planetary neighbor. It found that a high-altitude layer of clouds is quite cold — cold enough for carbon dioxide to freeze and form small ice grains or snowflakes.

Even if they exist, though, the snowflakes won’t get anywhere close to the surface. For one thing, they’re sandwiched between cloud layers that are hundreds of degrees warmer. And even if they could get through those clouds, Venus’s surface temperature is more than 850 degrees Fahrenheit — an environment where you’re not likely to hear any sleigh bells in the snow.

Mission scientists are continuing to study the results to confirm the finding, and to learn what might be causing the cool-down high above the planet.

Venus is in view in the dawn sky right now, blazing forth as the brilliant “morning star.” The star Antares, the leading light of Scorpius, is close to its lower right tomorrow. They’re so low in the sky that Antares is tough to see through the early twilight, but its proximity to Venus will help you pick it out. Venus is sliding down toward the Sun, so it’ll stand side by side with Antares on Wednesday.


Script by Damond Benningfield, Copyright 2012

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