NASA Podcasts

What's Up for January 2012?
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What's up for January? Evolving planets.

Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in Pasadena, California.

Like people, planets grow old. Instead of wrinkles, many have craters. And rather than becoming frail, rocky planets cool and shrink.

Features on Mars resembling dry riverbeds and the discovery of minerals that form in the presence of water, have led planetary scientists to envision a younger Mars that was warmer and wetter.

Water that once flowed across the surface evaporated or became trapped below the surface or in polar ice caps.

Elsewhere, the interiors of Mercury and our Moon have cooled significantly.

As they cooled they shrank, leading to lines of cliffs -- or scarps -- that formed as the surface contracted and buckled.

Venus and Jupiter rule the early evening sky this month. And Mars brightens and now rises in the late evening, before midnight at the beginning of the month and by 8:30 at month's end.

Saturn rises around midnight, but it's best seen near dawn.

The rings are open wider now, showing a 15-degree tilt.

The January Quadrantid meteor shower on the 4th peaks just as the Moon sets near midnight.

You can also spot an asteroid this month. Eros is visible in the eastern sky below the constellation Leo.

In 1998 NASA's NEAR-Shoemaker probe flew by Eros, orbited it in 2000, and soft-landed on the asteroid in 2001.

You can learn more about our evolving planets at, for Year of the Solar System.

And you can learn about all of NASA's missions at

That's all for this month. I'm Jane Houston Jones.

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