NASA Podcasts

What's Up for May 2012?
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What's up for May? A solar eclipse and 400 years of sunspots.

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

A unique annular solar eclipse occurs on May 20 for lucky observers in a path from Eureka, California, to Lubbock, Texas.

The rest of the United States will see a partial solar eclipse.

An annular eclipse occurs when the moon is at its farthest distance from Earth in its monthly orbit. At this time, the moon appears smaller than the sun, covering only 94 percent of the sun's disk.

The sun will appear as a bright ring, or annulus, around the dark silhouette of the moon.

No matter where you view from, you'll need a low western horizon to see this sunset eclipse.

The exposed ring of sunlight will be bright and you'll need to view using solar-safe telescopes or projection methods.

Though only six percent of the sun's surface will be visible at greatest eclipse, it will still be 60,000 times brighter than the full moon and will damage your eyes if you look directly at it.

The hours leading up to the eclipse are a perfect time to view sunspots and other features through safe solar telescopes.

The first sunspots were observed nearly 3,000 years ago, but an English monk, John of Worcester, made the earliest existing drawings of sunspots in 1128.

Galileo's solar observations, exactly 400 years ago in 1612, were made at the same time of day, every day. So he was able to track the motion of the spots across the disk of the sun.

The movement of the sunspots allowed early astronomers to estimate the sun's rotation period, which is about 27 days.

NASA's Ulysses and TRACE spacecraft have completed their mission studying the sun.

The two STEREO spacecraft launched in 2006 to see the structure and evolution of solar storms as they blast from the sun and move through space.

And SOHO has been studying the sun from its deep core to the outer corona and the solar wind since 1995.

The Solar Dynamics Observatory, or SDO, is currently observing the sun in many wavelengths. It's the first mission to be launched for NASA's Living with a Star program. SDO will study how solar activity is created and how space weather comes from this activity.

In the night sky, watch Venus drop in altitude all month long. Through a telescope you'll see a slender crescent.

Mars and Saturn remain great viewing targets all month long, too.

You can read about this month's solar system theme 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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