Exoplanets: Top 10 Questions

October 2010

Thanks to Dr. Mark Kuchner, Planetary Scientist, NASA Goddard Space Flight Center for the answers.

1: Is there life on other planets? Could there be another Earth?

We don't know if there is life on other planets yet, but maybe someday we will. There are planets that are similar to Earth. These planets have similar size and mass. Their orbit to the stars is like our orbit to the sun, and maybe they even have similar atmospheres. (From Amber in Mrs. Hunt's class at Cynthia Mann Elementary School in Boise)

2: How do you find new planets?

We have an ever-expanding collection of tools that we use to find new planets. One is the Radio Velocity Technique. Here, we look at a star that is being orbited by a planet. Based on the light spectrum, we can determine if it is moving closer to us or further away. Another technique that has become popular is the Transit Technique. This method blocks out some of the light from a star. When we see the change in a star's brightness, it tells us that there is a planet orbiting the star. A third technique is the Direct Detection. This method can be challenging as planets do not emit very much light. However, a cornograph, used inside a telescope, can enable us to detect planets. (From Megan in Mrs. Schweitzer's class at Riverside Elementary School in Boise)

3: How far are exoplanets?

We don't know how far the farthest one out is, but we have seen planets that are orbiting stars that are as close as only several light years away, maybe 20 or 30 light years away. Meaning, it takes them 20 or 30 years for their light to get to us. That's a short distance to astronomers. With techniques like Kepler, we're looking at stars that are halfway across the galaxy. They may be a thousand times farther away than that. (From Ting-Hsuan in Mrs. Schweitzer's class at Riverside Elementary School in Boise)

4: How do they figure out what to name the planets like Gliese 581G?

Planets are named after the stars they orbit. We look the stars up in a catalog and they usually have a number. That number becomes the name of the planet. Often, it takes a while to be certain a planet really is a planet. (From Gabrielle in Mrs. Hudson's class at Dalton Elementary School in Dalton Gardens)

5: Is Pluto considered an exoplanet?

Pluto is in our own solar system, so it orbits the sun. We consider it a dwarf planet, not an exoplanet. (From Ashley in Mrs. Wheeler's class at Five Mile Prarie Elementary School in Spokane)

6: How long would it take to get to the nearest exoplanet?

For now, we can't get to the nearest exoplanet. The nearest planet is about 20 or 30 light years away, so if we were traveling at the speed of light (186,000 miles per second), then we wouldn't get there for 20 or 30 years. What we mostly think about is not traveling to the exoplanets, but sending and receiving messages from them. (From Emma in Mrs. Hudson's class at Dalton Elementary School in Hayden)

7: What's in between solar systems?

In between solar systems is a lot of empty space. This space doesn't even have air in it. So, if you went there, you would suffocate because there is so little of anything in it. It's really, really empty. (From Jacey in Mrs. Woodall's class at Dalton Elementary School in Dalton)

8: Who discovered the first exoplanet?

The first exoplanet was discovered around a pulsar. A pulsar is like the nucleus of an atom, but it's huge, the size of a star. This discovery was made by Wolshan and Frail in the early 1990s. (From Bailee in Mrs. Woodall's class at Dalton Elementary School in Dalton)

9: Is there a star bigger than the sun?

There are many stars bigger than the sun. The sun is kind of small as far as stars go. There are stars that are so big, if you put one in the middle of our solar system, it would extend all the way out to Earth or even Jupiter. (From Ingrid in Mrs. Edlemier's class at Ustick Elementary School in Boise)

10: What holds the planets in place?

Gravity holds the planets in place. They are all whirling around the sun, and they are held in orbit because of the tremendous pull of the sun's gravity. (From Eva in Mrs. Angie's class at Longfellow Elementary School in Boise)

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