How Rare Is the Earth?

September 18, 2008
By Edna DeVore, Co-Investigator, Education and Public Outreach, Kepler Mission & Director of Education and Outreach, SETI Institute

Is the Earth a rare place in our galaxy, or are Earth-like planets as common as stars? Scientists do not yet have the data to answer this question, but should get it through NASA's upcoming Kepler Mission. Personally, I find the Kepler Mission to be inspiring. With this space mission, we're taking a big step on the quest to understand our place in the universe.

It's been about four centuries since Copernicus, Kepler and Galileo began to displace the Earth from the center of the universe. Less than one hundred years ago, we discovered that the sun was not near the center either, and that theMilky Way galaxy was just one of billions of galaxiesand that the universe has no center. We've come a long way on our quest, and now the Kepler Mission will search for hard evidence of other Earths. We don't know whether to expect that Earth is rare or common.

What do you think about the search for extrasolar planets? NASA's Kepler Mission team would like to know, and so would the Smithsonian Air and Space Museum. On the Kepler Mission "Names in Space" web page, you are invited to submit a short statement (up to 500 words) about the Kepler Mission and its search for other Earths. We'd like to hear your opinion about the significance of this project and its search. You are also invited to submit your name, city, state and country. Once registered, you will be able to download a Kepler Mission certificate of participation from the website.  (No SPAM: Email addresses are NOT collected.)

The names and statements of all participants will be burned onto a DVD, and launched into space on board the Kepler spacecraft next spring.  The information will also be provided to the Smithsonian Air and Space Museum as a historical document of public opinion about the mission and space exploration.

There's a deadline to get on board: November 1, 2008. 

What do we know today? Astronomers have discovered more than 300 planets orbiting nearby stars, some in multiple planet systems. The number rises each week, and you can install a handy widget on your desktop to keep you informed about the latest extrasolar planet count, courtesy of JPL's PlanetQuest program. So far, giant planets dominate the list of discoveries because they can be found using ground-based telescopes. Small, Earth-sized planets are lost in the noise of the observational data. To be sure, there have been recent announcements of "super-Earths" in short-period orbits, hot planets of several Earth-masses. No comfy Earth-like worlds have yet been identified.

NASA's Kepler Mission has the sensitivity and precision to discoversmall planets, and determine whether they are in the habitable zone. The results will help answer the question: "Are Earth-like planets rare, or common?"

That's a great question. For me it's a wonderful adventure to be a part of this mission. What about you? What's your opinion? If you are an educator, what do your students think about the search for other Earths? Join us, and send your name and opinion into space.

If you'd like more information about the Kepler Mission before tapping your keyboard to convey your thoughts, please visit: http://Kepler.NASA.gov.