Many Earths?

TED (Technology Entertainment and Design) is a global set of conferences run by the American private non-profit Sapling Foundation. It was formed to disseminate “ideas worth spreading.” Since 2006, the talks conducted at these conferences have been offered for free viewing online through Currently, there are about 700 of these talks available on the site conducted by leading scientists, authors, and artists on topics ranging from space exploration, mathematics, and literature to television and movies. Each presenter is allowed 18 minutes to share their ideas in the most innovative and engaging way that they possibly can. Past presenters have included Bill Gates, Richard Dawkins, Jane Goodall, the founders of Google, many Nobel Prize winners, and even former President Bill Clinton. More than 290 million people have taken advantage of watching these video presentations.

About two years ago, TED released a video of a talk done by Astronomer Dimitar Sasselov. He is a professor of astronomy at the Harvard University and director of the Harvard Origins of Life Initiative. In 2002 he led a team that discovered, at the time, the most distant planet in the Milky Way galaxy, OGLE-TR-56b, a planet in the constellation Sagittarius. It is slightly larger than Jupiter and is 4900 light years away from us. It was discovered by means of the transit method—that is, by seeing the dip in the light output of its star as it passed in front of the disc of its sun. The discovery of OGLE-TR-56 was then confirmed by the Doppler technique. The Doppler technique detects the change in the wavelength of the light put off by the star as it is pulled back and forth by the planet as it orbits around the star. The same principle causes the change in the tone of a train’s whistle as it approaches you as you stand on a train station or wait for it to pass at a road crossing.

Dimitar Sasselov is also one of the lead scientists involved with the Kepler Mission, a NASA space observatory launched on March 7, 2009 which is designed to discover Earth-like planets in Earth-like orbits around other stars.

According to Sasselov in his TED talk this July, Kepler’s mission has been wildly successful.

He announced that in the first sixty days of the mission he and the other scientists have already discovered “hundreds” of planets that are the size of Earth, in orbits that are at an “Earth-like” distance from their stars. Moreover, he announced that based on this preliminary evidence, there must be at least 100 million planets like Earth in the Milky-way Galaxy. Although the information at this point is preliminary, given that the mission of Kepler is designed to last for another couple of years, the data so far collected is clear enough.

Between 1995, when the first extra-solar planet was discovered and the 2009 launch of Kepler, about 400 planets had been found around other stars. Nearly all of those planets, due to the nature of the methods used, had been large gas giant planets like Jupiter, Saturn, Uranus and Neptune. Kepler has changed all that. Now, rocky, Earthlike planets are in the majority. A more complete picture is emerging and it turns out that the shape of our solar system is apparently the norm in the universe.

Kepler’s discoveries at this point are still subject to further analysis and verification. And even once these apparent discoveries are confirmed, it does not mean that scientists have determined that there are a hundred million planets in our galaxy that have life as Earth has life, or that have civilizations as Earth has civilizations. It doesn’t even mean that they know these planets have water on them. Kepler can only tell us the size and orbital characteristics of these “Earth-like” planets.

It will take future space probes with better telescopes to discover what the surface temperatures of these newly discovered worlds are, and what gases make up their atmospheres. If we find any of these planets have atmospheres like Earth’s—with oxygen, carbon dioxide and water vapor, along with evidence of photosynthesis—then we’ll know for sure that there is at least some sort of life out there. If we find the equivalent of smog or other industrial pollutants or artificial chemicals, that would be obvious indications of intelligent life. But if the intelligent beings on those planets are still living in pre-industrialized societies—of the sort we had up until the early 1800’s—then from interstellar distances we will never be able to tell that they are there.

Nevertheless, given the new realities of the number of planets that we now know are out there, that potentially could be comfortable places to live, it would be irrational to imagine that none of them harbor intelligent living beings.

Up until a couple of years ago we could only speculate about the existence of Earthlike planets. Now we finally know that they are out there.

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About R.P. Nettelhorst

I'm married with three daughters. I live in southern California and I'm the interim pastor at Quartz Hill Community Church. I have written several books. I spent a couple of summers while I was in college working on a kibbutz in Israel. In 2004, I was a volunteer with the Ansari X-Prize at the winning launches of SpaceShipOne. Member of Society of Biblical Literature, American Academy of Religion, and The Authors Guild
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