Great discovery - maybe

Hey, isn't the big question, are we alone? And isn't one of the key questions relating to that is Earth unique?

If so, this latest research discovery is far more significant than all of the other discoveries we've seen recently about planets orbiting other stars because up until now all they have seen is gas giants like Jupiter. Now they claim to have spotted an earth-like planet.

That said, the research leaves me a little less than overwhelmed. The detection process is esoteric - an Einstein gravitational lens effect caused by something as small as a relatively small planet. But obviously people who know alot more than I do have confidence in this technique. The rationale for asserting that this means Earth-like planets are common is something anyone can understand. The discoverers argue that such a planet would only be discovered if they were relatively common - otherwise the odds against discovery are too great.

OK - but what if they just happened to win the lottery? I mean the odds are incredibly ridiculous when it comes to wining the lottery, but people do win it.

That said, the New York Times account of the discovery can be found here and this will be carried by "Nature" today and I'm sure reported more widely.

That said, as I read this story the research seemed tenuous and the basis for assertion that this means Earth-like planets are common - hey, maybe they just won the lottery - a bit dicey. Still, I found it very interesting:

The New York Times
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January 26, 2006
Search Finds Far-Off Planet Akin to Earth
By DENNIS OVERBYE

Now you see it, now you don't.

Astronomers say that by virtue of the ceaseless shifting of the billions of stars in the Milky Way and a trick of Einsteinian physics, they have briefly glimpsed the most Earth-like planet yet to be discovered outside the solar system. It is a ball of rock and ice only about 5.5 times as massive as Earth, smaller than any of the 160 previously discovered exoplanets, and is orbiting a dim reddish star 21,000 light-years from here.

The discovery, the researchers say, suggests that rock-ice planets like our own are predominant in the cosmos. That bodes well for future planet-hunting missions from space like the Terrestrial Planet Finders at NASA.

The distant planet manifested itself as a brief flash: As it passed at night in front of an even more distant star, its gravity focused and momentarily brightened the star's light.

It was all over in less than a day, a cosmic blink of an eye.

"It was the blip in the night that we have been waiting for," said Jean-Philippe Beaulieu of the Institut d'Astrophysique de Paris, who led an international collaboration of 73 astronomers. They reported their findings yesterday at a news conference in Washington and are publishing them today in the journal Nature.

Alan P. Boss, a planetary theorist at the Carnegie Institution of Washington, said in an e-mail message that the discovery was "a big one." Another expert who took no part in the research, Geoffrey W. Marcy of the University of California, Berkeley, said, "The result looks solid to me, and perhaps the planet is, too."

The planet, smaller than Neptune and dubbed OGLE-2005-BLG-390Lb, resides about 234 million miles from its star. At that distance, its surface temperature would be minus 370 degrees Fahrenheit, Dr. Beaulieu said.

The work was largely that of two large teams that have built far-flung observing networks to exploit a feature of Einstein's general theory of relativity. The theory says a massive object can act as a gravitational lens, bending and magnifying the light from more distant objects in space.

One team, the Optical Gravitational Lensing Experiment, or OGLE, led by Andrzej Udalski of Warsaw University, has been set up to monitor the brightness of millions of Milky Way stars every night from a telescope in Chile, so as to catch fluctuations caused by the passage of intervening objects of various kinds: dim stars, so-called dark matter objects or planets.

Last July, alerted by the OGLE team that such a lensing event was under way, Dr. Beaulieu's team, Planet (for Probing Lensing Anomalies NETwork), sprang into action to do high-resolution observations. On Aug. 9, that team recorded a tiny blip on a much larger blip that was caused by the passage of an unseen star, the planet's parent, in front of the more distant star. That tiny blip was the planet itself.

As Dr. Beaulieu explained in an e-mail message, it would have been much easier to see a giant gaseous type of planet. The long odds against detecting so small a planet as the new one argues for its commonness.

"If only a small fraction of the stars had such planets, we would have never detected this small planet," Dr. Beaulieu said.

Scott Tremaine, a theorist at Princeton, said, "The results suggest that rock-ice planets must be more common than gas giants."

* Copyright 2006The New York Times Company

Greg Stone