An artist's illustration of an Earth-like planet. The search for planets that are similar to Earth is one of NASA's main goals. Many planets have already been discovered orbiting other stars, but so far only larger planets (the size of Jupiter or larger) have been found. New missions are being planned by NASA which will be able to detect smaller Earth-sized planets. Some of these missions will also try to detect signs of life on these planets by studying emissions in their atmospheres.


Astronomers find possible rocky planet

SOURCE: San Francisco Ghronicle
Keay Davidson, Chronicle Science Writer
Thursday, August 26, 2004

Earth-like orb spins too close to its star to be habitable

What might be the first known "Earth-like" planet orbiting a star like our own sun has been reported by European astronomers.

The discovery, if verified by further observations, unveils "a new class of planets" and points to a fresh stage of astronomical research, one that is profoundly relevant to the quest for extraterrestrial life, said Alan Boss of Carnegie Institution in Washington, D.C.

That stage is one about which science-fiction buffs have long dreamed: the detection of faraway planets that, like Earth, are relatively small, rocky bodies where plants and creatures might evolve.

"It looks to me like the first discovery of an extrasolar terrestrial- type planet!!" said an excited e-mail message to The Chronicle from Boss, who was not involved in the discovery but is one of the world's leading authorities on planetary formation. An extrasolar planet orbits a star other than our sun.

The planet is too small to be seen directly. The discovery, made by Nuno C. Santos of Portugal and 15 colleagues from France, Switzerland and Chile, was hastened by the development of a sophisticated new telescope that detects slight shifts in the star's motions as it is nudged back and forth by the tiny planet's gravitational pull.

Their find is suspected of being a rocky body that, like Earth, has an iron core. Although perhaps up to 14 times as massive as Earth, it is by far the smallest known planet yet seen that orbits a yellow, "G"-type star similar to our sun.

Another leading expert, Timothy Brown of the National Center for Atmospheric Research in Boulder, Colo., called Wednesday's news "really exciting. The people that do this (research) are among the best anywhere. ... The evidence (for a rocky planet) looks persuasive."

Inevitably, laypeople ask astronomers whether new extrasolar planets supply evidence for the possibility of alien life, Brown noted with a chuckle. Astronomers have long assumed that life, if it exists elsewhere, almost certainly evolved on a rocky surface like Earth's.

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