Team Spots Earth-Like Planet

By Lee Bowman SCRIPPS HOWARD NEWS SERVICE

An icy, probably rocky ball detected near the Milky Way’s center by an international network of telescopes is the most Earth-like planet yet found outside our solar system, scientists reported today.

Astronomers have recorded more than 150 planets beyond our neighborhood in the past decade or so. But all of them are Jupiter- sized or larger (Jupiter has the mass of 317 Earths) — so large that their gravitational pull causes the stars they orbit to wobble, giving their existence away to human observers.

But the new planet, located in the constellation Sagittarius, has about 5{ times the mass of Earth and a relatively cool parent star that it circles about every 10 Earth years, according to a report on the discovery published in the journal Nature.

Also, the scientists report, the planet’s distance from its sun is more than three times what Earth’s is from its sun.

“This planet is actually the first and only planet that has been discovered so far that is in agreement with the theories for how our solar system formed,” said Uffe Grae Jorgensen, an astronomer with the Niels Bohr Institute in Copenhagen, Denmark, and a member of the discovery team.

Researchers don’t think the planet can sustain life, given that it has an estimated surface temperature of minus-364 degrees Fahrenheit, about the same as Pluto’s. While it may have a thin atmosphere, the planet’s rocky surface is probably covered with deep frozen oceans.

“This is an important breakthrough in the quest to answer the question ‘Are we alone?’ ” said Michael Turner, assistant director for mathematical and physical sciences at the National Science Foundation, a sponsor of the research.

More than 73 scientists from 32 institutions took part in the study. For many of the researchers, the most exciting result was proving that their search technique, called gravitational microlensing, could find such a small planet.