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One of NASA's space telescopes has discovered what scientists believe may be the youngest planet ever spied -- a celestial body that at 1 million years old or less is a cosmic toddler.
In its first major findings, announced Thursday, the Spitzer Space Telescope also has shown that protostars, or developing stars, "are as common as the cicadas in the trees here on the East Coast" and that the planetary construction zones around infant stars have considerable ice that could produce future oceans.
"Oh, my goodness, it knocked our socks off," University of Wisconsin astronomer Ed Churchwell said of the trio of discoveries.
Spitzer is an infrared telescope has been orbiting the sun and studying the universe since last summer. It did not actually "see" the toddler planet, but yielded evidence that enabled scientists to infer its existence.
The object is in the constellation Taurus, 420 light-years away -- quite close by astronomy standards. It is believed to be on the inner edge of a planet-forming dusty disk that encircles a 1-million-year-old star.
University of Rochester astronomer Dan Watson said a sharply defined hole in the middle of the disk suggests that a planet created the opening. That gaseous planet would have been formed sometime since the star's formation.
By comparison, the Earth and the rest of the solar system are 4.5 billion years old. And up until now, the youngest planets observed around other stars were a few billion years old.
Astronomer Deborah Padgett at the Carnegie Institution of Washington cautioned that instead of a planet, the gap in the dusty disk could be caused by asteroid formation or a smaller unseen stellar companion. She said it is also possible that the heat and light of the star are forming the gap by blowing all the dusty material out.
However, she said that it is "very likely" a planet, and that additional research by Spitzer and future spacecraft should settle the debate.
The Hubble Space Telescope previously observed the star -- named CoKu Tau 4 -- but could not make out such details.
Watson also reported that for the first time, Spitzer has shown without ambiguity all the icy organic materials in the planet-forming disks surrounding infant stars, or those that are only hundreds of thousands of years old. He called these the building blocks of what might end up as a solar system like our own.
As for the proliferation of developing stars, Spitzer revealed more than 300 star formations in one region in the constellation Centaurus, 13,700 light-years away.
"It's kind of blown our minds," Churchwell said.
Anne Kinney, director of NASA's astronomy and physics division, likened the preponderance of protostars to the cicadas.
Spitzer is the fourth and final spacecraft in NASA's Great Observatory series, which began with Hubble and continued with the Compton Gamma Ray Observatory, now gone, and the Chandra X-ray Observatory.
The 14-year-old Hubble was the only one designed for astronaut repairs, and its future has ignited a fierce debate within and outside NASA. NASA has decided to forgo any more shuttle missions to Hubble, citing post-Columbia safety concerns, and instead may send robots on a life-prolonging mission.
On Thursday, a petition signed by 26 astronauts, most of them retired, was sent to President George W. Bush by Sen. Kay Bailey Hutchison. The astronauts -- "we, the real risk-takers" -- urged that the shuttle mission to Hubble be reinstated.
(China Daily via agencies, May 28, 2004)
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