Tuesday, December 20, 2011
NASA’s Kepler space telescope has found the first confirmed Earth-size planets orbiting another star, astronomers announced Tuesday, a major milestone in an ongoing project aimed at finding out how commonplace — or rare — Earth-like worlds may be across the cosmos.
In a solar system 1,000 light years away with at least five planets, the newly confirmed Earth-size worlds orbit too close to their star to support life. But proving the Kepler observatory can, in fact, spot worlds as small as Earth across the vast reaches of interstellar space gives astronomers confidence many more such planets are awaiting discovery in the 2,326 planet candidates found by the telescope to date.
“The first of these two planets has a diameter just 3 percent larger than the Earth, which makes it the closest object to the Earth in terms of size in the known universe,” Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, told reporters in a teleconference. “The second planet is 13 percent smaller than the Earth, with a diameter of around 7,000 miles. It is also smaller than Venus, and this is, in fact, the smallest planetary body ever discovered in orbit around an Earth-like star.
“Most importantly, it is the first time we’ve crossed the Earth-size threshold. In other words, December 2011 could be remembered as the first time humanity has been able to detect a planet of Earth-size or smaller around another star.”
Thursday, December 8, 2011
NASA’s Mars Exploration Rover Opportunity has found bright veins of a mineral, apparently gypsum, deposited by water. Analysis of the vein will help improve understanding of the history of wet environments on Mars.
“This tells a slam-dunk story that water flowed through underground fractures in the rock,” said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Opportunity. “This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can’t be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It’s not uncommon on Earth, but on Mars, it’s the kind of thing that makes geologists jump out of their chairs.”
The latest findings by Opportunity were presented Wednesday at the American Geophysical Union’s conference in San Francisco.
The vein examined most closely by Opportunity is about the width of a human thumb (0.4 to 0.8 inch, or 1 to 2 centimeters), 16 to 20 inches (40 to 50 centimeters) long, and protrudes slightly higher than the bedrock on either side of it. Observations by the durable rover reveal this vein and others like it within an apron surrounding a segment of the rim of Endeavour Crater. None like it were seen in the 20 miles (33 kilometers) of crater-pocked plains that Opportunity explored for 90 months before it reached Endeavour, nor in the higher ground of the rim.
Last month, researchers used the Microscopic Imager and Alpha Particle X-ray Spectrometer on the rover’s arm and multiple filters of the Panoramic Camera on the rover’s mast to examine the vein, which is informally named “Homestake.” The spectrometer identified plentiful calcium and sulfur, in a ratio pointing to relatively pure calcium sulfate.
Tuesday, December 6, 2011
For the first time, astronomers using NASA’s Kepler space telescope have confirmed a roughly Earth-size planet orbiting a sun-like star in the so-called “Goldilocks” zone where water can exist in liquid form on the surface and conditions may be favorable for life as it is known on Earth.
Along with the confirmed extra-solar planet, one of 28 discovered so far by Kepler, researchers today also announced the discovery of 1,094 new exoplanet candidates, pushing the spacecraft’s total so far to 2,326, including 10 candidate Earth-size worlds orbiting in the habitable zones of their parent stars.
Additional observations are required to tell if a candidate is, in fact, an actual world. But astronomers say a planet known as Kepler-22b, orbiting a star some 600 light years from Earth, is the real thing.
“Today I have the privilege of announcing the discovery of Kepler’s first planet in the habitable zone of a sun-like star, Kepler-22b,” Bill Borucki, the Kepler principal investigator at NASA’s Ames Research Center, told reporters. “It’s 2.4 times the size of the Earth, it’s in an orbital period (or year) of 290 days, a little bit shorter than the Earth’s, it’s a little bit closer to its star than Earth is to the sun, 15 percent closer.
“But the star is a little bit dimmer, it’s a little bit lower in temperature, a little bit smaller. That means that planet, Kepler-22b, has a rather similar temperature to that of the Earth…If the greenhouse warming were similar on this planet, its surface temperature would be something like 72 Fahrenheit, a very pleasant temperature here on Earth.”
It is not yet known whether Kepler-22b is predominantly rocky, liquid, or gaseous in composition, but the finding confirms for the first time the long-held expectation that Earth-size planets do, in fact, orbit other suns in the habitable zones of their host stars.
That, in turn, greatly improves the odds for the existence of life, as it is commonly defined, beyond Earth’s solar system.
Full article: http://news.cnet.com … suns-habitable-zone/