NASA finds Earth-size planets outside solar system

NASA discivers Earth- size planets

Source:Yahoo!7
Reuters
December 21, 2011, 7:44 am

     Super moon photo

WASHINGTON (Reuters) - NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system, a milestone in the search for planets like the earth, the space agency said on Tuesday.

The planets, called Kepler-20e and Kepler-20f, are the smallest planets outside the solar system confirmed around a star like the Sun, NASA said in a statement.

The planets are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface.

"This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them," Francois Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said in the statement.

The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth.

Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets are in a five-planet system called Kepler-20, about 1,000 light-years away in the constellation Lyra.

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days.

Kepler-20f, at 800 degrees Fahrenheit, is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.

The Kepler space telescope detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars as planets cross in front their stars.

NASA is an acronym for National Aeronautics and Space Administration.

(Reporting by Ian Simpson; Editing by Jerry Norton)

Huge asteroid headed for close encounter with Earth

This Tuesday a huge asteroid will pass close to Earth

Source: Yahoo 7 News
Irene Klotz, Reuters
Updated November 5, 2011, 8:56 am

Giant asteroid headed Earth's way

Yahoo!7 Technology News

Close encounter

A space rock bigger than an aircraft carrier is set to get as close to the Earth as the moon in the next two days.
Strange planet blacker than coal

CAPE CANAVERAL, Fla (Reuters) - A huge asteroid will pass closer to Earth than the moon Tuesday, giving scientists a rare chance for study without having to go through the time and expense of launching a probe, officials said.

Earth's close encounter with Asteroid 2005 YU 55 will occur at 6:28 p.m. EST (2328 GMT) Tuesday, as the space rock sails about 201,000 miles from the planet.

"It is the first time since 1976 that an object of this size has passed this closely to the Earth. It gives us a great -- and rare -- chance to study a near-Earth object like this," astronomer Scott Fisher, a program director with the National Science Foundation, said Thursday during a Web chat with reporters.

The orbit and position of the asteroid, which is about 1,312 feet in diameter, is well known, added senior research scientist Don Yeomans, with NASA's Jet Propulsion Laboratory in Pasadena, California.

"There is no chance that this object will collide with the Earth or moon," Yeomans said.
Thousands of amateur and professional astronomers are expected to track YU 55's approach, which will be visible from the planet's northern hemisphere. It will be too dim to be seen with the naked eye, however, and it will be moving too fast for viewing by the Hubble Space Telescope.

"The best time to observe it would be in the early evening on November 8 from the East Coast of the United States," Yeomans said. "It is going to be very faint, even at its closest approach. You will need a decent-sized telescope to be able to actually see the object as it flies by."

Scientists suspect YU 55 has been visiting Earth for thousands of years, but because gravitational tugs from the planets occasionally tweak its path, they cannot tell for sure how long the asteroid has been in its present orbit.

"These sorts of events have been happening for most of the lifetime of the Earth, about 4.5 billion years," Fisher said.

Computer models showing the asteroid's path for the next 100 years show there is no chance it will hit Earth during that time, added Yeomans.

"We do not think that it will ever impact the Earth or moon (but) we only have its orbit calculated for the next 100 years," he said.

Previous studies show the asteroid, which is blacker than charcoal, is what is called a C-type asteroid that is likely made of carbon-based materials and some silicate rock.

More information about its composition and structure are expected from radar images and chemical studies of its light as the asteroid passes by the planet.

"I've read that we will be able to see details down to a size of about 15 feet across on the surface of the asteroid," Fisher said.

NASA is working on a mission to return soil samples from an asteroid known as 1999 RQ36 in 2020, followed by a human mission to another asteroid in the mid-2020s.

Japan also plans to launch an asteroid sample return mission in 2018.

(Corrects time element in paragraph 3)
(Editing by Tom Brown and Philip Barbara