Scientists discover Earth-like, water-rich planet.
Astronomers have discovered a new Earth-like planet that is larger than our own and may be more than half covered with water, according to a study published Wednesday in the science journal Nature. Skip related content
The so-called "super Earth" is about 42 light years away in another solar system and has a radius nearly 2.7 times larger than that of our planet, according to the study by the Harvard-Smithsonian Centre for Astrophysics.
The discovery of the planet, called GJ 1214b, represents a "major step forward" in the search for worlds similar to the Earth, added the University of California's Geoffrey Marcy in a commentary also in Nature.
The "newfound world" is too hot to sustain life as we know it, said the Harvard-Smithsonian Centre for Astrophysics in a statement.
Its density suggests however it "is composed of about three-fourths water and other ices and one fourth-rock," it said. "There are also tantalising hints that the planet has a gaseous atmosphere."
Its temperature is estimated at between 280 and 120 degrees Celsius (536 and 248 degrees Fahrenheit) with its host star about one-fifth the size of the Sun, according to the scientists.
"Despite its hot temperature, this appears to be a waterworld," says Zachory Berta, a graduate student who first spotted hints of the planet's presence.
"It is much smaller, cooler and more Earthlike than any other known exoplanet," he said in the statement.
An exoplanet is one outside of our solar system.
Berta said some of the water would likely be in crystalline form that exists at pressures greater than 20,000 times Earth's sea-level atmosphere.
Its temperature is much lower than that on the only similar discovery, called CoRoT-7b, which revolves around a star that is much hotter, the scientists say.
The CoRoT-7b has a density close to that of the Earth (5.5 grammes per cubic centimetre) and seems to be rocky, while the new discovery appears to be much less dense (1.9 g/cm3).
"To keep the planet's density that low requires that it contains large amounts of water," said Marcy. "It must contain a huge amount of water, roughly 50 percent by mass."
The "wild card" is the make-up of the gases on the planet, he said.
The planet orbits every 38 hours around a small, faint star that was first spotted by eight ground-based telescopes no larger than those used by amateur astronomers, the Harvard-Smithsonian Centre said.
Its relative closeness makes its possible to study it to determine its atmosphere.
"That will make it the first super Earth with a confirmed atmosphere -- even though that atmosphere probably won't be hospitable to life as we know it," said David Charbonneau who heads the research team.
A missile launched from a Navy ship successfully struck a dying US spy satellite passing 130 miles (210 kilometers) over the Pacific, a defense official said. Full details were not immediately available.
It happened just after 10:30 pm EST Wednesday (0330 GMT Thursday).
Two officials said the missile was launched successfully. One official, who is close to the process, said it hit the target. He said details on the results were not immediately known.
The goal in this first-of-its-kind mission for the Navy was not just to hit the satellite but to obliterate a tank aboard the spacecraft carrying 1,000 pounds (450 kilograms) of a toxic fuel called hydrazine.
US officials have said the fuel would pose a potential health hazard to humans if it landed in a populated area. Although the odds of that were small even if the Pentagon had chosen not to try to shoot down the satellite, it was determined that it was worth trying to eliminate even that small chance.
Officials said it might take a day or longer to know for sure if the toxic fuel was blown up.
Next week, the US will try to knockdown a malfunctioning spy satellite just before it crashes into earth. NASA will be putting its missile defenses to a real-life test to do this.
The US Navy Standard Missile fired from the Aegis cruiser USS Lake Erie in the northern Pacific will—for the first time—attempt to hit a satellite the size of a bus that's tumbling towards earth laden with 1,000 pounds of toxic hydrazine.
The US spy satellite never used the fuel because it failed almost as soon at it was launched 15 months ago.
"We have had no way to communicate to invoke the safety measures that are already on the bird," US Joint Chiefs of Staff Gen, James Cartwright, says.
With three quarters of the earth water, and with large parts of the land uninhabited, the chances are slim the satellite could kill anyone, yet possibilities of danger cannot be ruled out.
The problem is not so much the 5,000 lb satellite, but the 1,000 pounds of unused fuel that could cover 200 yards.
"It's hard to find areas that have any significant population to them where you could put a toxic substance down across a couple of football fields and not have somebody at risk," Administrator NASA, Michael Griffin says.
Some experts think the US may have another motive: keeping wreckage from one of its newest spy satellites out of enemy hands.
"This is the first of a new generation of radar-imaging intelligence satellites. It has advanced technology on it. They may just want to keep it off of eBay," John Pike from globalsecurity.org says.
Despite all the meticulous preparations, even if the missile misses there's no real downside.
"So there is almost nothing we can do here that makes it worse. Almost everything we can do technically makes it better, which was a very strong factor weighting the decision," Griffin says.
