Saturday, August 13, 2011

Darkest Planet Found - Planet TrES-2b

Planet TrES-2b (photo by National Geographic.)
The NASA guys are really doing their job, it seems.. With NASA's Kepler space telescope, astronomers have discovered in our home galaxy, a planet blacker than coal. It's about the size of Jupiter.
Orbiting only about three million miles out from its star, the gas giant planet, dubbed TrES-2b, is heated to 1,800 degrees Fahrenheit (980 degrees Celsius). Yet the apparently inky world appears to reflect almost none of the starlight that shines on it, according to a new study.

The Earth-orbiting Kepler spacecraft was specifically designed to find planets outside our solar system. But at such distances—TrES-2b, for instance, is 750 light-years from us—it's not as simple as snapping pictures of alien worlds.
Instead, Kepler—using light sensors called photometers that continuously monitor tens of thousands of stars—looks for the regular dimming of stars.
Such dips in stellar brightness may indicate that a planet is transiting, or passing in front of a star, relative to Earth, blocking some of the star's light—in the case of the coal-black planet, blocking surprisingly little of that light.

When a planet passes in front of its star, the world's shaded side faces Kepler. But as the planet begins orbiting to the side of and "behind" its star, its star-facing side comes to face the viewer. The amount of starlight grows until the planet, becoming invisible to Kepler, passes fully in back of its star.
Watching TrES-2b and its star, Kepler detected only the slightest such dimming and brightening, though enough to ascertain that a Jupiter-size gas giant was the cause.
The light reflected by the newfound extrasolar planet, or exoplanet, changed by only about 6.5 parts per million, relative to the brightness of the host star.

Current computer models predict that hot-Jupiter planets—gas giants that orbit very close to their stars—could be only as dark as Mercury, which reflects about 10 percent of the sunlight that hits it.
TrES-2b is so dark that it reflects only one percent of the starlight that strikes it, suggesting that the current models may need tweaking.
.... text taken from National Geographic National News.

So much so...
Have a nice Saturday..

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