Smallest Planet outside our solar system discovered!

The newly found planet is the smallest yet discovered, it is also the first ever to be confirmed as being a rocky planet.  The object is 40% bigger than earth (in diameter), and is called Kepler-40b. It was discovered by NASA's Kepler spacecraft.

The planet is quite hot, and thought to be partially molten.  No liquid water or life is likely to exist on the planet.  The discovery is still significant though, as it shows that Kepler is capable of finding  rocky planets, including the kind that may be more suitable to life.
Before Kepler-40b was discovered, all extrasolar planets were either gas giants, or planets which composition could not be confirmed.  There are other planets that are thought to be rocky, but not enough evidence exists on these bodies to confirm it.

The planet was first suspected of existing a few months after Kepler's launch in 2009.  Kepler detected a drop in light of 0.0152% periodically from a star dubbed Kepler-10.  The periodic lower light level suggested a planet slightly larger than earth orbiting the planet once every 20 hours.  To confirm their findings and the mass of the object, they used the Keck I telescope in Hawaii to study the planet further.  This telescope determined that the parent star (Kepler-10) was 565 light years from earth, and that it did have a planet about the same size of earth orbiting it.

The team then studied the star and planet even more closely, watching it at 1 minute intervals to determine what the parent stars age, mass, and size.  Through this information, the team determined the information they know about the planet. Kepler-40B has a mass 4.56 the earth's, and a diameter 1.4 times larger than earth's.  This suggests that the planet is made mostly of metals. The planet is estimated to have a temperature reaching 1,500 C, almost reaching the melting point of iron.

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