Extrasolar planet news
A newly discovered extrasolar planet is the closest thing to an Earth-like planet that’s yet been discovered; although there are some major differences from Earth, it’s likely the smallest extrasolar planet found to date orbiting a normal star, and it’s probably rocky like Earth. The planet has about 5 1/2 times the mass of Earth, a good bit smaller than the previous smallest planet which was 7 1/2 times Earth-size. Astronomers have found Earth-sized planets, but they were orbiting neutron stars. The new planet is 2 1/2 times as far from its star as the Earth is from the sun (interesting because previous smaller planets have been much closer to their stars) and its star is a red dwarf, considerably cooler than the sun, and so this planet is too cold for liquid water and likely too cold for life as we know it. But still, it’s a good step on the way to finding an Earth-like planet. And the way it was found is interesting. Most of the extrasolar planets discovered to date have been identified because of minuscule shifts in the position of their parent stars due to the tiny but measurable gravitational pull of the planets; this one was found by using gravitational microlensing, in which the parent star’s gravity bends the light from a distant background star. The planet causes a brief brightening in the light from the background star.
http://www.space.com/scienceastronomy/060125_smallest_planet.html
