An international team of astronomers has discovered an exoplanet--one outside our solar system--that has a more Earthlike orbit than any alien planet discovered so far using the same technique.
The planet, called CoRot-9b, was discovered by the French-operated satellite
CoRot, which has been in orbit since 2006. The spacecraft detected
CoRot-9b by measuring the dimming of its star's brightness as the planet
passed in front of it, a technique called "transit observation." The
small dip in brightness allows the planet's size to be calculated. By
measuring the amount of time it takes the planet to complete its orbit,
researchers can determine the planet's distance from its star.
The planet travels around its star every 95 Earth days, at a distance
about half of that between Earth and the sun. This distance is still 10
times farther than any other planet discovered using this method. Its
surface temperature is between -23 and 157 °C and, while its atmosphere
could contain liquid water, CoRot-9b is made mostly of hydrogen and
helium and therefore is unlikely to support life.
"This is the first time that we can probe the atmosphere of such a
cool planet outside the solar system," says Jason Wright, an assistant
professor of astronomy at Pennsylvania State University, who was not
involved in the discovery. Wright says that the finding is an important
step forward in finding an Earthlike planet that could support life, one
of the biggest goals in astronomy.