Earth-like planet discovered

Nasa recently discovered a new planet outside Earth’s solar system that is eerily similar to Earth in many  important aspects. Scientists say the temperature on the surface of the planet, named Kepler 22b is around 22 Celsius, which is similar to a warm spring day in the UK It could also have continents, oceans and may contain life.

Kepler 22b is about twice the size of Earth, is 600 light years away and was found in the middle of the habitable zone, making it the best potential target for life. It is the first so-called “super-Earth” known to lie within the “habitable” zone of a Sun-like star. That is the orbital band where temperatures are just right to allow the existence of surface liquid water. This means the planet could have continents and oceans just like the Earth. And where there is liquid water, there could also be life. Scientists believe Kepler-22b may not only be habitable, but possibly even inhabited.

The discovery announced recently was made by Nasa’s Kepler planet-hunting telescope. This is the first time Kepler confirmed a planet outside Earth’s solar system in the habitable  zone. Recently Two other small planets have also been discovered orbiting stars which were smaller and cooler than the Sun. But both are at the very edges of their habitable zones and neither was as promising, as Their orbits more closely resemble those of Mars and Venus.

“This discovery supports the growing belief that we live in a universe crowded with life,” said Dr Alan Boss, from the Carnegie Institution in Washington DC, who helped identify the planet from data obtained by the Kepler space telescope. The telescope, launched by the American space agency Nasa, is watching 155,000 stars looking for tiny dimmings in brightness that betray the presence of planets.

Kepler-22b’s host star could almost be a twin of Earth’s sun. It lies in the region of the constellations of Lyra and Cygnus, is slightly smaller than the Sun and about 25% less luminous. The planet orbits the star in 290 days, compared with the Earth’s 365, at a distance 15% closer than the Earth is from the Sun. This means that Kepler 22b lies right in the centre of the star’s habitable zone, where potentially perfect conditions exist for life.

The planet was spotted after making a “transit” across the front of its parent star, causing the star’s brightness to dip. At least three transits are needed before such a signal can be confirmed as a planet. Dr Douglas Hudgins, Kepler programme scientist at Nasa headquarters in Washington, said: “This is a major milestone on the road to finding Earth’s twin.” and a report on the discovery is due to be published by the Astrophysical Journal.