A rocky planet about the size of Earth discovered orbiting a star outside our solar system has been hailed as a "significant step" in the search for habitable worlds similar to our own.
Kepler-10b, which was found by Nasa's Kepler space telescope, has an estimated temperature of more than 1,370C (2,500F), which is hot enough to melt iron.
But even though it is far too close to its sun for life to survive, the discovery of the smallest planet to be detected outside our solar system was nevertheless described by scientists as a major breakthrough.
The planet, which is about 1.4 times the size of Earth and completes a full orbit of its Sun once a day, could represent another step in the search for other habitable planets, scientists claimed.
Douglas Hudgins, Kepler programme scientist at Nasa, said: "The discovery of Kepler 10-b is a significant milestone in the search for planets similar to our own.
"Although this planet is not in the habitable zone, the exciting find showcases the kinds of discoveries made possible by the mission and the promise of many more to come."
Natalie Batalha, a professor at San Jose State University and member of NASA's Kepler Mission, said that there is evidence of another potential planet in the same star system, but little is yet known about it.
She said: "There is actually already a very compelling signature of another potential planet in this system.
"There is a transit event that recurs once every 45 days and is suggestive of a planet a bit larger than two times the radius of the Earth."
The findings were described in the Astrophysical Journal.