That is the question raised by the discovery of some of the building blocks of life on one of the closest known planets orbiting a star other than our own Sun.
Astronomers have detected water and carbon dioxide -key signs of life - in the atmosphere of HD 189733b, which orbits a star 63 light years away from Earth in the constellation Vulpecula.
The planet is one of about 300 "exoplanets" that have now been detected beyond our own solar system since the first was identified in 1995. Scientists believe it could only be a matter of time before they find one similar in size and composition to Earth. Although they are excited about their ability to detect biologically important molecules so far away in space, they are more sanguine about the prospects of life on a planet that is known only by its code name.
HD 189733b is believed to be a "gas giant" planet similar in size to Jupiter and, as such, is thought to be a hostile environment for life. Its close orbit around its sun is not conducive to living organisms, which are unlikely to survive the temperatures.
But astronomers believe the techniques that revealed the presence of water and carbon dioxide on such a distant planet will soon lead them to discovering the signs of extraterrestrial life on a more Earth-like planet where living organisms can thrive.
