Astronomers said on Thursday they had found six planets orbiting a distant star in the most exciting but also most challenging find since exploration of other solar systems began 15 years ago. None of the so-called exoplanets, orbiting the star Kepler-11 2,000 light years away, is remotely comparable to the Earth, but the detection of them is a major technical feat, the scientists said.
Five planets are relatively small, ranging in mass from 2.3 to 13.5 times that of Earth, but orbit Kepler-11 at blistering proximity, encircling it at a distance that is even closer than Mercury to the Sun. Their "year" - the time it takes to encircle the Sun - is less than 50 days. A sixth exoplanet is large and farther out, with an orbital period of 118 days, and is of a yet-to-be determined mass, although it is likely to be a "gas giant" like the outer planets of our own Solar System. Reporting their find in the British journal Nature, the astronomers said the star system was mind-boggling because the planets were so small, so numerous and yet so densely packed.