A star already known to host five alien planets may actually be home to a whopping nine full-fledged worlds - a planetary arrangement that, if confirmed, would outnumber our own solar system and set a new record for the most populated system of extrasolar planets yet found.
The sun-like star, called HD 10180, is located approximately 127 light-years away from Earth. In a previous study that was published in August 2010, astronomers identified five confirmed alien worlds and two planetary candidates.
Now a new study confirms both previous candidates in the HD 10180 system, and also suggests that two more planets could be orbiting the star. This could bring the tally up to nine planets, said lead author Mikko Tuomi, an astronomer at the University of Hertfordshire in the U.K. Our solar system, by comparison, has eight official planets (with Mercury closest to the sun and Neptune at the farthest end). Pluto and several other smaller objects are considered dwarf planets, not full-blown worlds.
"The data indicates that there are not only seven but likely as many as nine planets in the system," Tuomi told SPACE.com in an email interview. "The two new planets appear to have orbital periods of roughly 10 and 68 days and masses of 1.9 and 5.1 times that of Earth, which enables the classification of them as hot super-Earths, i.e. planets with likely scorchingly hot rocky surfaces."