Astronomers said Wednesday that space is littered with hundreds of billions of planets that have been ejected from the planetary systems that gave them birth and either are going their own lonely ways or are only distantly bound to stars at least as 10 times as far away as the Sun is from the Earth.
There are two Jupiter-mass planets for each of the 200 billion stars in the Milky Way galaxy, according to measurements and calculations undertaken by an international group of astronomers led by Takahiro Sumi, of Osaka University in Japan, and reported in the journal Nature. …
Planetary astronomers said the results would allow them to tap into a whole new unsuspected realm of exoplanets — as planets outside our own solar system are called — causing scientists to re-evaluate how many there are, where they are and how they are created, even as astronomers immediately began to ponder whether the new planets in question are in fact floating free or just far from their stars, at distances comparable to those of Uranus and Neptune in our own solar system. …
More and better observations should eventually establish whether they are true orphans or just on a long leash.
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