Earth-Like Worlds May Be Plentiful

A new study suggests planets similar to Earth may be common in the Milky Way.  Basing their conclusions on data obtained by NASA's Kepler planet-hunting spacecraft, scientists are seeing that whereas gas giant planets like Jupiter seem to form only around metal-rich stars, small, rocky worlds like Earth can form around a broader range of stars.  Thus, they could be all over the galaxy.

There's also a time factor in this work.  Metals-- in astronomers' terms, everything other than hydrogen and helium-- were formed in the bellies of huge stars.  When those stars went supernova, the metals were thrown out across the universe to become part of subsequent stars, planets, people, etc.  That suggests planets like Jupiter didn't exist in the early universe, but worlds like Earth could be ancient.

That has clear implications for the possibility of life in the galaxy.  It also suggests that if and when humanity masters interstellar travel, there will be familiar places to go.  It could also suggest, however, that no race has yet mastered such travel, even after possibly billions of years, as we have no evidence for the existence of such a glorious civilization stretching across the Milky Way.