The galaxy is getting very crowded. There may be 300 billion stars in the Milky Way, but until just over 20 years ago, we knew of only one of them that was orbited by planets. In the years since, the galactic census has exploded, with more than 4,700 confirmed or candidate planets discovered so far and astronomers concluding that every star in the galaxy is parent to at least one world.
What has always been harder to spot are Earthlike planets — relatively small ones with a rocky surface, orbiting their sun at the not-too-close, not-too-far distance that would allow liquid water to exist. Today, however, that changed in a big way, as NASA announced that a single star relatively close to Earth is home to no fewer than seven Earthlike planets. If you’re looking for extraterrestrial life, there may be no place better.
The new findings, published in the current issue of Nature, are the result of more than six years of study of the small star Trappist-1, located just over 39 light years from Earth — barely one town over in a galaxy that measures 100,000 light years across. The star got its name from a rough acronym of the telescope in the Chilean desert that has studied it the most: the Transiting Planets and Planetesimals Small Telescope. As the name suggests, the Trappist telescope looks for planets by watching for the portion of their orbit in which they transit — or pass in front of — their star, causing a tiny but regular dimming in starlight.
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