Earthlike Exoplanets May be More Common Than We Thought

A recent survey found that Earthlike planets are more common around red dwarf stars. And there are lots of those nearby.

Stars come in all physical sizes, of course, ranging from tiny black holes and white dwarfs to supergiants and even bigger hypergiants (just to be clear: black holes are physically smaller-than-our-own-moon small bodies, but are fantastically dense, with matter so massive that a teaspoon full would plummet right through to the center of the Earth). Stars are made of all manner of things, from common hydrogen like our sun to exotic stars that burn carbon and beryllium.

Red dwarfs are stars that are cooler than our own sun. They’re much smaller, about a third of the sun’s size, and dimmer. And they are fairly common in our corner of the Milky Way galaxy. In fact, most or our neighboring stars are red dwarfs.

A planet orbiting a red dwarf can orbit much more closely without getting burned up. The Earth sits right in the middle of our Goldilocks Zone, where water neither boils away nor freezes solid, and it takes us 365.25 days to make one orbit. Red dwarf planets can have an orbit as short as just 20 days. Imagine, a three week long year. “Honey, didn’t we just celebrate New Year’s last month?”

Here’s where it gets interesting: scientists belonging to the Harvard/Smithsonian Center for Astrophysics carefully examined 64 nearby stars targeted by Kepler. They found no less than 95 planets orbiting those stars, and, of those 95, they found three planets of interest. That’s a ratio of 1 potential Earthlike planet for every 32 planets discovered – an astonishingly high ratio of potential earths out there.

The planets discovered range in size from 90% of Earth’s size up to 170%, and all of them are in the Goldilocks zone of their red dwarf hosts. Now, sit down before you read the next paragraph.

These most recent discovered planets of interest are only 300 to 600 light years away. That’s still a heartbreakingly long way away, but it’s just a ninth of the distance to Kepler-64F, the other most recent Goldilocks Zone planet discovery.

The net result of this discovery is that the likelihood of discovering an Earthlike star in our own stellar neighborhood is dramatically higher than we once thought.

You can read more about this most interesting discovery at NASA.gov/Kepler.

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