Image: NASA’s Kepler mission has discovered a new planetary system that is home to the smallest planet yet found around a star like our sun, approximately 210 light-years away in the constellation Lyra. The line-up above compares artist’s concepts of the planets in the Kepler-37 system to the moon and planets in the Solar System. The smallest planet, Kepler-37b, is slightly larger than our moon, measuring about one-third the size of Earth. Kepler-37c, the second planet, is slightly smaller than Venus, measuring almost three-quarters the size of Earth. Kepler-37d, the third planet, is twice the size of Earth. Credit: NASA/Ames/JPL-Caltech.

Small Planets Confirm Kepler’s Capabilities


The planetary system around Kepler-37, some 210 light years from Earth in the constellation Lyra, had its place in the media spotlight yesterday, although it will surely be a brief one. But it’s heartening to see the quickening interest in exoplanets that each new discovery brings. Will the interest continue? In the Apollo days, public enthusiasm reached a frenzy as we moved toward the first lunar landings, then plummeted. What the media see as the big event in exoplanetary science is the discovery of a terrestrial world around a star like the Sun. Let’s hope there is no similar letdown afterwards.

After all, we’re getting close, and discoveries like those announced yesterday remind us that Kepler can find very small worlds indeed. Kepler-37b lays claim to being the smallest planet yet found around a star similar to the Sun, similar in this case meaning a G-class star with a radius about three-quarter’s of the Sun’s. The new planet is just a bit larger than our Moon, as the image below shows. The world is assumed to be rocky and, with a 13-day orbit, its surface temperature is probably in the range of 700 K.

Read more: Small Planets Confirm Kepler’s Capabilities — Centauri Dreams.

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