NASA scientists have broken the record for the smallest planet beyond our solar system! The newly-found planet, Kepler 37b, is rocky and only slightly larger than our moon at a mere 3865 kilometers in diameter. It is hellishly hot—it’s so close to its host star that it has a 13-day orbit. This planet may be tiny, but it’s making a big splash in the realms of science!


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Kepler 37b’s host star, Kepler 37, is one of about 150,000 stars being watched by the space-based Kepler Observatory every minute of every day. The mission was launched in 2009 to look for Earth-sized planets positioned in “habitable zones” where liquid water, believed to be necessary for life, can exist on their surfaces. In the beginning, the Kepler team could only find large planets similar in size to Jupiter and Neptune. However, the recent success in finding small planets like Kepler 37b is indicative of amazing technological achievements.

This discovery is important in the search for habitable worlds because it demonstrates that the Kepler telescope is sensitive enough to find Earth-sized planets with longer orbits. Kepler 37b has also allowed scientists to study the architecture of other star systems at the low range for the first time, and revolutionized astronomers' notions of our galaxy as a place that must be teeming with rocky planets.

Even with all of the state-of-the-art technology used at the Kepler Observatory, finding a planet is tricky. If a planet orbits a star, and the orbit of the planet aligns just right, we can see the light from the star dim slightly as the planet passes directly in front of the star. The real trick though, is figuring out the size of the planet.

NASA currently uses a process called asteroseismology to figure out how big a star is. However, the discovery of asteroseismology was not funded by NASA—it was funded by the public! A nonprofit called White Dwarf started the Pale Blue Dot project to raise money for research. They let people “adopt” a Kepler star for a $10 donation and used that money to help researchers. They ended up raising tens of thousands of dollars that funded the asteroseismology used to measure Kepler-37b. This just goes to show, when you put the power of cooperation behind the power of science, you get record-breaking results!

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