The Kepler Space Telescope mission has encountered a tiny planetary system orbiting a star much like our Sun. Located in a system dubbed Kepler-37, which is located in the Constellation Lyra and is about 210 light-years away from Earth, the small world of Kepler-37b is smaller than our Moon.
Finding this world was not easy; it is smaller than the planet Mercury, the tiniest planet in our solar system.
“Even Kepler can only detect such a tiny world around the brightest stars it observes,” said Jack Lissauer, a planetary scientist at NASA’s Ames Research Center. “The fact we’ve discovered tiny Kepler-37b suggests such little planets are common, and more planetary wonders await as we continue to gather and analyze additional data.”
Kepler-37b has two companion planets and resides in the so-called “habitable zone,” the area within a solar system where water can reside as a liquid on the planet’s surface. Unfortunately, while Kepler-37 might be like our star, the solar system there bears little resemblance to our own. Due to its size, astronomers doubt that Kepler-37b has an atmosphere and therefore it cannot support life as we know it. Another nearby world, Kepler-37C, is slightly smaller than Earth (researchers have estimated it is about three-quarters the size of our home world). While another, Kepler-37d, is twice the size of Earth. All of these planets are more than likely terrestrial (rocky) worlds. All of the worlds discovered circling Kepler-37 orbit closer than the planet Mercury does around our Sun. (Mercury is an average distance of about 36 million miles away from the Sun). This suggests that these are extremely hot, barren worlds. Kepler-37b orbits every 13 days, Kepler-37c every 21, and Kepler-37d every 40. Estimates of the temperature on Kepler-37b place it at a scalding 800 degrees Fahrenheit (700 Kelvin).
While this recent discovery might not sound too encouraging, it actually points to a dramatic refinement over what was discovered previously. In the early days of exoplanet discovery, the worlds found were massive gas giants dubbed “Super Jupiters.” Many of these orbit close to their parent stars and suggest solar systems that are devoid of worlds that could support life.
“We uncovered a planet smaller than any in our solar system orbiting one of the few stars that is both bright and quiet, where signal detection was possible,” said Thomas Barclay, Kepler scientist at the Bay Area Environmental Research Institute. “This discovery shows close-in planets can be smaller, as well as much larger, than planets orbiting our Sun.”