Researchers have confirmed the existence of the smallest known exoplanet. Kepler-37b is smaller than Mercury, and marginally larger than Earth’s moon. The Kepler team at Ames Research Center explains:
The planets are located in a system called Kepler-37, about 210 light-years from Earth in the constellation Lyra. The smallest planet, Kepler-37b, is slightly larger than our moon, measuring about one-third the size of Earth. It is smaller than Mercury, which made its detection a challenge.
The moon-size planet and its two companion planets were found by scientists with NASA’s Kepler mission to find Earth-sized planets in or near the “habitable zone,” the region in a planetary system where liquid water might exist on the surface of an orbiting planet. However, while the star in Kepler-37 may be similar to our sun, the system appears quite unlike the solar system in which we live.
Astronomers think Kepler-37b does not have an atmosphere and cannot support life as we know it. The tiny planet almost certainly is rocky in composition ….
…. Kepler-37’s host star belongs to the same class as our sun, although it is slightly cooler and smaller. All three planets orbit the star at less than the distance Mercury is to the sun, suggesting they are very hot, inhospitable worlds. Kepler-37b orbits every 13 days at less than one-third Mercury’s distance from the sun. The estimated surface temperature of this smoldering planet, at more than 800 degrees Fahrenheit (700 degrees Kelvin), would be hot enough to melt the zinc in a penny. Kepler-37c and Kepler-37d, orbit every 21 days and 40 days, respectively.
The Kepler mission is pretty cool. Since its launch in 2009, the spacecraft has identified 2,740 planet candidates, 114 of which have been confirmed. Additionally, Kepler has identified 2,165 eclipsing binary stars. There is a tremendous amount of data, and the mission team keeps a running list of Kepler discoveries.