What Is Planet Kepler-10b Like?

Kepler-10b as a scorched world, orbiting at a distance that’s more than 20 times closer to its star than Mercury is to our own Sun. The daytime temperature’s expected to be more than 2,500 degrees Fahrenheit, hotter than lava flows here on Earth. Intense radiation from the star has kept the planet from holding onto an atmosphere, but the animation shows flecks of silicates and iron that have boiled off a molten surface and are swept away by the stellar radiation, much like a comet’s tail when its orbit brings it close to the Sun. Many years ago, before Kepler, our team built a robotic telescope at Lick Observatory to learn to do transit photometry. We called it the “Vulcan Telescope,” named after the hypothetical planet that scientists in the 1800’s thought might exist between the Sun and Mercury. A planet that might explain the small deviations in Mercury’s orbit that were later explained with Einstein’s theory of general relativity. Vulcan is the god of fire in Roman mythology, a name befitting of a world so close to the Sun. When I saw the artist’s rendering of Kepler-10b for the first time, the thought that immediately came to my mind was that this is our planet Vulcan. We’d come full circle in our quest and we know that we’ve only begun to imagine the possibilities.