Last September, astronomers confirmed the first rocky planet ever found outside our solar system, the wonderfully named CoRoT-7 b. Scientists have studied the properties of this cosmic trailblazer, and it could be among the most volcanic places in the universe.

Located some 480 lightyears from Earth, CoRoT-7 b is about five times the mass of Earth and 1.5 times the diameter. Upon its initial discovery, astronomers determined its extreme proximity to its star would create daytime temperatures of 4,000 degrees Fahrenheit and nighttime temperatures of -350 degrees Fahrenheit.

Since then, a team of astronomers at the University of Washington have determined that, unless the planet's orbit is pretty much perfectly circular, CoRoT-7 b likely experiences constant, extreme volcanic eruptions. Because the planet is only 1.6 million miles away from its star - about a sixtieth of the distance between Earth and the Sun - an orbital deviation as tiny as 155 miles would be enough to cause extreme volcanism. If there are any other planets in CoRoT-7 b's solar system, then it would almost certainly experience deviations in excess of that amount. This is because any such orbital irregularities would create tidal forces, but not like anything seen on Earth.

Washington postdoctoral research Rory Barnes explains:

CoRoT-7 b most certainly has no oceans. A planet on a non-circular orbit experiences different amounts of gravitational force at different points along the orbit, feeling the strongest gravitational pull when it is closest to the star and the weakest when it is most distant. As the planet moves between these two points, it stretches and relaxes. This flexing produces friction that heats the interior of the planet resulting in volcanism on the surface.


Similar processes have shaped Jupiter's moon Io, which is the most geologically active place in our solar system. However, because CoRoT-7 b is so much hotter than Io, the effects would likely be far more extreme, creating volcanism on a far greater order of magnitude. As such, it probably comes as no surprise to say that, even though CoRoT-7 b brought the search for rocky exoplanets to an end, those search for life on other planets should probably look elsewhere.

[Astrobiology Magazine]