The planet that grew a second atmosphere

Gliese 1132 b is similar to Earth in a striking number of ways. Its radius is only slightly larger, as is its mass. Even its age – 4.5 billion years old – is similar to that of our planet. But this world does have one striking difference: it orbits much closer to its red dwarf parent star, completing an orbit in just 1.6 Earth days. This proximity results in Gliese 1132 b experiencing a much higher surface temperature than our planet, at 256 degrees Celsius (493 degrees Fahrenheit), with the intense radiation stripping the atmosphere.

But astronomers have recently discovered that something extraordinary is happening on Gliese 1132 b. The gravitational influence of its host star creates intense tidal forces that squeeze and stretch the planet. This ‘flexing’ gives rise to violent volcanic activity and causes gases to rush to the world’s surface.

These gases are building the world a second atmosphere. While this is exciting in itself, being the first time astronomers have ever spotted anything like this, the ‘regrown’ atmosphere, due to its origin, also provides astrogeologists with a unique opportunity to study the interior chemical composition of an exoplanet by proxy.