Smallest Exoplanet Directly Observed a Mere 300 Light-Years Away

While NASA's Kepler spacecraft usually grabs all the planet-hunting headlines, today it's the European Space Observatory's (ESO) Very Large Telescope. The ESO is reporting that it has directly observed the smallest planet outside of solar system, a mere 300 light-years away from us.

Thousands of exoplanets have been documented, but very few are directly observed. Instead, most are discovered by watching for signs that they exist in the environment around them - such as the change in a star's brightness as the planet passes between it and Earth.  

"Direct imaging of planets is an extremely challenging technique that requires the most advanced instruments, whether ground-based or in space," says Julien Rameau from the Institut de Planetologie et d'Astrophysique in Grenoble, France. "Only a few planets have been directly observed so far, making every single discovery an important milestone on the road to understanding giant planets and how they form."

The planet, dubbed HD 95086 b, is faint and small by cosmic standards, but still puts our solar system's giants to shame. By comparison, HD 95086 b is four to five times larger than our system's largest planet, Jupiter. The surface temperature of the newly-discovered planet is believed to be around 1,300 degrees Fahrenheit. 

The exoplanet's parent star, HD 95086, is a relatively young star similar to our sun in size. It's age is estimated between 10 and 17 million years, and  HD 95086 is surrounded by a rocky field of debris, much like the sun. It's from this disc of gas and other planet-building materials that the planet was probably formed.

"Its current location raises questions about its formation process. It either grew by assembling the rocks that form the solid core and then slowly accumulated gas from the environment to form the heavy atmosphere, or started forming from a gaseous clump that arose from gravitational instabilities in the disc," team member Anne-Marie Lagrange explained. "Interactions between the planet and the disc itself or with other planets may have also moved the planet from where it was born."

You can read the full published study detailing the findings in the journal The Astrophysical Letters.