Beta Pictoris b, measured the rotation rate of the exoplanet

Artist’s impression of the planet Beta Pictoris b. Credit: ESO

Observations from ESO’s Very Large Telescope (VLT) have, for the first time, determined the rotation rate of an exoplanet. Beta Pictoris b has been found to have a day that lasts only eight hours. This is much quicker than any planet in the Solar System, its equator is moving at almost 100.000 kilometres per hour. This new result extends the relation between mass and rotation seen in the Solar System to exoplanets. Similar techniques will allow astronomers to map exoplanets in detail in the future with the European Extremely Large Telescope (E-ELT).

More at ESO: Length of Exoplanet Day Measured for First Time

arXiv: The fast spin-rotation of a young extrasolar planet