Scientist have for the first time measured the rotation of an extrasolar planet to determine the length of its days.

Beta Pictoris b orbits a star around 63 light years from Earth and has a mass 3000 times greater and measures 16 times larger than our home planet. However, a day on Beta Pictoris only lasts eight hours, with the gassy giant spinning at around 90,000km/h, notably quicker than the Earth which rotates at a mere 1,675 km/hour.

Study co-author Remco de Kok said:

“It is not known why some planets spin fast and others more slowly, but this first measurement of an exoplanet’s rotation shows that the trend seen in the Solar System, where the more massive planets spin faster, also holds true for exoplanets. This must be some universal consequence of the way planets form.”

The researchers measured the rotation using the CRIRES instrument of the European Southern Observatory’s Very Large Telescope (VLT) and a technique called high-dispersion spectroscopy, where they analyse the changes in the wavelengths of radiation emitted and the principle of the Doppler effect to determine its rotational velocity.

Their findings are published in the journal Nature.