Space Observers Measure the Length of Day for Exoplanet 63 Light Years from Earth

Earth spins at 1,000 miles per hour and comprises a 24-hour day. Jupiter spins at 29,000 miles per hour, the fastest in our solar system, and has only ten-hour days. Beta Pictoris b., a nearby exoplanet, spins even faster than Jupiter.

For the first time ever, astronomers measured the length of a day on a planet outside of our solar system. Beta Pictoris b. rotates at 56,000 miles per hour and its days only last eight hours. Of the 1,800 exoplanets discovered beyond our solar system, astronomers chose Beta Pictoris b. for a few reasons.

It is one of the better understood exoplanets in terms of size, temperature, atmosphere, and now rotation. Beta Pictoris b. is one of only a dozen exoplanets that has been directly observed by scientists. Others are discovered/examined using indirect detection methods. The astronomers' article, "Fast spin of the young extrasolar planet β Pictoris b," was published today in the journal Nature.

Through the use of the Cryogenic High-Resolution Infrared Echelle Spectrograph  (CRIRES) instrument on the European Southern Observatory's Very Large Telescope in Chile, Dutch astronomers were able to document the findings on Beta Pictoris b on December 17, 2013 - five years after the planet's discovery.

"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," said Remco de Kok, one of the paper's co-authors, according to NBC News.

The exoplanet is 3,000 times more massive than Earth, seven times more massive than Jupiter, and is only 20 million years old. It is also eight times farther from its host star than Earth is from the sun. Its mass helps support the scientific notion that a planet's rotational velocity is closely related to its size - the bigger the mass, the faster the velocity.

The next goal for the astronomers is to make a global map of Beta Pictoris b. with cloud patterns and storms to essentially track the behavior of a planet outside of our solar system, through the use of the European Extremely Large Telescope. The exoplanet is an easy target for astronomers because its shines brightly, which will be helpful moving forward.

You can read more about Beta Pictoris b. in the complete published paper on the ESO website.