Mercury rotates nine seconds faster than scientists had thought, probably because of gravitational effects from Jupiter.

A team led by Alexander Stark of the German Aerospace Center in Berlin studied three years of data from NASA's MESSENGER spacecraft, which orbited the planet between 2011 and 2015 and measured Mercury's rotations more precisely than ever before.

The data also confirm that the planet has a molten outer core, causing this part to rotate at a different speed from the solid inner layers.

Geophys. Res. Lett. http://doi.org/7mc (2015)