International Group of Astronomers discovered asteroid (130) Elektra has three satellites at once. This makes Electra the first quadruple asteroid system ever discovered, the researchers say.
The asteroid itself with a diameter of about 260 km was discovered in the 19th century. It rotates in the main belt – a region of the solar system located between the orbits of Mars and Jupiter, where many asteroids and small planets have accumulated.
Moons around asteroids were also discovered not for the first time. Scientists know more than 1.1 million asteroids, and more than 150 of them have at least one moon. Such satellites are difficult to detect due to their small size and low illumination.
The first moon of Electra, designated S/2003 (130) 1, was discovered in 2003. It has a diameter of only 6 kilometers and revolves around Electra at an average distance of about 1300 kilometers.
In 2014, astronomers noticed a second satellite, S/2014 (130) 1. Its diameter is only 2 km, and the average orbital distance is 500 km.
The third moon discovered in a recent study is called S/2014 (130) 2. It is even smaller and orbits even closer: only 1.6 km across, with an orbital distance of 340 km.
To find it, the team used archived data from the SPHERE instrument attached to the European Southern Observatory’s Very Large Telescope and ran it through special software and additional algorithms to weed out visual noise. Once the computers finished processing, a third moon was clearly visible next to Elektra.
The new method for detecting small space objects can be used in future research.