Astronomers find sub-Neptune GJ 3090 b orbiting its red dwarf backward

A team led by the University of Geneva has found the first exoplanet orbiting opposite to its red dwarf host star, GJ 3090, 73 light-years away. The sub-Neptune GJ 3090 b is 2.2 times Earth's width and 4.5 times its mass, with a 2.9-day orbit and an obliquity of about 136 degrees.

• GJ 3090 b is 2.2 times Earth's width and 4.5 times its mass
• It orbits its red dwarf every 2.9 days
• Orbital obliquity of about 136 degrees means retrograde motion
• Smallest exoplanet with a mapped obliquity around an M dwarf