Astronomers find planet GJ 3090 b orbiting its star backwards

An international team using the NIRPS spectrograph measured the 3D orbit of Neptune-sized GJ 3090 b around an M dwarf, finding an obliquity of about 136 degrees — the planet orbits backwards. It is the first known retrograde exoplanet around this type of star; researchers found no massive companion that could explain the tilt.

• GJ 3090 b's orbital obliquity is about 136 degrees, opposite the star's spin
• First retrograde exoplanet around an M dwarf measured in 3D
• No massive companion found that could explain the extreme tilt
• Measurement made with the NIRPS near-infrared spectrograph