# Discovery of exoplanet GJ 3090 b retrograde orbit

> Live situation record from CLSTR: https://clstr.news/situations/discovery-of-exoplanet-gj-3090-b-retrograde-orbit
> Updated: 2026-09-24T11:51:00.000Z. Sources: 6. Developments: 2.

Astronomers led by the University of Geneva have identified an unusual exoplanet, GJ 3090 b, which possesses a retrograde orbit. Located approximately 54 to 73 light-years from Earth in the Virgo constellation, the sub-Neptune planet orbits its red dwarf host star in a direction largely opposite to the star’s rotation.

Using the NIRPS spectrograph at the La Silla Observatory, researchers measured a three-dimensional spin-orbit angle of approximately 136 degrees. This discovery marks the first known retrograde planet identified around an M dwarf star. Because no massive nearby objects or stellar companions were found to explain the misalignment, researchers suggest the planet may have formed in a second, backward-rotating disk of gas, a finding that challenges standard theoretical models of planetary formation.

## Claims

- The measurement of the psi angle provides clues about the formation and evolution of planetary systems. (corroborated by 2 sources)
- The three-dimensional spin-orbit angle of GJ 3090 b is approximately 136 degrees. (corroborated by 2 sources)
- The study was conducted using the NIRPS spectrograph at the La Silla Observatory. (corroborated by 2 sources)
- The exoplanet GJ 3090 b follows a strongly misaligned retrograde orbit around its red dwarf host star. (single source)
- GJ 3090 b has a radius approximately 2.18 times that of Earth. (single source)
- The mass of GJ 3090 b is roughly 4.52 times greater than Earth's. (single source)
- GJ 3090 b is the first known retrograde planet discovered around an M dwarf star. (single source)
- The planet is located approximately 73 light-years away. (single source)

## Timeline

### 2026-09-24: Exoplanet GJ 3090 b discovered in unusual retrograde orbit

Astronomers have discovered GJ 3090 b, a sub-Neptune exoplanet orbiting its red dwarf star in a retrograde direction, challenging standard planetary formation theories.

4 sources. https://clstr.news/cluster/exoplanet-gj-3090-b-discovered-in-unusual-retrograde-orbit

### 2026-09-21: Exoplanet GJ 3090 b confirmed to have a retrograde orbit

Astronomers have confirmed that exoplanet GJ 3090 b has a retrograde orbit, spinning in the opposite direction of its host star, challenging existing models of planetary formation.

2 sources. https://clstr.news/cluster/exoplanet-gj-3090-b-confirmed-to-have-a-retrograde-orbit

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Cite as: Discovery of exoplanet GJ 3090 b retrograde orbit. CLSTR, https://clstr.news/situations/discovery-of-exoplanet-gj-3090-b-retrograde-orbit