Astronomers find a planet orbiting its star backwards, and nobody knows how it got that way

Astronomers have discovered GJ 3090 b, a Neptune-sized planet orbiting its star in the opposite direction to the star’s rotation, an unusual configuration whose origin remains unexplained.

AOL reports that GJ 3090 b has an orbital tilt of about 136 degrees, confirming that the planet travels backward relative to its star. The research was led by scientists at Queen Mary University of London.

Planets typically form from the same rotating disks of gas and dust as their stars and therefore orbit in the same direction. Researchers initially suspected that another massive planet or companion star could have gravitationally pushed GJ 3090 b into its unusual orbit.

However, observations found no evidence of a sufficiently massive companion capable of causing the extreme tilt.

Scientists are now considering whether the star acquired a second, differently aligned disk of material from which the planet formed, giving it its unusual orientation from birth.

GJ 3090 b is also the smallest planet around an M dwarf for which astronomers have measured a complete three-dimensional orbital tilt.

Researchers said further observations are needed to test the proposed explanation. Scientists say the discovery offers insights into how planetary systems form and evolve. The findings were published in the journal Astronomy & Astrophysics.