A 'rebellious' exoplanet orbits in the opposite direction of its star
A star and its planets form when a cloud of gas and dust collapses in on itself somewhere in space. The cloud then forms a disk around the nascent star, within which the planets will form. This protostar and its disk then rotate in the same direction.
Astronomers have discovered that an exoplanet, GJ 3090 b, orbits in the opposite direction to its star, a phenomenon known as retrograde orbit. This is unusual as planets typically form and orbit in the same direction as their star. The planet, a sub-Neptune with a mass 4.5 times that of Earth, was detected by the TESS space telescope and confirmed by the NIRPS spectrograph.
The angle between the planet's orbital plane and the star's equatorial plane, known as Psi, is a staggering 136 degrees, positioning GJ 3090 b as one of only five such misaligned planets known. The discovery suggests the planet may have formed in a misaligned secondary disk around the star, a hypothesis that requires further investigation.
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