Space & Astronomy

'Impossible' inside-out solar system discovered by astronomers

By T.K. Randall
February 13, 2026

Image: LHS 1903 Artist's Impression
Credit: European Space Agency / CC BY-SA 3.0 IGO (adapted) The ordering of planets within a solar system has long been considered universal across the cosmos, with rocky terrestrial worlds forming close to their star and gas giants farther out.

As it turns out, however, this isn't actually always the case.

On Thursday, astronomers revealed the discovery of the HS 1903 system - a place where the traditional ordering of planetary bodies seems to have been turned on its head.

Thanks to observations by Europe's exoplanet-probing Cheops space telescope, it was found that this peculiar solar system - which has a red dwarf star at its center - consists of one terrestrial world closest to the star, two giants further out, and then - bizarrely - another rocky world beyond that."That makes this an inside-out system, with a planet order of rocky-gaseous-gaseous-and then rocky again," said study lead author Thomas Wilson.

"Rocky planets don't usually form so far away from their home star."

The discovery suggests that there must be a planetary formation process that we currently do not understand.

"It seems that we have found first evidence for a planet that formed in what we call a gas-depleted environment," said Wilson.

Source: Science Alert

Tags: Planet, Solar System