Astronomy Swiss researchers discover messy planetary system
A rocky planet in the "wrong" place: researchers have used the Cheops space telescope to discover a planet that, according to conventional theories, should not be where it is. The discovery is forcing researchers to rethink the formation of planetary systems.
12.02.2026, 20:00
SDA
Until now, scientists have assumed that planetary systems follow a clear architecture, as the University of Bern explained in a press release on Thursday. The smaller rocky planets orbit close to the central star, while the large gas giants orbit further out.
However, the planetary system around a star called LHS 1903, which is 116 light years away from Earth, apparently does not follow this order. Using the Cheops space telescope, the international research team, which also includes researchers from the Universities of Bern and Geneva, discovered a rocky planet in a place where, according to current theories, a gas giant should actually have formed. The results were published in the journal "Science".
New theory was necessary
In order to explain this anomaly, the researchers first tested various hypotheses that could also be reconciled with current theories. They considered, for example, a collision that could have torn the planet's gas shell away, or a subsequent change in the orbits. However, none of these explanations were conclusive.
Instead, the team proposed a new theory. According to this theory, the planets in the system did not form simultaneously, but one after the other. Conventional theories on the formation of planets assume that planets in a planetary system always form simultaneously.
Diversity in space
According to the new theory, the planets formed around the star LHS 1903 from the inside out. The two gas giants in the interior of the system therefore formed when the protoplanetary disk was still rich in gas. The outer rocky planet formed much later. By this time, the gas in the disk had already disappeared, so that it could no longer accumulate a massive gas envelope and remained as a rocky planet.
According to the University of Bern, the discovery is one of a growing number of observations of "strange" planetary systems that are challenging established theories. According to the researchers, this shows that our solar system is not a universal model and that the diversity of planetary systems is greater than assumed.
