Astronomers Detect Unusual Solar System 116 Light-Years Away

The newly discovered exoplanetary system challenges existing theories on how planets form around small stars.

Published on Feb. 15, 2026

Got story updates? Submit your updates here. ›

Astronomers have detected an exoplanetary system about 116 light-years from Earth that defies the typical pattern of planet formation. The system, orbiting the red dwarf star LHS 1903, features four planets arranged in an unexpected sequence - with the innermost and outermost planets being rocky, while the middle two are gaseous. This contradicts the common model where rocky planets orbit closer to the star and gas giants are farther away.

Why it matters

The discovery of this 'inside-out' planetary system challenges existing theories on how planets form around small, cool stars like LHS 1903. Understanding the formation of this unusual system could provide new insights into the complex processes that shape planetary systems throughout the galaxy.

The details

The planetary system was first detected using NASA's Transiting Exoplanet Survey Satellite (TESS) and then analyzed in detail with the European Space Agency's CHaracterising ExOPlanet Satellite (Cheops). Researchers tested various hypotheses to explain the presence of the outermost rocky planet, but could not attribute it to collisions or the remnant of a gas-rich planet. Instead, they propose a 'gas-depleted' formation mechanism where the planets formed sequentially from the inside out, with the outermost rocky planet forming much later when there was less gas and dust available in the disk.

  • The planetary system was first discovered in 2026 using the TESS space telescope.
  • The system was then analyzed in greater detail in 2026 using the Cheops satellite.

The players

Thomas Wilson

An assistant professor in the department of physics at the University of Warwick in England and first author of the study on the discovery.

Sara Seager

A professor of planetary science and physics at the Massachusetts Institute of Technology and a coauthor of the study.

Heather Knutson

A professor of planetary science at the California Institute of Technology who was not involved with the study.

Ana Glidden

A postdoctoral researcher at MIT's Kavli Institute for Astrophysics and Space Research who did not participate in the research.

Néstor Espinoza

An astronomer at the Space Telescope Science Institute in Baltimore who did not work on the study.

Got photos? Submit your photos here. ›

What they’re saying

“This formation mechanism, where you start with the inner one and then you move away from the host star, means the outermost planet formed millions of years after the innermost one. And because it formed later, there was actually not that much gas and dust in the disk left to build this planet from.”

— Thomas Wilson, Assistant Professor, University of Warwick (Science)

“Even in a maturing field, new discoveries can remind us that we still have a long way to go in understanding how planetary systems are built.”

— Sara Seager, Professor of Planetary Science and Physics, MIT (Science)

“Planet e is particularly intriguing, as it can potentially host many different kinds of atmospheres and may be cool enough for water to condense. This would be a fascinating planet to observe with the James Webb Space Telescope, which might be able to tell us more about its atmospheric properties.”

— Heather Knutson, Professor of Planetary Science, Caltech (Science)

“The authors reasonably conclude that the outermost planet likely formed in a region with little gas rather than losing its atmosphere through a violent collision.”

— Ana Glidden, Postdoctoral Researcher, MIT Kavli Institute (Science)

“This system adds a very interesting datapoint that will have planet formation models trying to explain it for years to come — and I'm sure we will learn something new about the process of planet formation once they are compared against each other!”

— Néstor Espinoza, Astronomer, Space Telescope Science Institute (Science)

What’s next

Future observations of the LHS 1903 system using powerful telescopes like the James Webb Space Telescope may provide more insights into the atmospheric properties of the planets, particularly the intriguing outermost rocky planet.

The takeaway

The discovery of the unusual 'inside-out' planetary system around the red dwarf star LHS 1903 challenges existing theories on how planets form around small, cool stars. Understanding the formation of this system could lead to new insights into the complex processes that shape planetary systems throughout the galaxy.