Astronomers Discover Rare Inside-Out Planetary System

University of Warwick team finds a distant rocky world orbiting a red dwarf star, defying conventional planet formation models.

Published on Feb. 13, 2026

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Astronomers from the University of Warwick, using the ESA's CHEOPS telescope, have discovered a unique planetary system around the red dwarf star LHS 1903. The system contains four planets, including a distant rocky world that orbits outside the expected gas giant planets, challenging conventional theories of how planets form.

Why it matters

This discovery of an "inside-out" planetary system provides new insights into the diversity of planetary formation processes in the universe. It suggests that rocky planets can form in gas-depleted environments, expanding our understanding of how planetary systems evolve beyond the patterns observed in our own Solar System.

The details

The planetary system around LHS 1903 begins with a rocky planet orbiting close to the star, followed by two gas giant planets, and then surprisingly, a fourth planet that is also rocky, orbiting at the outer edge of the system. This "inside-out" configuration defies the typical pattern of rocky inner planets and gas giants farther out. The researchers ruled out theories that the planets may have swapped positions or that the rocky planet lost its atmosphere, and instead concluded that the planets formed one after another in a process called "inside-out planet formation", where each planet evolves in turn rather than all forming simultaneously.

  • The discovery was published in the journal Science on February 13, 2026.

The players

Dr. Thomas Wilson

Assistant Professor in the Department of Physics at the University of Warwick and lead author of the study.

University of Warwick

The institution where the astronomers who made this discovery are based.

ESA

The European Space Agency, whose CHEOPS telescope was used to observe the planetary system around LHS 1903.

LHS 1903

A cool, faint red dwarf star around which the unique planetary system was discovered.

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What they’re saying

“This strange disorder makes it a unique inside-out system. Rocky planets don't usually form far away from their home star, on the outside of the gaseous worlds.”

— Dr. Thomas Wilson, Assistant Professor, University of Warwick (Mirage News)

“Historically, our planet formation theories are based on what we see and know about our Solar System. As we are seeing more and more different exoplanet systems, we are starting to revisit these theories.”

— Isabel Rebollido, Research Fellow, ESA (Mirage News)

“Much about how planets form and evolve is still a mystery. Finding clues like this one for solving this puzzle is precisely what CHEOPS set out to do.”

— Maximilian Günther, CHEOPS Project Scientist, ESA (Mirage News)

What’s next

Further observations and analysis of the LHS 1903 planetary system will be needed to fully understand how this "inside-out" configuration formed and what it means for our theories of planet formation.

The takeaway

This discovery of an unusual planetary system around the red dwarf star LHS 1903 challenges our conventional understanding of how planets form and evolve. It suggests that rocky worlds can form in gas-depleted environments, expanding the diversity of planetary systems in the universe.