Why Tatooine-Like Exoplanets Are Rare in the Milky Way

Recent scientific research has provided new explanations for the scarcity of planets orbiting two stars, similar to the fictional world of Tatooine, within our galaxy.

Out of more than 6,000 confirmed exoplanets in the Milky Way, only a small fraction are known to orbit binary star systems. Astronomers had anticipated that about one in ten binary systems would host planets, a rate similar to single-star systems, but observations have revealed far fewer such planets.

Astrophysicists at the University of California, Berkeley and the American University of Beirut published findings indicating that general relativistic effects play a crucial role in the rarity of circumbinary planets. Their models show that in tight binary systems, where the stars orbit each other in seven days or less, planetary orbits are often destabilized and disrupted.

According to the research, general relativity causes the orbits of binary stars to precess, while Newtonian gravitational interactions also influence the precession of a planet’s orbit. When the rates of precession align, the planet’s orbit can become highly eccentric, increasing the likelihood of ejection or destruction.

What the numbers show

• There are over 6,000 confirmed exoplanets in the Milky Way
• Only 14 circumbinary exoplanets have been confirmed
• In tight binaries with periods of seven days or less, about 80% of potential planets are disrupted
• Kepler-16 b, the first confirmed circumbinary planet, was discovered in 2011

The study found that tight binary systems create an “absolute desert” for circumbinary planets, with roughly eight out of ten planets in these systems being destabilized by relativistic resonance. This mechanism helps explain why so few planets have been detected in these environments compared to initial expectations.

Despite these challenges, a few circumbinary planets have been directly observed. For example, HD 143811 AB b is a gas giant estimated to be six times the mass of Jupiter and orbits a binary system 446 light-years away with a period of 300 years. Another candidate, 2M1510, appears to orbit a pair of brown dwarfs in a polar orientation, as inferred from the unusual movements of the host stars.

The first confirmed circumbinary planet, Kepler-16 b, was identified in 2011. This planet orbits two stars with a period of about 229 days, providing a real-world example of a planet in a binary system, though such discoveries remain rare.

The research was published in The Astrophysical Journal Letters on December 8, 2025. These findings contribute to a better understanding of the physical processes that limit the formation and survival of planets in binary star systems.

* This article is based on publicly available information at the time of writing.