Astronomers have discovered three planets about the same size as Earth orbiting both stars in a rare double-star system called TOI-2267, about 190 light-years away. The discovery could change what we know about how planets form around two stars.

“This system is unusual,” said Sebastián Zúñiga-Fernández from the University of Liège. “Two planets orbit one star, and the third orbits the other. It’s the first time we’ve seen planets transiting both stars in a binary system.”

TOI-2267 is a very close pair of stars, which makes it hard for planets to form. Yet astronomers found three small rocky planets in short orbits, surprising scientists and challenging existing theories about planet formation.

“This discovery is a first in many ways,” said Francisco J. Pozuelos from the Instituto de Astrofísica de Andalucía. “It is the coldest and closest pair of stars known to have planets, and the first system where planets have been spotted around both stars.”

The planets were first spotted using NASA’s TESS space telescope. Astronomers at Liège and IAA-CSIC confirmed them with their own software called SHERLOCK and then followed up with ground-based telescopes, including SPECULOOS and TRAPPIST. These robotic telescopes are specially designed to study small planets around faint, cool stars.

“Finding three Earth-sized planets in such a tricky environment is a unique chance to study how planets form and survive in extreme conditions,” said Zúñiga-Fernández.

The discovery also opens up possibilities for future studies with the James Webb Space Telescope and other new observatories, which could reveal the planets’ masses, densities, and even atmospheres.