![\"Schema](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2026\/04\/Schema-showing-how-a-planets-orbit-changes-under-Einsteins-gravity-in-a-two-star-system-1200x323.jpg\")
Schema showing how a planet\u2019s orbit changes under Einstein\u2019s gravity in a two-star system. Credit: The Astrophysical Journal Letters<\/p>\n
There is also a very specific blind spot. Binaries that orbit each other in less than seven days have no detected planets at all. According to UC Berkeley researcher Mohammad Farhat<\/a>, this creates a real \u201cdesert\u201d where planets seem to be missing entirely.<\/p>\n \u201cYou have a scarcity of circumbinary planets in general and you have an absolute desert around binaries with orbital periods of seven days or less,\u201d he said. \u201cThe overwhelming majority of eclipsing binaries are tight binaries and are precisely the systems around which we most expect to find transiting circumbinary planets.\u201d<\/p>\n When Einstein Enters the Picture<\/p>\n The explanation seems to come from a subtle effect. In these systems, both the stars and the planet experience orbital shifts known as precession, but not for the same reasons. As a team from UC Berkeley and the American University of Beirut explained, the stars\u2019 motion is affected by general relativity, especially as tidal forces slowly pull them closer together. That speeds up their motion, while the planet slows down.<\/p>\n At some point, the two motions sync up in what scientists call a resonance. That is where things go wrong. The planet\u2019s orbit stretches more and more until it becomes unstable. As Farhat explained, the planet is either pushed out of the system or pulled inward and lost. Simulations suggest nearly 80% of planets in these tight systems do not survive.<\/p>\n A Zone That Clears Everything Out<\/p>\n There is another key piece, the instability zone. This is a region around binary stars where stable orbits do not last. Jihad Touma<\/a> explainted that once a planet\u2019s orbit becomes too stretched, it drifts into this zone. <\/p>\n \u201cA planet caught in resonance finds its orbit deformed to higher and higher eccentricities, precessing faster and faster while staying in tune with the orbit of the binary, which is shrinking.\u201d Touma added, \u201cAnd on the route, it encounters that instability zone around binaries, where three-body effects kick into place and gravitationally clear out the zone.\u201d<\/p>\n Most of the circumbinary planets we do see sit just outside this boundary. That likely means they formed farther away and moved inward over time, stopping just before things became unstable. Touma describes forming planets near this region as \u201ctrying to stick snowflakes together in a hurricane,\u201d which reflects how chaotic it is.<\/p>\n![\"Diagram](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2026\/04\/Diagram-showing-where-planetary-orbits-become-unstable-in-two-star-systems-1200x1004.jpg\")
Diagram showing where planetary orbits become unstable in two-star systems. Credit: The Astrophysical Journal Letters<\/p>\n