A circumtriple planet is a celestial mass that is hypothesized to be orbiting not only a single star but three stars at the same time. Scientists observing the star system GW Ori, which is a huge disk of dust and gases about 1,300 light years away from Earth, suspect that there may be a circumtriple planet orbiting the three stars. They observed a gap in the vast dust cloud and they hypothesize that there may be a planet in this gap. The planet itself has not been seen but its influence may explain gravitational oddities within the star system. By using computer modeling, some scientists believe that a Jupiter-sized planet may be able to explain the star system's rings and strange behavior, according to one account. If so, this may be the first known example of a circumtriple planet in the universe.
In 2024, the substellar object CWISE J235827.96–521813.4 was detected to be bound to the Gliese 900 triple star system at a distance of 12000 AU,[1] thus becoming the planet with the longest orbital period.
If a circumtriple planet exists, it will be an extremely rare phenomenon in the universe. It could add to human understanding of how planets form.
A circumtriple planet is prominently featured in the Remembrance of Earth's Past book series. In the series, the planet of Trisolaris orbits a three-star system, and the chaotic nature of the system drives the native species of the planet to seek refuge on Earth, which has a comparatively more "stable" one-star system.