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Could an Earthlike planet with 2 stars be nearby?
People are fascinated by the idea of a planet orbiting more than one star, like Tatooine in “Star Wars” or Trisolaris in “The Three-Body Problem.” On September 29, 2026, researchers at the University of California, Riverside, said they have modeled a nearby binary star system and found that it could potentially support an Earth-sized planet in a habitable-zone orbit.
The researchers used 70 Ophiuchi as their model. This two-star system lies about 16 light-years away. Both of the stars in the 70 Ophiuchi system are a bit smaller and cooler than our sun. And while we’ve yet to find a planet orbiting either star, the UC Riverside astronomers said they’ve found that one could feasibly exist in a stable orbit around one of the two stars. And it could lie within the habitable zone of one of the stars, where liquid water would be stable on its surface.
The researchers published their peer-reviewed study on September 29, 2026, in The Astrophysical Journal.
Why look at 70 Ophiuchi?
The researchers targeted 70 Ophiuchi for their study. It’s a nearby star at around 16 light-years away, and people have been observing it for decades. From a dark-sky site, you can see it with the unaided eye as a single dim point of light at around magnitude 4 in the constellation Ophiuchus the Serpent Bearer.
With measurement data that goes back decades, the researchers were able to create a better model of what might happen there. Using their computer model, the researchers could then introduce an Earth-mass planet in different locations to see what happens to the system. Co-author Skylar D’Angiolillo of UC Riverside said:
We calculated the boundaries of the habitable zone around the primary star. Then I tested whether an Earth-mass planet could maintain a stable orbit at different distances within that zone.
What we found is that stable orbits are possible in the habitable zone of the primary star. You might expect the second star to disrupt those orbits, but that isn’t necessarily what happens.
D’Angiolillo added:
You can think of Earth’s orbit as being fairly circular. An unstable planet’s orbit can become increasingly elongated until eventually the planet is essentially flung away from the system. By repeating the simulation at different locations, we can identify regions where an Earth-sized planet could remain stable.
Our sun is the oddball
The sun does not have a stellar companion. And that makes it a bit of an oddball. The majority of stars that astronomers have studied come in pairs. In fact, some 85% of all sun-like stars in the Milky Way have either one or more companions. So finding that an Earthlike planet in a habitable orbit can exist in a binary system would be an important step toward understanding whether potentially habitable worlds can exist around the most common types of stars in our galaxy. Co-author Stephen Kane of UC Riverside said:
Having a 2nd sun may sound exotic, but we need to consider worlds that could be habitable without necessarily looking like Earth’s neighborhood.
D’Angiolillo added:
One reason this kind of work is important is that there are a lot of steps we can take before trying to directly observe a planet. We can ask first: Is this system even capable of hosting a potentially habitable planet?
That kind of dynamical vetting could be useful for the Habitable Worlds Observatory, a NASA mission planned for the 2040s that is intended to help search for potentially habitable worlds. There are many other binary systems that could benefit from this type of analysis as scientists begin considering possible targets.
But Kane said they will keep investigating 70 Ophiuchi in the meantime. Kane commented:
Who knows? We might actually discover an Earth-size planet in the habitable zone that Skylar has predicted could be there even before the Habitable Worlds Observatory launches.
Bottom line: Astronomers found that an Earthlike planet could have a stable and potentially habitable orbit around one of two nearby suns.
Source: A Century of Radial-velocity and Astrometric Monitoring of 70 Oph AB: New PFS Data and Constraints on Possible Planetary Companions
Via UC Riverside