Earth-sized planets could survive in nearby binary star system 16 light-years away

The idea of a planet orbiting two suns has captivated us since long before Star Wars—the concept appeared in literature over a century earlier. But the real question has always been whether such worlds could actually exist, and whether they might harbor life. A new study suggests the answer is yes, at least in one nearby corner of the galaxy.

Astronomers have focused their attention on 70 Ophiuchi, a binary star system just 16 light-years from Earth. The two stars in this system are K dwarfs, smaller and dimmer than our Sun but potentially far longer-lived—they could burn for up to 70 billion years compared to the Sun's 10 billion. The system has been known to exist as a binary for nearly 250 years, since William Herschel first identified it. What makes it particularly compelling is its proximity and stability, making it an ideal laboratory for testing whether Earth-sized worlds could survive in such an environment.

The research team, drawing from more than a dozen institutions, assembled a century of observational data using radial velocity measurements—a technique that detects the subtle wobble a star makes when a planet's gravity tugs on it. The precision they achieved was extraordinary: better than one meter per second, equivalent to detecting a person's slight change in walking speed. They analyzed data from eight different instruments trained on the primary star, building an exceptionally detailed picture of the system's dynamics.

Using this foundation, the researchers ran simulations testing whether Earth-mass planets could maintain stable orbits within the habitable zone around the primary star. They modeled 2,000 different planetary positions and tracked them over 10 million years of simulated time. The results challenged a long-held assumption: that a second star would act as a gravitational wrecking ball, destabilizing any planets in the system. Instead, the simulations revealed that stable orbits were entirely possible. "You might expect the second star to disrupt those orbits, but that isn't necessarily what happens," explained one of the study's co-authors.

The research also resolved a historical mystery. In 1855, British astronomer William Jacob claimed to have discovered a planet around 70 Ophiuchi, which would have made it the first exoplanet ever identified—more than a century before the first confirmed discovery. Later observations seemed to support his claim, showing a wobble that could indicate a Jupiter-sized giant planet. But the new analysis ruled out any giant planets in the system out to about five astronomical units from the primary star. The supposed signal, it turned out, was simply stellar activity—noise that has long plagued the radial velocity method.

This finding carries both disappointment and possibility. There is no massive planet hiding in 70 Ophiuchi, ending a tantalizing historical claim. But the absence of detection does not mean absence of planets. Earth-mass worlds remain below the detection threshold of current instruments, meaning they could exist undetected. The simulations now provide a roadmap: researchers know where such planets would be stable and habitable if they exist.

The implications extend far beyond this single system. More than half of all stars in the galaxy have stellar companions, meaning binary systems are the norm rather than the exception. If Earth-sized planets can survive in these systems—and the evidence from 70 Ophiuchi suggests they can—then the potential locations for habitable worlds multiply dramatically. Future telescopes, particularly NASA's planned Habitable Worlds Observatory, will have the capability to directly image planets in such systems, finally allowing astronomers to see what has long remained hidden in the data.