Four Tiny Planets Discovered Orbiting Barnard’s Star, Our Closest Stellar Neighbor

Barnard’s Star, located just six light-years from Earth, is once again in the spotlight. Long known as the closest solitary star to the Sun—and the fourth closest overall, after the Alpha Centauri system—this dim red dwarf has revealed four small planets orbiting it, offering an intriguing glimpse into the diversity of nearby planetary systems.

Tiny Worlds Around a Cool and Ancient Star

The new planetary discoveries around Barnard’s Star are especially notable because these exoplanets are all smaller than Earth, a rare find in astronomy. The planets were found to orbit the star extremely closely, with orbital periods ranging from just 2.3 to 6.7 days, making them far too hot to exist in the habitable zone.

The planets’ minimum masses range between 20% and 34% that of Earth, or about two to three times the mass of Mars. These are some of the smallest exoplanets ever detected, particularly notable given Barnard’s Star’s low luminosity and small size as an old M-type red dwarf.

Outside the Habitable Zone—But a Big Leap for Planet Detection

Although none of the planets lie within the habitable zone, current data rules out the presence of larger Earth-like planets (above 57% of Earth’s mass) with orbital periods between 10 and 42 days, which would have placed them in that potentially habitable region. This means the likelihood of habitable environments is low, at least for now.

Still, scientists are excited about what the discovery represents.

“It’s a really exciting find — Barnard’s Star is our cosmic neighbor, and yet we know so little about it,” said Ritvik Basant, lead author and graduate researcher at the University of Chicago.

Detected by the Star’s Wobble, Not Its Light

The planets around Barnard’s Star do not pass in front of the star from our viewpoint, meaning they can’t be studied via transit photometry, the method often used by missions like Kepler and TESS. Instead, astronomers relied on radial velocity measurements, detecting the slight wobble of the star as the planets pull on it gravitationally.

The most distant planet in the group is the smallest ever discovered using this technique, marking a milestone in precision astronomy.

Confirmed by Cutting-Edge Instruments

Previous generations of astronomers have long speculated about planets around Barnard’s Star, but only now, with next-generation instruments, has that become a confirmed reality.

Using tools like:

• MAROON-X, mounted on the Gemini North Telescope in Hawai‘i

• ESPRESSO, part of the Very Large Telescope array in Chile

…scientists were able to independently detect the same signals at different times and locations.

“Our teams didn’t coordinate with each other at all,” Basant explained. “That gives us a lot of assurance that these aren’t phantoms in the data.”