Barnard’s star, the nearest single star to the sun, has a brood of four small planets all its own, each about two to three times the mass of Mars and orbiting their star in less than a week.
The nearest single star to the sun, Barnard’s Star, has a brood of four small planets all its own. These close-in planets are each about two to three times the mass of Mars and orbit their star in less than a week.
Barnard's Star is a small, cool red dwarf star located about 5.98 light-years from the Sun in the constellation Ophiuchus.
It is the closest single star to the Sun and one of the most studied stars due to its proximity.
Barnard's Star has a mass of approximately 0.17 solar masses and a surface temperature of around 3,000 Kelvin.
Its low luminosity makes it difficult to observe, but its close proximity allows for detailed studies of its properties.
Astronomers have long been interested in studying the planetary system around Barnard’s Star, which is located about six light-years from Earth. In March 2025, a team of scientists published a study in the Astrophysical Journal Letters confirming the presence of four small planets in this system.
The discovery was made using two different spectrographs: MAROON-X on the Gemini North telescope in Hawaii and ESPRESSO on a telescope in Chile. The team observed Barnard’s Star 112 times between 2021 and 2023, but initially ignored some of the signals they detected due to instrument calibration issues.
Later, a new analysis using the ESPRESSO spectrograph revealed hints of three additional planets: c, d, and e. With this information, the team re-examined their data from MAROON-X and confirmed the existence of all four planets.
The Planets Themselves
All four planets are extremely close to Barnard’s Star, which has about one-seventh the mass of the sun. This means they orbit their star in less than a week, making them too hot to be habitable. In fact, the new observations probably rule out the presence of any habitable-zone planets.
The planets themselves range from at least 0.19 to 0.34 times the mass of Earth, which is a significant technological breakthrough given the limitations of previous instruments. The discovery was made possible by larger telescopes and improved control over temperature and pressure variations in the instruments.
A New Era for Exoplanet Detection
The detection of these small planets marks an important milestone in the study of exoplanets. For years, scientists have used the radial velocity method to detect changes in a star’s light caused by the gravitational pull of orbiting planets. This technique has been instrumental in identifying hundreds of planets around sunlike stars.
However, most of those planets are much more massive than Earth. The MAROON-X and ESPRESSO teams successfully detected much smaller planets using this technique, which is a significant advancement for future generations of telescopes.
Exoplanet detection involves identifying and characterizing planets outside our solar system.
Astronomers use a variety of methods, including the transit method, radial velocity method, and direct imaging.
The Kepler space telescope has been instrumental in discovering thousands of exoplanets since its launch in 2009.
According to NASA, over 4,000 exoplanets have been discovered so far, with many more expected to be found.
Exoplanet detection has expanded our understanding of planetary formation and the possibility of life beyond Earth.
Conclusion
The discovery of four small planets orbiting Barnard’s Star is an exciting development in the field of exoplanetary science. With its proximity to Earth and relatively low mass, Barnard’s Star makes it an ideal target for studying the properties of small planets. As scientists continue to refine their techniques and instruments, we can expect even more discoveries like this one in the years to come.
