Scientists have studied Proxima Centauri for over a century, using increasingly powerful tools to learn about the closest star to our Sun. At just 4.24 light-years away, it occupies a unique position in astronomy: close enough to study in unusual detail, yet still impossibly far to visit with current technology. The methods used to research this small, dim star range from early photographic plates to orbiting space telescopes and precision spectrographs capable of detecting the gravitational tug of a planet smaller than Earth.
Finding the Nearest Star
Proxima Centauri was discovered in 1915 by Robert Innes, director of the Union Observatory in Johannesburg, South Africa. Innes identified a faint star with an unusually large “proper motion,” meaning it appeared to move across the sky faster than most other stars. That rapid apparent movement was a clue that the star was extremely close to us in cosmic terms. Further measurements of its parallax (the tiny shift in position caused by Earth’s orbit around the Sun) confirmed it was the nearest known star.
Despite being our nearest stellar neighbor, Proxima Centauri is far too dim to see with the naked eye. It has about 15% the mass of the Sun and roughly one-seventh the Sun’s diameter, making it a red dwarf, the most common type of star in the Milky Way. Its faintness is precisely why it wasn’t noticed until the early 20th century, even though the brighter Alpha Centauri pair it orbits had been observed for centuries.
Detecting Planets Through Stellar Wobbles
The most consequential research on Proxima Centauri in recent decades has focused on finding planets orbiting it. Scientists use a technique called the radial velocity method: they measure incredibly small shifts in the wavelength of a star’s light caused by the gravitational pull of an orbiting planet. As a planet tugs its star slightly toward and away from Earth, the star’s light shifts blue and red in a repeating cycle. The size and timing of that wobble reveal a planet’s minimum mass and orbital period.
In 2016, a team led by Guillem Anglada-Escudé at Queen Mary University of London announced the discovery of Proxima Centauri b. They found it by running analysis algorithms on years of archival data from two instruments operated by the European Southern Observatory in Chile: the Very Large Telescope and the High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory. The archival data showed hints of a periodic wobble, which the team then confirmed with a dedicated months-long observing campaign in early 2016. Proxima b turned out to orbit within the star’s habitable zone, the range of distances where liquid water could theoretically exist on a rocky surface.
Scientists later pointed an even more sensitive instrument at the star. The ESPRESSO spectrograph, also mounted on the Very Large Telescope, can detect stellar wobbles as small as tens of centimeters per second. Using ESPRESSO data, researchers identified Proxima d, a planet with a minimum mass of about 0.26 times that of Earth (roughly twice the mass of Mars) orbiting the star every 5.12 days at a distance of just 0.029 astronomical units. They also found evidence of a third planet candidate, Proxima c, with an orbital period of close to five years. Each successive discovery required instruments precise enough to tease out smaller and smaller signals buried in stellar noise.
Monitoring Flares From Space
Proxima Centauri is far more volatile than our Sun. NASA’s Transiting Exoplanet Survey Satellite (TESS) stared at the star continuously for about 50 days and recorded 72 separate flare events, a rate of roughly 1.5 flares per day. During this observation window, the star was actively flaring 7.2% of the time. The individual flare energies ranged from about 10^30 to 10^32 ergs in the TESS observing band.
These are not just minor brightenings. Based on the distribution of flare energies, researchers estimate that superflares (eruptions releasing at least 10^33 ergs, or roughly 10 times the energy of the most powerful solar storm ever recorded on Earth) strike about three times per year. Events ten times more energetic than that are expected roughly every two years. This flare data is critical for understanding whether any planet orbiting Proxima Centauri could retain an atmosphere, since each flare blasts orbiting worlds with intense radiation.
Assessing Habitability Through Radiation Models
Finding a planet in the habitable zone is one thing. Figuring out whether it could actually support life requires a different kind of research: modeling the radiation environment. Because Proxima Centauri is so dim, its habitable zone sits very close to the star. That proximity means Proxima b is exposed to extreme ultraviolet radiation hundreds of times greater than what Earth receives from the Sun.
NASA-funded simulations have modeled what would happen to an Earth-like atmosphere in that environment. The results are sobering. The star’s intense radiation would strip away atmospheric gases as much as 10,000 times faster than the Sun erodes Earth’s atmosphere. Over geological timescales, that could leave Proxima b essentially airless, unless some replenishment mechanism (such as volcanic outgassing) keeps pace with the losses. This line of research combines stellar observations, flare data, and atmospheric physics to paint a picture of conditions on a world no telescope can directly image yet.
Pushing the Limits of Direct Observation
The James Webb Space Telescope (JWST) represents the current frontier for studying Proxima b’s atmosphere. Researchers have proposed using JWST’s mid-infrared instrument to search for carbon dioxide at 15 micrometers using a spectral filtering technique. In theory, if Proxima b has an Earth-like atmosphere, carbon dioxide could be detected within a few days of dedicated observations.
The practical challenges are steep. JWST cannot spatially separate the planet from its star because its mirror is not large enough to resolve the tiny angular distance between them (about 37 milliarcseconds at maximum). Instead, scientists would need to detect the planet’s thermal signature blended with the star’s light, a contrast of up to 100 parts per million. Pulling that signal out requires knowing the instrument’s response and the star’s own spectrum to a relative precision of one part in 10,000 between adjacent wavelength channels. The next generation of extremely large ground-based telescopes, still 5 to 10 years away, could eventually overcome some of these limitations.
Planning to Send a Spacecraft
The most ambitious research effort aimed at Proxima Centauri does not involve telescopes at all. Breakthrough Starshot, a privately funded initiative, is developing a concept to send tiny spacecraft to the Alpha Centauri system using ground-based lasers. The idea is to push a sail just a few meters across with a powerful, coherent laser beam, accelerating it to one-fifth the speed of light. At that speed, the craft would reach Proxima Centauri in about 20 years, with another four years needed for any signal to travel back to Earth at light speed.
The project is currently in a research and development phase expected to last a decade or more. The core engineering challenge is combining thousands of small lasers into a single coherent beam powerful enough to accelerate the sail. The spacecraft themselves would be gram-scale “wafer sats” carrying cameras and basic instruments. If it works, it would deliver the first close-up data on another star system, turning Proxima Centauri from a point of light into an actual destination.