Alpha Centauri is the closest star system to the Sun. Its two bright stars, Alpha Centauri A and B, are 4.37 light-years away and together look like the third-brightest star in the night sky. A small red dwarf, Proxima Centauri, orbits them and is the single closest star to us. Alpha Centauri is a southern-sky star: you need to be south of about 29°N to see it.
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Alpha Centauri at a glance
| Other names | Rigil Kentaurus (A), Toliman (B), Proxima Centauri (C) |
|---|---|
| Constellation | Centaurus |
| Brightness | Magnitude −0.27 for A and B together, third-brightest star |
| Distance | 4.37 light-years (A and B); Proxima 4.24 light-years |
| Alpha Centauri A | Sun-like yellow star (G2V), about 1.1 Suns in mass |
| Alpha Centauri B | Orange star (K1V), about 0.9 Suns in mass |
| Orbit of A and B | About 80 years |
| Proxima Centauri | Red dwarf about 13,000 times the Earth–Sun distance from A and B |
| Best time to see it | Evenings around June (highest at about 9 p.m.) |
| Where on Earth | Visible from everywhere south of about 29°N; never sets south of about 29°S |
Three stars in one system
To the naked eye Alpha Centauri looks like a single brilliant star, but it is a family of three. Alpha Centauri A is very similar to our Sun, slightly larger and brighter. Alpha Centauri B is a little smaller and cooler, an orange star. The two orbit each other every 80 years or so, at a distance that varies between roughly the distance of Saturn and Pluto from the Sun. A small telescope splits them into a beautiful pair.
The third member, Proxima Centauri, is a dim red dwarf about 0.2 light-years from the bright pair, so far away that it takes it hundreds of thousands of years to complete one orbit. It is too faint to see without a telescope, yet it is the single star closest to the Sun, at 4.24 light-years.
Does Alpha Centauri have planets?
Proxima Centauri has at least one confirmed planet, Proxima b, an Earth-mass world in the star’s habitable zone, plus a smaller one, Proxima d. The two Sun-like stars are harder to search. In August 2025, astronomers using NASA’s James Webb Space Telescope reported a candidate giant planet around Alpha Centauri A: a faint object, possibly about the mass of Saturn, orbiting within the star’s habitable zone at roughly 1 to 2 times the Earth–Sun distance. It was not seen in every observation, so it is still a candidate, and follow-up imaging is planned. If confirmed, it would be the closest planet to Earth ever directly imaged. A giant planet like this could not host life as we know it, though any large moons might be interesting.
How long would it take to reach Alpha Centauri?
Light takes 4.37 years. Our fastest-travelling spacecraft would take far longer. Voyager 1, moving at about 17 km per second, would need roughly 75,000 years to cover the distance (and it is not heading that way). The Breakthrough Starshot project has proposed sending tiny light-sail probes, pushed by powerful lasers, at a fifth of the speed of light, which would cut the trip to about 20 years, but the technology does not exist yet.
How to see Alpha Centauri
Alpha Centauri lies deep in the southern sky at a declination of about −61°. That means it never rises for anyone north of about 29°N: it is invisible from the United States (apart from the very south of Texas and Florida, where it barely clears the horizon), Europe and most of China, but visible from southern India and very well placed from Australia, South Africa and South America. From the Southern Hemisphere it is a circumpolar star south of about 29°S, never setting.
Alpha Centauri and its neighbour Beta Centauri (Hadar) are known as the Pointers, because a line from Alpha through Beta points to the Southern Cross (Crux). The pair is highest in the evening sky from about April to July. Use the live tool above to see whether it rises at your location and when.
Names and history
The traditional name of Alpha Centauri A is Rigil Kentaurus, from Arabic for “the foot of the Centaur”; in 2018 the International Astronomical Union also gave Alpha Centauri B the name Toliman. The system’s nearness was first measured in the 1830s by Thomas Henderson at the Cape of Good Hope, one of the first measurements of the distance to any star. Because Alpha Centauri is moving towards us, it will come a little closer, to about 3 light-years, in roughly 28,000 years.
Frequently asked questions about Alpha Centauri
How far away is Alpha Centauri?
Alpha Centauri A and B are about 4.37 light-years away, roughly 41 trillion kilometres. Proxima Centauri, the third star in the system, is slightly closer at 4.24 light-years.
Is Alpha Centauri the closest star?
The Alpha Centauri system is the closest star system. The single closest star is its smallest member, Proxima Centauri.
Does Alpha Centauri have a planet?
Proxima Centauri has at least two planets. In 2025 the James Webb Space Telescope found a candidate giant planet around Alpha Centauri A, which still needs confirmation.
Can I see Alpha Centauri from the USA or Europe?
No, except from the far south of Texas and Florida, where it barely rises. You need to be south of about 29°N, for example in southern India, Australia or South America.
How long would it take to travel to Alpha Centauri?
With today’s spacecraft, tens of thousands of years. Voyager 1’s speed would need about 75,000 years.
Sources: NASA/IPAC: JWST finds new evidence for a planet around Alpha Centauri A (Aug 2025); Alpha Centauri overview and references. Star data from standard catalogues; positions and rise/set times are calculated by SpaceTracker.live with the Astronomy Engine library.