[22] The common name Rigil Kentaurus is a Latinisation of the Arabic translation رجل القنطورس Rijl al-Qinṭūrus, meaning "the Foot of the Centaur".

[48] To the naked eye, α Centauri AB appears to be a single star, the brightest in the southern constellation of Centaurus.

[50] Their apparent angular separation varies over about 80 years between 2 and 22 arcseconds (the naked eye has a resolution of 60 arcsec),[51] but through much of the orbit, both are easily resolved in binoculars or small telescopes.

In Ptolemy's time, Alpha Centauri was visible from Alexandria, Egypt, at 31° N, but, due to precession, its declination is now –60° 51′ South, and it can no longer be seen at that latitude.

English explorer Robert Hues brought Alpha Centauri to the attention of European observers in his 1592 work Tractatus de Globis, along with Canopus and Achernar, noting: Now, therefore, there are but three Stars of the first magnitude that I could perceive in all those parts which are never seene here in England.

[64]The binary nature of Alpha Centauri AB was recognized in December 1689 by Jean Richaud, while observing a passing comet from his station in Puducherry.

[65] The large proper motion of Alpha Centauri AB was discovered by Manuel John Johnson, observing from Saint Helena, who informed Thomas Henderson at the Royal Observatory, Cape of Good Hope of it.

The parallax of Alpha Centauri was subsequently determined by Henderson from many exacting positional observations of the AB system between April 1832 and May 1833.

He withheld his results, however, because he suspected they were too large to be true, but eventually published them in 1839 after Bessel released his own accurately determined parallax for 61 Cygni in 1838.

[16] Robert T. A. Innes discovered Proxima Centauri in 1915 by blinking photographic plates taken at different times during a proper motion survey.

Other conjunctions will also occur in the coming decades, allowing accurate measurement of proper motions and possibly giving information on planets.

[80] Based on the system's common proper motion and radial velocities, α Centauri will continue to change its position in the sky significantly and will gradually brighten.

By about 26,700 CE, in the present-day constellation of Hydra, α Centauri will reach perihelion at 0.90 pc or 2.9 ly away,[82] though later calculations suggest that this will occur in 27,000 AD.

[85] AB-C refers to the component of Proxima Centauri in relation to the central binary, being the distance between the centre of mass and the outlying companion.

Because the distance between Proxima (C) and either of Alpha Centauri A or B is similar, the AB binary system is sometimes treated as a single gravitational object.

[17][57][69] Until 2017, measurements of its small speed and its trajectory were of too little accuracy and duration in years to determine whether it is bound to Alpha Centauri AB or unrelated.

[5] Asteroseismic studies, chromospheric activity, and stellar rotation (gyrochronology) are all consistent with the Alpha Centauri system being similar in age to, or slightly older than, the Sun.

[89] Stellar evolution theory implies both stars are slightly older than the Sun at 5 to 6 billion years, as derived by their mass and spectral characteristics.

It is a solar-like main-sequence star with a similar yellowish colour,[97] whose stellar classification is spectral type G2-V;[3] it is about 10% more massive than the Sun,[90] with a radius about 22% larger.

It is a main-sequence star of spectral type K1-V, making it more an orange colour than Alpha Centauri A;[97] it has around 90% of the mass of the Sun and a 14% smaller diameter.

Because both stars are fairly similar to the Sun (for example, in age and metallicity), astronomers have been especially interested in making detailed searches for planets in the Alpha Centauri system.

[120][121] In 2009, computer simulations showed that a planet might have been able to form near the inner edge of Alpha Centauri B's habitable zone, which extends from 0.5–0.9 AU from the star.

In addition, the lack of any brown dwarfs or gas giants in close orbits around Alpha Centauri make the likelihood of terrestrial planets greater than otherwise.

[123] A theoretical study indicates that a radial velocity analysis might detect a hypothetical planet of 1.8 ME in Alpha Centauri B's habitable zone.

[130] Such ideas also apply to the close approach of Alpha Centauri or other stars to the Solar system, when, in the distant future, the Oort Cloud might be disrupted enough to increase the number of active comets.

[82] To be in the habitable zone, a planet around Alpha Centauri A would have an orbital radius of between about 1.2 and 2.1 AU so as to have similar planetary temperatures and conditions for liquid water to exist.

[134] Based on observations between 2007 and 2012, a study found a slight excess of emissions in the 24 μm (mid/far-infrared) band surrounding α Centauri AB, which may be interpreted as evidence for a sparse circumstellar disc or dense interplanetary dust.

It would be at the antipodal point of α Centauri AB's current right ascension and declination, at 02h 39m 36s +60° 50′ 02.308″ (2000), in eastern Cassiopeia, easily outshining all the rest of the stars in the constellation.

Sirius, at 9.2 light years away from the system, would still be the brightest star in the night sky, with a magnitude of -1.2, but would be located in Orion less than a degree away from Betelgeuse.

[142][144] NASA released a mission concept in 2017 that would send a spacecraft to Alpha Centauri in 2069, scheduled to coincide with the 100th anniversary of the first crewed lunar landing in 1969, Apollo 11.