Alpha Centauri

American  

noun

1. Astronomy. a triple-star system that is the brightest celestial object in the constellation Centaurus.

---

Alpha Centauri Scientific  

/ ăl′fəsĕn-tôr′ē /

1. A triple star system in the constellation Centaurus that is the third brightest star in the night sky, with an apparent magnitude of −0.27, and the star nearest to Earth, at a distance of about 4.2 light-years. The two brighter stars, Alpha Centauri A and B, form a binary star system, which is orbited by Proxima Centauri, a smaller, dimmer star.

---

Etymology

Origin of Alpha Centauri

< New Latin: Alpha of Centaurus

Example Sentences

The signs were found in the star system Alpha Centauri by the powerful James Webb Space Telescope.

From BBC • Aug. 8, 2025

By the way, that’s not me saying that I think the final answer is aliens visiting from Alpha Centauri.

From Los Angeles Times • Nov. 16, 2023

In the opening hours of the role-playing video game, it’s possible to land your spaceship on Earth’s moon or zip 16 light-years to Alpha Centauri.

From New York Times • Aug. 31, 2023

It took place at a location more than 8000 light-years away from our Earth in the direction of Alpha Centauri, between the constellations of Circinus and Centaurus.

From Space Scoop • Mar. 21, 2023

A ray of light from the sun follows the diagonal line, and takes four years to get from the sun to Alpha Centauri.

From "A Brief History of Time: And Other Essays" by Stephen Hawking