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Proxima Centauri, our sun’s nearest neighbor

Proxima Centauri, one of three stars in the Alpha Centauri system, is our sun’s nearest known neighbor among the stars. It’s 4.22 light-years away.

Hubble Space Telescope image of Proxima Centauri, the closest known star to the sun.  Read more about this image.

Hubble Space Telescope image of Proxima Centauri, the closest known star to the sun. Read more about this image. Image via ESA/Hubble & NASA

Alpha Centauri A and B are a double-star system, and a third star Proxima – whose location with respect to the other two is indicated here by arrow – might or might not be gravitationally bound to them. Proxima is the closest star to Earth. Image via the European Southern Observatory.

The star Proxima Centauri isn’t visible to the eye, but it’s one of the most noted stars in Earth’s sky. That’s because it is considered to be part of the Alpha Centauri star system, a triple system, and the nearest star system to our sun. Of the three stars in Alpha Centauri, Proxima is thought to be the one actually closest to our sun, solar system and Earth. This image – from the Hubble Space Telescope – is one of the best we’ve seen at showing Proxima clearly.

Hubble’s Wide Field and Planetary Camera 2 (WFPC2) captured this view.

If it’s so nearby, why can’t we see Proxima Centauri with the eye? It’s because Proxima is so small. It’s red dwarf star with only about an eighth of the mass of the sun. Faint red Proxima Centauri – at only 3,100 K and 500 times less bright than our sun – is nearly a fifth of a light year from Alpha Centauri A and B.

This great distance from the two primary stars in the system is what calls into question its status as part of a triple star system.

On the other hand, although Proxima is far from Alpha Centauri A and B, it is not very far from us. And thus – over time – we can see its motion through space.

Bottom line: Hubble’s Wide Field and Planetary Camera 2 (WFPC2) captured this view of the Alpha Centauri system, the star system closest to our sun and Earth. Proxima Centauri, one of three stars in the Alpha Centauri system, is our sun’s nearest known neighbor among the stars. It’s 4.22 light-years away.

Read more from NASA about the image of Proxima Centauri

Read more about Alpha Centauri, the closest star system to our sun

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Deborah Byrd

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