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The star we call Alpha Centauri is actually a triple system. This image shows the sizes and colors of the three stars compared to the Sun.
Click on image for full size

Alpha Centauri - The Sun's Twin (almost)

What's in a Name: Sometimes called Rigel Kentaurus meaning "foot of the Centaur" in Arabic.
Claim to Fame: Member of the triple star system closest to our sun. 3rd brightest star in the sky (apparent visual magnitude = -0.3).
Type of Star: Yellow-Orange Main Sequence star (G2 V Spectral Class).
How Far Away: 4.3 light years away
How Big: About the same size as the sun
How Bright: 40% brighter than the sun. Absolute visible magnitude Mv = +4.4
Where to View: Located in the constellation Centaurus, the Centaur (Star Map)
When to View: Centaurus is never in the sky viewed from middle northern latitudes (around 40 degrees). As you travel south on the Earth's surface and pass below the equator, you will definitely see it from time to time.

Last modified March 3, 2005 by Travis Metcalfe.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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