: : : I'm a complete novice to astronomy but am interested in some "expert" opinions for some fiction I am considering writing. What I'd like to know is whether its possible that an inhabitable (by humans) planet might orbit Alpha Centauri 1 in such a way that it actually passes between Alpha Cent. 1 & Alpha Cent. 2, during its year. Is that possible and if it is, what might conditions be like on such a planet? I do not know how close together the stars of the Alpha Centauri system are to one another but I assume there is plenty of room for a planet to orbit one of them? I'm looking for feasible stuff for the imagination here. : : : Thanks.

: : it is plausable that life can exist on a planet such as Alpha Centauri since it could because there are other types of life forms other than human. : these could be water based,silicon based,rock based,just because there is no ideas that humans could exist.doesn't stop the idea that life could exist.

Found this at the following web site:

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970717b.html

Hope it helps

The Question

We would like to find out some information on the star, Alpha Centauri. We are 10 years old, but already have followed up a great interest in astronomy. We would especially like to know what Alpha Centauri is made of, what its measurements are and if it has any special assets.

The Answer

Here are some facts about Alpha Centauri:

Visible only from latitudes south of about 25 degrees S, the star we call Alpha Centauri lies 4.35 light-years from the Sun. But it is actually a triple star system. The two brightest components Alpha Centauri A and B form a binary. They orbit each other in 80 years with a mean separation of 23 astronomical units (1 astronomical unit = 1 AU = distance between the Sun and Earth). The third member of the system Alpha Centauri C lies 13,000 AU from A and B, or 400 times the distance between the Sun and Neptune. This is so far that it is not known whether Alpha Centauri C is really bound to A and B, or if it will have left the system in some million years. Alpha Centauri C lies measurably closer to us than the other two: It is only 4.22 light-years away, and it is the nearest individual star to the Sun. Because of this proximity, Alpha Centauri C is also called Proxima (Centauri).

Alpha Centauri A is a yellow star with a spectral type of G2, the same as the Sun's. Therefore its temperature and color also match those of the Sun. Alpha Centauri B is an orange star with a spectral type of K1. Whereas Alpha Centauri A and B are stars like the Sun, Proxima is a dim red dwarf with a spectral type of M5 - much fainter, cooler, and smaller than the Sun. Proxima is so faint that astronomers did not discover it until 1915.

I hope this helps!

Tim Kallman for Ask a NASA Scientist