Sunday, August 30, 2009

The Sun's Twin? (and does that mean another Earth as well?)

Another Sol?

An article by Bob Berman in this month's (Oct 2009) issue of Astronomy mentions that

of the 1,000 nearest stars within 3 dozen light-years, only one matches our Sun's temperature, size, and luminosity and has the same precise spectral class of G2V (a main sequence star with a surface temperature of about 9980 degrees Fahrenheit...).
In addition, that twin star is similar in age, though a bit older: the Sun is 4.6 billion years old, while this twin star is 5 to 6 billion years old.

One in a Thousand

That twin star? Alpha Centauri A. As Bob Berman points out - of all those 1,000 stars the only one that is the Sun's close twin is also the nearest naked-eye star (4.35 light-years away). An amazing coincidence. 

Hopefully the new generation telescopes, especially the whose main tasks are to search for exoplanets, will aim their sights on the Centauri trinary system. It would almost be criminal not to take a closer look. If there is a terrestrial planet circling Alpha Centauri A, the new generation telescopes should be able to find it. With Alpha Centauri A a bit older than the Sun, unless life evolved on Earth quicker than usual, a terrestrial planet in a habitable zone around Alpha Centauri A would have had plenty of time for sentient life to arise.

Long Distance Relationship

Of course, maybe sentient life does not survive its early years of sentience and there is no longer any sentient life to discover... But let us be optimistic for a moment and say that it survives. 4.35 light-years away would allow for communication via radio waves or laser. Sure, it would take 8.7 years for each message to be answered (4.35 years for it to travel there, and 4.35 years for the answer to travel back), but it still could be done.

But should we try to communicate with them? The wonders are tempting, but there is the possibility of danger...


"Alpha Centauri - A Candidate for Terrestrial Planets And Intelligent Life." Smoot Group Cosmology. The Smoot Group. 15 Oct. 1997. Web. 30 Aug. 2009. <>

Berman, Bob. "A dozen cool facts." Strange Universe. Astronomy. Oct 2009: 16. Print.

Image Credit: The Smoot Group.


Anonymous said...

Alpha Centauri B can have habitable worlds in closer orbits than A. That is important because that would make the orbits stabler in that trinary (for this purpose effectively binary) system.