Some interesting thoughts on searching for intelligent life beyond the solar system.

Image by varrqnuht via Flickr

A prime target for our early efforts to find a twin Earth is our nearest star system, Alpha Centauri, 4.4 million light years away, (ED: actually it’s 4.4 light years away) which means that light (or an extraterrestrial message) takes 4.4 years to reach us.

It’s been the destination of interstellar travelers in science fiction writing for so long now that one would almost be forgiven for thinking we’d already colonized it. But Alpha Centauri, the three-star system closest to our own Sun, is now the center of some very exciting science.

Javiera Guedes who headed up a NASA-funded project to analyze the possibility of detecting an Earthlike planet in orbit around Alpha Centauri B, has shown that terrestrial planets are likely to have formed around Alpha Centauri B, and that these planets should be orbiting in the “habitable zone.”

“It’s so close to us, and the position of the other stars is such that it should be very possible to find a small planet,” she explained. She also found that, based on astronomers’ current understanding of how solar systems form, the existence of a planet the size of our own is very likely, and that there’s also a chance that it would lie in the habitable zone.

Now, the planet-hunting team is using a telescope in Chile to keep an eye on the star for the next three years, in order to collect enough data to determine whether or not the next Earthlike planet lies next door.

“If they exist, we can observe them,” said Guedes also showed that such planets would be observable if a telescope was dedicated to their search.

Guedes used a series of planet formation computer simulations to determine that terrestrial planets have probably formed around the star. The team ran repeated computer simulations which ran on a time frame of 200 million years each time. They varied the beginning conditions each time, and thus created a different result each time. However, each time a system of multiple planets evolved with at least one planet – approximately the size of Earth – forming. In many of these simulations, this planet was often found to be orbiting within the habitable zone of the star.

Its brightness and its position in the sky are both positive factors that make the Alpha Centauri search plausible; the latter giving the team a long period of observability each year from the Southern Hemisphere.

But the profound implication of the iron-clad law of astronomical time is that we see Alpha Centauri only as it was 4.4 years ago.In other words any message from inhabitants of Alpa Cenauri saying “Our planet is dying!” and our reply would consume a total of almost nine years.

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