Tuesday, April 24, 2007

Now aiming SETI dishes at Gliese 581

How do you pronounce Gliese anyway? We need a better name than Gliese 581 for this large rocky planet in a "temperate" orbit around a smaller, colder, Sun:
BBC NEWS | Science/Nature | New 'super-Earth' found in space

... The Gliese 581 super-Earth is in what scientists call the 'Goldilocks Zone' where temperatures 'are just right' for life to have a chance to exist.

Commenting on the discovery, Alison Boyle, the curator of astronomy at London's Science Museum, said: 'Of all the planets we've found around other stars, this is the one that looks as though it might have the right ingredients for life.

'It's 20 light-years away and so we won't be going there anytime soon, but with new kinds of propulsion technology that could change in the future. And obviously we'll be training some powerful telescopes on it to see what we can see,' ...
Twenty light years? Might as well be next door. I trust the radio dishes will try to sneak a listen. It's unlikely that we'll pick up any television, but it never hurts to listen :-).

I wonder how old the sun of Gliese 581 is.... I'll pronounce it Gleesee for now ...

Update: Much more information here ... I thought I was being facetious about the SETI dish. Emphases mine. Note the star is Gliese 581, the planet, for now, is Gliese 581c.

... The star at the centre - Gliese 581 - is small and dim, only about a third the size of our Sun and about 50 times cooler.

The two other planets are huge, Neptune-sized worlds called Gliese 581b and d (there is no "a", to avoid confusion with the star itself).

The Earth-like planet orbits its sun at a distance of only six million miles or so (our Sun is 93 million miles away), traveling so fast that its "year" only lasts 13 of our days...

... Just because Gliese 581c is habitable does not mean that it is inhabited, but we do know its sun is an ancient star - in fact, it is one of the oldest stars in the galaxy, and extremely stable. If there is life, it has had many billions of years to evolve.

This makes this planet a prime target in the search for life. According to Seth Shostak, of the Search for Extraterrestrial Intelligence Institute in California, the Gliese system is now a prime target for a radio search. 'We had actually looked at this system before but only for a few minutes. We heard nothing, but now we must look again.'

By 2020 at least one space telescope should be in orbit, with the capability of detecting signs of life on planets orbiting nearby stars. If oxygen or methane (tell-tale biological gases) are found in Gliese 581c's atmosphere, this would be good circumstantial evidence for life.

... The real importance is not so much the discovery of this planet itself, but the fact that it shows that Earth-like planets are probably extremely common in the Universe.

There are 200 billion stars in our galaxy alone and many astronomers believe most of these stars have planets.

The fact that almost as soon as we have built a telescope capable of detecting small, earth-like worlds, one turns up right on our cosmic doorstep, shows that statistically, there are probably billions of earths out there.

... Interestingly, Gliese 581c is so close to the Earth that if its putative inhabitants only had our level of technology, they could - just about - pick up some of our radio signals, such as the most powerful military transmitters. Quite what would happen if we for our part did receive a signal is unclear...
This type of discovery further reduces the degrees of freedom in the Drake Equation, pushing the resolution of the Fermi Paradox further towards the "go no more a roaming" answer.

The SETI home page has an article on M Class suns, which I think includes Gliese 581.
...M-Stars, are of interest simply because there are so many of them—they are the most common star in the galaxy. They’re the cool stars that inhabit our neighborhood...

... There’s considerable interest in the question of whether M-Stars could host habitable planets. Would the planets be tidally locked with one face always directed toward the M-Star? Would flares wipe out life on the local planet? If M-Stars could host habitable planets, life may be much more widespread that we’ve previously thought...

...Dr. Peter Backus, Observing Programs Manager for SETI, concluded in a preliminary report on the M-Stars workshop, “One…aspect of M dwarfs makes them intriguing for SETI: they may be ideal hosts for advanced technological civilizations because they live an extraordinarily long time. Stars like the Sun live (i.e., they fuse hydrogen into helium) for only about 10 billion years. No M dwarf that ever formed has yet to die; no M dwarf will die for more than another 100 billion years. With such long lifetimes, there are big possibilities for these small stars.”
Update: Much more here, in a blog dedicated to this topic.

1 comment:

James Brown said...

Thanks for the information Gordon. I have a small SETI station of my own and will start scanning that star location in the morning. You can watch my progress at:

Regards... Jim