An astronomer picked up a mysterious pulse of light coming from the direction of the newly discovered Earth-like planet almost two years ago, it has emerged.
Dr Ragbir Bhathal, a scientist at the University of Western Sydney, picked up the odd signal in December 2008, long before it was announced that the star Gliese 581 has habitable planets in orbit around it.
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He went on: ‘We found this very sharp signal, sort of a laser lookalike thing which is the sort of thing we’re looking for – a very sharp spike. And that is what we found. So that was the excitement about the whole thing.’
The Mote In Gliese’s Eye?
UPDATE: Yet again, journalism FAIL: http://www.space.com/common/forums/viewtopic.php?t=19192
The signal we detected came from the southern constellation Tucanae.
Note that that’s not the constellation that Gliese 581g happens to be in.
About Gliese 581g: http://apod.nasa.gov/apod/ap101001.html
The best fit to the data indicate the planet has a circular 37 day orbit, an orbital radius of only 0.15 AU, and a mass 3.1 times the Earth’s. Modeling includes estimates of a planet radius of 1.5, and gravity at the planet’s surface of 1.1 to 1.7 in Earth units.
At 1.7 G’s surface gravity, it would be an uncomfortable place… but not unlivable for adapted Terrestrial life… and certainly not for life locally evolved. One complaint I’ve seen is that since the planet is so close to it’s relatively small star, it would be tidally locked, meaning one side perpetually faces the sun, one side perpetually faces away. Some people thus assume that this means that the only livable spot would be along the terminator, where the sun is just on the horizon. But there are two additional possibilities:
1) The planet has a moon in close orbit. If so, it will be tidally locked to *that.* The moon would have to be in pretty close, which means it would loom incredibly large in the sky. A sizable moon would also remove some of the detected mkass of the planet, and reduce the surface gavity.
2) If the planet has any axial tilt, then the terminator is not a fixed band, but a much broader area. At the poles, the sun would seem to go up and down on a 37-Earth-day cycle. However, tidal locking would probably wipe out axial tilt over time.
11 Responses to “Optical signal from Gliese 581g? (UPDATE: bunk)”
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With a setup of that sort, the first thing the natives would have explored would be not space but the two uninhabitable zones. The down side that comes to mind first, though, is the fact that the local sun is so near. What would that suggest for radiation of all sorts?
My overnight bag is packed, if anyone has a way to visit the place this weekend.
Thing is, it’s only 20 light years away. If they were at our level of technology (which, to produce a laser light like that you’d have to be – at least) would their radio output be powerful enough for us to detect at this distance? We always hear about Hitler’s speech propagating throughout space, but the signal gets weaker and weaker the further it travels. Would we be able to detect a signal transmitted at those levels from this distance?
Red dwarfs are old but slow burning. Glise has gotten some attention before because it’s pretty stable and so might not have made its habitable zone unpleasant with flares.
Oe other bit. If its that close and rocky, the planet almost certainly has a strong magnetic field due to tidal stresses, like Ganymede.
On a related note
While things are awkward right now we need to start thinking about some really cool, over the top, utterly insane and awe inspiring thing to do for the tricentennial celebration….
According to http://www.reddit.com/r/science/comments/dkw5a/does_anybody_else_think_its_interesting_that_in/ that report is in error.
I don’t have much faith in the Daily Mail, they can’t get even the basic facts of the story right:
“Its star is a red giant – a massive star near the end of its life. It is too dim to see in the night sky from Earth without a telescope.”
It’s a red dwarf, not a red giant. Pretty damn big detail to get wrong.
Somebody wake me when the story gets straightened out.
> Would we be able to detect a signal transmitted at those levels from this distance?
Probably not. My understanding is that terrestrial TV signals disappear within about a light year… they get “washed out” by the background noise, and can’t be detected any further than that. The DEW line radars can be detected much further away, but those would be detected as just brief flashes as the Earths rotation sweeps them past observers.
If it is tidally locked, with life developing around the terminator, then there would be a real evolutionary advantage for life to expand outwards into the virgin areas of the light and dark sides, the way it moved from the sea unto land here on Earth.
Yeah, it would have to be tidally locked into a 1:1 spin-orbit resonance, so it would be a one-face world just like Mercury is in our solar system.
(That’s sarcasm. Mercury isn’t a one-face world, and there are other spin-orbit resonances than 1:1 that could give Gl 581g a day of “reasonable” length.)
One thing I don’t recall reading anywhere is just how visible Earth might be. Using what is available to us today, from how far away could Earth be recognized as a planet that might have life?
Using technology that we have, though parhaps not *deployed*, Earth should be recognizable as a life-bearing world from several dozen lightyears away, at least. With a bigger space telescope than Hubble (perhaps Webb-sized), Earth might not be resolvable as a disk, but it could be spectrally analyzed, and the evidence of free oxygen and water vapor should be easily detectable. Large quantities of free oxygen on a small planet would be difficult to explain without life. Wipe out *all* life on Earth, and the oxygen will eventually react away, largely forming CO2. Perhaps a few million years, and no free oxygen left.