35 replies to this topic

[Waspie_Dwarf]

Tau Ceti's planets nearest around single, Sun-like star

www.bbc.co.uk said:

The nearest single Sun-like star to the Earth hosts five planets - one of which is in the "habitable zone" where liquid water can exist, astronomers say.

Tau Ceti's planetary quintet - reported in an online paper that will appear in Astronomy and Astrophysics - was found in existing planet-hunting data.

The study's refined methods of sifting through data should help find even more far-flung worlds.

Read more...

[freetoroam]

"It is also clear that in almost every direction we look and in every way that we look, there are planets around stars near and far."

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it would be more surprising if this were not the case, well for people like myself who truely believe we are not alone.
other planets out there like ours is not a issue, its the communicating with them we have to conquer, unless they were the ones who originally conquered Earth, we just do not remember it!

[bison]

Yes, with planets tentatively detected around the very nearby stars Alpha Centauri, Epsilon Eridani, and now, Tau Ceti, the case for planets being very plentiful is looking better and better.
If planet 'e' of Tau Ceti, which appears to be within that stars habitable zone, is Earth-like in its composition, its 4.3 times Earth mass indicates a planet about 12,000 miles in diameter, half again as large as Earth, with about twice the surface gravity of our planet.
Tau Ceti is thought to be about 5.8 billion years old, somewhat over a billion years older than our Sun.  There has probably been ample time for life to have begun, and to have progressed to well beyond the point that it has on Earth.

Edited by bison, 19 December 2012 - 05:40 PM.

[stevewinn]

I wonder if SETI has been listening in the direction of this star?

[Waspie_Dwarf]

stevewinn, on 19 December 2012 - 06:51 PM, said:

I wonder if SETI has been listening in the direction of this star?

SETI has been listening in pretty much all directions.

I think it is safe to say there is no civilisation with similar technology to ours on the planets around Tau Ceti. At 12 ly distance if there was a civilisation using radio technology then the Tau Ceti system would be one of the brightest objects in the sky in radio frequencies, it isn't. Of course a civilisation just 2 centuries behind us in technological capability would not yet have radio capability.

This doesn't exclude a civilisation more advanced than use using communications methods we haven't even thought of yet, but if that is the case it would seem likely to me that they don't want to communicate with us. Any advanced civilisation in the Tau Ceti system would have been aware of our existence for almost exactly a century.

The fact that we aren't already aware of an advance civilisation at Tau Ceti would seem to me that either they don't want to communicate with us or they simply aren't there.

Still with an estimated 500 million planets in the habitable zone in this galaxy alone there are plenty more places to look.

[Waspie_Dwarf]

A quick bit of research shows that Tau Ceti was one of the earliest targets for SETI.

From this Universe Today article: Five Planets Around Nearby Star Tau Ceti; One in Habitable Zone:

Quote

During the 1960′s, Project Ozma, led by SETI’s Frank Drake, probed Tau Ceti for signs of life by studying interstellar radio waves with the Green Bank radio telescope.

This is what Wikipedia has to say about Project Ozma:

Quote

Drake used a radio telescope with a diameter of 85 feet (26 metres) to examine the stars Tau Ceti and Epsilon Eridani near the 1.420 gigahertz marker frequency. Both are nearby Sun-like stars that then seemed reasonably likely to have inhabited planets. A 400 kilohertz band was scanned around the marker frequency, using a single-channel receiver with a bandwidth of 100 hertz. The information was stored on tape for off-line analysis. Some 150 hours of intermittent observation during a four-month period detected no recognizable signals. A false signal was detected on April 8, 1960, but it was determined to have originated from a high-flying aircraft.

Source: Wikipedia

[bison]

stevewinn, on 19 December 2012 - 06:51 PM, said:

I wonder if SETI has been listening in the direction of this star?

THE SETI Institute currently listens to a list of stars found to have planets, including those turned up recently by the Kepler Space Telescope. They will probably now add Tau Ceti to this list,  It is visible from mid-Northern latitudes, though always rather low in the sky. The 'V' formed by the horns of Taurus make an arrow that points to it, about 40 degrees away. Tau Ceti is due South at about 9:30 in the evening, at this time of year.

Edited by bison, 19 December 2012 - 07:35 PM.

[Waspie_Dwarf]

bison, on 19 December 2012 - 07:33 PM, said:

They will probably now add Tau Ceti to this list,

They won't need to, this article SETI embarks on biggest-ever search for extraterrestrials from  November 2010 suggests that Tau Ceti has been a SETI target long before this discovery:

Quote

The Search for Extraterrestrial Intelligence (SETI) is turning its focus once again on some of the stars that were its very first targets back in 1960.

For the last week, astronomers around the world have been looking out for radio and laser signals from civilizations circling stars including Tau Ceti and Epsilon Eridani.

[bison]

I wouldn't assume that there is a technical civilization on Tau Ceti  e, simply because there *could* be. Nor would I assume that there isn't one, simply because we haven't managed to hear from them yet. We may not have listened with sufficient sensitivity, at the correct frequency, and at the correct time. Further radio scrutiny, such as the discovery of a potentially habitable planet, and one so close by, might bring, may yet turn up something.
I don't think that we need assume that a nearby civilization in space is wholly uncommunicative, simply because they haven't mounted an effort to be heard by us, at an arbitrary level of obviousness. Perhaps were not at the top of their list of priorities, or perhaps, knowing something of us from our broadcasts, they make themselves heard to a sufficient level of technical development, which they hoped will also a certain social maturity, as well.

[Waspie_Dwarf]

bison, on 19 December 2012 - 08:12 PM, said:

We may not have listened with sufficient sensitivity, at the correct frequency, and at the correct time.

This assumes that the ONLY communications they are making are attempts to communicate with us. That is possible but would seem highly unlikely to me. We don't need to send a signal to any stars within around 100 light years because they would already know we are here. Transatlantic radio signals started in 1901, since the numerous radio stations, tv stations, over the horizon radar have all been transmitting and the signals leaking into space. Earth is now one of (if not the) brightest radio source in the sky for tens of light years in all directions. Earth is a million times brighter than the sun in radio frequencies. A comparable civilisation to ours using comparable technology as close as 12 light years should stand out like a sore thumb, even if they aren't deliberately trying to communicate with us.

I stand by my conclusions.

[bison]

Waspie_Dwarf, on 19 December 2012 - 07:52 PM, said:

They won't need to, this article SETI embarks on biggest-ever search for extraterrestrials from  November 2010 suggests that Tau Ceti has been a SETI target long before this discovery:

       You're referring to Project Dorothy, which was intended to commemorate the 50th anniversary of Project Ozma. Various observatories listened briefly at various frequencies, and with various levels of sensitivity at a list of target stars which included Tau Ceti. The SETI institute, to which I had reference, listened from November 5th through 7th, in 2010,  at frequencies immediately surrounding 1420 MHz. I would hope they would consider a more sustained and widespread effort, in light of this new discovery at Tau Ceti.

[spud the mackem]

Radio/Electricity was only discovered by us recently in the time range of things, so we are "infants" in the use of this technology. However if there is Alien life on this planet,they could be 1000's of years ahead or behind us,in which case they are using far more advanced systems of communication,or they havent yet discovered it.We cannot think that we are are the most civilised advanced form of life in the universe,because we aren't that civilised, or that far advanced in technology. I would like to believe that we aren't alone as a life form,but there could be 1000's of different life forms not even carbon based, so we wouldn't necessarily recognise a new life form if it was based on silicone for example, or some compound base that we haven't even thought of.

[stevewinn]

its all very interesting thanks for the replies Waspie & Bison. when it comes to SETI, do they use more advanced methods of listening today than back when they first started? or last listened into Tau Cet star system?

[AsteroidX]

This will require a recalibration of the Drake equation perhaps

I believe SETI has done some refinement of there listening. But I have also heard criticicism of there methods. A poorly funded project that has managed to survive some lean years.

Edited by AsteroidX, 19 December 2012 - 09:07 PM.

[bison]

Waspie_Dwarf, on 19 December 2012 - 08:28 PM, said:

This assumes that the ONLY communications they are making are attempts to communicate with us. That is possible but would seem highly unlikely to me. We don't need to send a signal to any stars within around 100 light years because they would already know we are here. Transatlantic radio signals started in 1901, since the numerous radio stations, tv stations, over the horizon radar have all been transmitting and the signals leaking into space. Earth is now one of (if not the) brightest radio source in the sky for tens of light years in all directions. Earth is a million times brighter than the sun in radio frequencies. A comparable civilisation to ours using comparable technology as close as 12 light years should stand out like a sore thumb, even if they aren't deliberately trying to communicate with us. I stand by my conclusions.

           I don't assume that a technical civilization must be leaking radio frequency energy into space to anywhere near the same extent that we do. It is entirely possible that communication cables and narrow beam, relatively low power signals from and to relay satellites, and other technical developments will eventually make a civilization inconspicuous in the radio range. We have no grounds for assuming that another civilization will just happen to be at a level of development so similar to our own that we can use ourselves as an example of what they would be doing.
Such a civilization might have a radio beacon operating for the benefit of species at about our level of development, but still might not wish to make it too easy for us to receive it.  For example, it might transmit only briefly and infrequently. Perhaps they wish to reward patience, and communicate with those who have learned to exercise this trait.