Date: 10/06/2017 13:08:39
From: Tau.Neutrino
ID: 1077324
Subject: Wow! mystery signal from space finally explained
Fair enough.
Date: 13/06/2017 20:13:51
From: mollwollfumble
ID: 1078329
Subject: re: Wow! mystery signal from space finally explained
On the topic of SETI, I have become an enormous cynic. Hence my delay in posting to this thread, I had to wait for my cynicism to wane.
But on this occasion, I have to applaud heartily and thoroughly.
For starters, I know that the frequency that was used for detecting the Wow! signal is generated by neutral hydrogen, and I also (on reflection) agree that the water vapour seen shooting from comets is split into hydrogen and oxygen by the Sun’s UV light.
I would even go further. SETI@home has recorded tens of thousands of other signals like the Wow! signal. I would dearly like to know how many of them could have been generated by a comet. There is also one other old SETI candidate that could potentially have a similar explanation – if a periodic comet was found to match the observed signal periodicity.
Why wasn’t this explanation seen decades ago ago? Or was it? Reading in the link below, it had been considered before but rejected because a comet at that distance from the Sun should not have been active enough to generate a signal that large. It was only on looking at one of the two possible comets 266P again at the same distance from the Sun that it was confirmed.
This link is also worth following https://phys.org/news/2016-04-famous-radio-telescope-comets.html#nRlv because it’s the most complete description of the science behind the Wow! signal that I’ve ever seen. Including an aerial photo of the radio telescope that detected the signal. It’s not like any other radio telescope I’ve ever seen. The signal itself is Gaussian, which I’d suspected but had never seen proved.
“Big Ear listened for just 72 seconds before Earth’s rotation carried the signal’s location out of “view” of antenna. Since the radio array had two feed horns, the transmission was expected to appear three minutes apart in each of the horns, but only a single one ever picked it up. Despite follow-up observations by Ehman and others (more than 100 studies were made of the region) the signal was gone. Never heard from again.”
“A quick check on 266P and 335P at the time of the signal show them both around 5 a.u. from the sun (Jupiter’s distance) and extremely faint at magnitudes 22 and 27 respectively. Were they even active enough at those distances to form clouds big enough for the antenna to detect? Paris knows there’s only one way to find out. Comet 266P/Christensen will swing through the same area again on Jan. 25, 2017, while 335P/Gibbs follows suit on January 7, 2018. Unable to use an existing radio telescope (they’re all booked up!), he’s begun a gofundme campaign to purchase and install a 3-meter radio telescope to track and analyze the spectra of these two comets.”
Technical paper at http://planetary-science.org/wp-content/uploads/2017/06/Paris_WAS_103_02.pdf
See Figures 11 and 12 for Gaussian signals at the same comet. Because a comet is asymmetric, the signal isn’t always gaussian. The field of view is smaller here than for the original Wow! signal, so the durations are also shorter, 10 to 20 seconds. Up to an 13.4 dB gain in signal was detected, but how does that compare with the strength of the Wow! signal? Does that ‘U’ in the Wow! signal correspond to a 30 dB gain? If so, we’re in the right ballpark.
I’m satisfied with this explanation, or I would be if it is checked against a large number of other Wow!-like signals detected by SETI@home.
