![]() ![]() When the receiver reaches a certain position, it might just be able to reflect waves from the ground onto the dish and then back to itself, making it seem as if the signal was coming from space. The Arecibo telescope has a fixed dish reflector and scans the skies by changing the position of its receiver relative to the dish. The signal could be an artefact that, for some reason, always appears to be coming from the same point in the sky. But in the case of SHGb02+14a, every observation has first been made at 1420 megahertz, before it starts drifting. What is more, if telescopes are observing a signal that is drifting in frequency, then each time they look for it they should most likely encounter it at a slightly different frequency. A planet would have to be rotating nearly 40 times faster than Earth to have produced the observed drift a transmitter on Earth would produce a signal with a drift of about 1.5 hertz per second. The relatively rapid drift of the signal is also puzzling for other reasons. “If are so smart, they’ll adjust their signal for their planet’s motion.” The fact that the signal continues to drift after this correction is “fishy”, he says. He points out that the software corrects for any drift in frequency. This does not, however, convince Paul Horowitz, a Harvard University astronomer who looks for alien signals using optical telescopes. “The signal is moving rapidly in frequency and you would expect that to happen if you are looking at a transmitter on a planet that’s rotating very rapidly and where the civilisation is not correcting the transmission for the motion of the planet,” Korpela says. For instance, the signal’s frequency is drifting by between eight to 37 hertz per second. It was Bell Burnell who in 1967 noticed a pulsed radio signal which the research team at the time thought was from extraterrestrials but which turned out to be the first ever sighting of a pulsar. “It may be a natural phenomenon of a previously undreamed-of kind like I stumbled over,” says Jocelyn Bell Burnell of the University of Bath, UK. ![]() That does not mean that only aliens could have produced it. But, Korpela thinks it unlikely SHGb02+14a is the result of any obvious radio interference or noise, and it does not bear the signature of any known astronomical object. The telescope has only observed the signal for about a minute in total, which is not long enough for astronomers to analyse it thoroughly. “This just doesn’t do that, but it could be because it is distant.” Unknown signature “We are looking for something that screams out artificial’,” says UCB researcher Eric Korpela, who completed the analysis of the signal in April. SHGb02+14a seems to be coming from a point between the constellations Pisces and Aries, where there is no obvious star or planetary system within 1000 light years. Some astronomers have argued that extraterrestrials trying to advertise their presence would be likely to transmit at this frequency, and SETI researchers conventionally scan this part of the radio spectrum. This happens to be one of the main frequencies at which hydrogen, the most common element in the universe, readily absorbs and emits energy. Named SHGb02+14a, the signal has a frequency of about 1420 megahertz. “It’s the most interesting signal from says Dan Werthimer, a radio astronomer at the University of California, Berkeley (UCB) and the chief scientist for “We’re not jumping up and down, but we are continuing to observe it.” Or it could be something much more mundane, maybe an artefact of the telescope itself.īut it also happens to be the best candidate yet for a contact by intelligent aliens in the nearly six-year history of the project, which uses programs running as screensavers on millions of personal computers worldwide to sift through signals picked up by the Arecibo telescope. It could be generated by a previously unknown astronomical phenomenon. This radio signal, now seen on three separate occasions, is an enigma. The team has now finished analysing the data, and all the signals seem to have disappeared. ![]() ![]() The same telescope had previously detected unexplained radio signals at least twice from each of these regions, and the astronomers were trying to reconfirm the findings. In February 2003, astronomers involved in the search for extraterrestrial intelligence (SETI) pointed the massive radio telescope in Arecibo, Puerto Rico, at around 200 sections of the sky. ![]()
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