The telescope has only observed the signal for about a minute in total, which is not long enough for astronomers to analyse it thoroughly. 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.
That does not mean that only aliens could have produced it. â€œIt may be a natural phenomenon of a previously undreamed-of kind like I stumbled over,â€ says Jocelyn Bell Burnell of the University of Bath, UK.
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.
There are other oddities. For instance, the signalâ€™s frequency is drifting by between eight to 37 hertz per second. â€œThe signal is moving rapidly in frequency and you would expect that to happen if you are looking at a transmitter on a planet thatâ€™s rotating very rapidly and where the civilisation is not correcting the transmission for the motion of the planet,â€ Korpela says.
This does not, however, convince Paul Horowitz, a Harvard University astronomer who looks for alien signals using optical telescopes. He points out that the SETI@home software corrects for any drift in frequency.
The fact that the signal continues to drift after this correction is â€œfishyâ€, he says. â€œIf [the aliens] are so smart, theyâ€™ll adjust their signal for their planetâ€™s motion.â€
The relatively rapid drift of the signal is also puzzling for other reasons. 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.
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. But in the case of SHGb02+14a, every observation has first been made at 1420 megahertz, before it starts drifting. â€œIt just boggles my mind,â€ Korpela says.