"Extraordinary claims require extraordinary evidence."

Carl Sagan (Cosmos, 1980)

Astronomers will apply this phrase to a signal captured with China's "Sky Eye" telescope that might be a transmission from aliens.

The article about the signal was posted on the website of the Science and Technology Daily newspaper, but was later removed. Astronomers have found evidence of intelligent life outside of Earth. Is it being kept quiet?

We should be interested but not excited. An interesting signal has to go through a lot of tests to find out if it is a sign of extraterrestrial technology or if it is the result of an unexpected source of interference.

Media releases are usually timed for simultaneous release with peer-reviewed results, so it was probably just released a bit early by mistake.

An eye on the sky

Sky Eye is the biggest and most sensitive single-dish radio telescope in the world. The structure is built inside a natural basin in the mountains of China.

The telescope is so large that it can't be tilted, but it can be pointed in a direction that makes it look less reflective. The location of the telescope's focal point can be changed by changing the surface.

FAST can be used for astronomy research in a variety of areas. The search for SETI is one of the areas.

While the telescope is also running its primary science programs, SETI observations are mostly done iniggy-back mode. Large swaths of the sky can be scanned for signs of alien technology without disrupting other science operations. Dedicated SETI observations are still carried out.

The hunt for alien technology

Frank Drake pointed the Tatel telescope towards two nearby Sun-like stars and scanned them for signs of technology in the 1960's.

The searches have become more sensitive over the years. The systems in place at FAST can process billions of times more radio spectrum than Drake could.

We haven't found any evidence of life outside of Earth.

Fast is able to sift through a lot of data. A telescope feeds 38 billion samples a second into a cluster of high- performance computers, which then produce exquisitely detailed charts of incoming radio signals. There are signals that look like technosignatures.

FAST is able to pick up faint signals. The Parkes Radio Observatory's telescope is less sensitive than it is. The output power of a transmitter on a nearby exoplanet could easily be detected by FAST.

The trouble with sensitivity

The problem with being so sensitive is that you can find interference that is too faint to detect. The SETI researchers have had this before.

The signal we called BLC1 was found last year.

It turned out to be weird interference. We had to develop a new verification framework.

It was developed for BLC1 to verify candidate techno signatures. The SETI Institute is named afterSofia Sheikh.

It took about a year for peer-reviewed analysis to be published. We might need to wait a while for the FAST signal to be analyzed.

The chief scientist for the China Extraterrestrial Civilization Research Group acknowledged this.

The possibility that the suspicious signal is some kind of radio interference is also very high, and it needs to be further confirmed and ruled out. This may be a long process.

We might need to get used to a gap between finding signals and getting them verified. Many more signals are likely to be found byFAST and other telescopes.

Some of these may be new astrophysical phenomena and some may be technosignatures.

Stay intrigued

The burden of extraordinary evidence will be met by FAST's extraordinary signals. It's too early to say, but it's encouraging that their SETI searches are finding strange signals.

There is a lot of interest and activity in the SETI field. It's not just radio waves that are being searched.

Stay interested but don't get too excited.

Danny Price is a senior research fellow.

Under a Creative Commons license, this article is re-posted. The original article is worth a read.