A group of scientists has revealed they have sent a detailed message to a nearby planet in the hope of contacting alien life – and hope to send another soon.

The project, called Sónar Calling GJ273b, was led by the Sónar organization, who sought the help of METI International (Messaging Extraterrestrial Intelligence) and The Institute of Space Studies of Catalonia (IEEC).

On October 16, 17, and 18 of this year, the group sent a batch of transmissions using the EISCAT (European Incoherent SCATter Scientific Association) antenna in Tromsø, Norway. Those transmissions have been announced for the first time today.

The messages were sent to the exoplanet GJ 273b, a super-Earth about 2.9 times the size of our planet that orbits in its star’s habitable zone. The star is known as Luyten’s Star, or GJ 273, a red dwarf located about 12.4 light-years from Earth. If there's anyone there, we could expect a reply in about 25 years.

"We selected Luyten’s star, also known as GJ273, because it’s the closest star that’s visible from the northern hemisphere that is known to have a potentially habitable exoplanet in orbit," Douglas Vakoch, President of METI, told IFLScience.

These are the first interstellar messages ever sent by METI, but today’s announcement comes on an important anniversary. Forty-three years ago, the famous Arecibo Message was sent towards the globular cluster M13, 25,000 light-years from Earth, in the hopes of making contact. A reply from any planets there would take 50,000 years – so this latest initiative aims to speed things up a bit.

The project is a bit of an odd marriage in truth between a music festival and an organization that is actively trying to make contact with life in the universe. But there is some science behind it, as the message contains useful tidbits about Earth that would help any intelligent aliens on this planet discern that we exist.

"This project tests the Zoo Hypothesis, which says that perhaps extraterrestrial civilizations are much closer than we’d imagined, perhaps even around the nearest stars, but they’re watching us like we watch animals in the zoo," said Vakoch.

"In the more realistic scenario that intelligent life is rare in the galaxy, we may need to signal a thousand or a million stars before we get a response."

^{An example of some of the content that might be in the second message}

The message includes 33 musical pieces, each lasting 10 seconds long, that were commissioned for the project. It also contains a mathematical and scientific tutorial created by METI that starts with basic principles and builds up to more complex concepts, to show our intelligence.

For example, it describes the key characteristics of electromagnetic waves, by pointing to the frequency and direction of radio waves. The message was transmitted nine times over three days, which means that any aliens who happen to be listening have time to confirm that the signal is coming from our planet.

The scientific part of the message also contains a “cosmic clock” that tracked the passage of time over the three days of transmissions. The goal of this is to show the aliens how we measure time, and help any potential observers work out that we're real.

"If an astronomer on GJ273b detects our signal, they’ll need to follow-up to confirm it’s artificial, and not created by nature," said Vakoch. "We transmitted our message on three successive days, giving extraterrestrials an opportunity for repeated observations."

In April 2018, the plan is to send another message to the star, with even more information about our scientific understanding. This second message will end with a clock time, which will tell the aliens that we are expecting to hear a reply from them in 25 years – roughly the time for a round-trip of communications – on June 21, 2043.

Whether anyone is out there, let alone on this specific planet, well that’s anyone’s guess. But projects like these always instill a bit of public excitement as a talking point at the very least. And you never know, we may just get the reply we’re hoping for.