Researchers at the University of California recently traced the paths of radio wave transmissions from Earth to the most distant probes. With this tracing, they determined which stars or planets, with the possible alien life around them, are in the best position to intercept any possible messages from extraterrestrial life.

The researchers created a list of the stars that will encounter the Earth’s signals within the next century.

They found that any possible extraterrestrial civilisations could send a message back to Earth as soon as 2029. NASA sent a signal back in 2002 to Pioneer 10. It reached a dead white dwarf star, roughly 27 light-years from Earth.

In the study published in the Publications of the Astronomical Society of the Pacific, a return message from any possible aliens living near this dead star is estimated to reach us by 2029.

Other possible return messages could come from the Voyager 2, which had signals over 40 years ago. This means if any aliens sent a message straight back when they received the signal in 2007, we would receive their reply in the early 2030s.

Lead author and engineering student at the University of California told PopSci that this work “gives Search for Extraterrestrial Intelligence researchers a more narrow group of stars to focus on.”

However, astronomers are worried that if a response were to be sent, we might be unable to detect it.

Astronomer Macy Huston told PopSci, “If a response were to be sent, our ability to detect it would depend on many factors.” The factors would include “how long or often we monitor the star for a response, and how long or often the return signal is transmitted.”