Scientists listen out for ET within solar system
They may come in peace, or on a mission to invade Earth...
Either way, the possibility of aliens in our cosmic back yard is no longer being ignored by scientists.
Prompted by the recent discovery of a visiting interstellar asteroid, a team of radio astronomers has for the first time started looking for evidence of ET within the boundaries of the solar system.
It began with speculation, later proved wrong, that the asteroid dubbed 'Oumuamua might be an alien artefact.
Scientists used a radio telescope in the remote outback of Australia to check for intelligent radio signals in the FM frequency range between 72 and 102 megahertz (MHz).
They found nothing, but 'Oumuamua inspired the team to expand the Search for Extra-Terrestrial Intelligence (Seti) much closer to home.
Lead scientist Professor Steven Tingay, from Curtin University, Western Australia, said: "If advanced civilisations do exist elsewhere in our galaxy, we can speculate that they might develop the capability to launch spacecraft over interstellar distances and that these spacecraft may use radio waves to communicate.
"Whilst the possibility of this is extremely low, possibly even zero, as scientists it's important that we avoid complacency and examine observations and evidence without bias.
"'Oumuamua has given us an interesting opportunity to expand the search for extra-terrestrial intelligence from traditional targets such as stars and galaxies to objects that are much closer to Earth.
"This also allows for searches for transmitters that are many orders of magnitude less powerful than those that would be detectable from a planet orbiting even the most nearby stars."
The telescope used to search for nearby alien signals, the Murchison Widefield Array (MWA), consists of thousands of antennas and is located in one of the most radio-quiet regions on the planet.
The scientist looked through all of the MWA's observations from last November, December and early January, when 'Oumuamua was between 95 million and 590 million kilometres from Earth.
The asteroid was first identified in October by scientists from the University of Hawaii.
Its name loosely translates as "a messenger that reaches out from the distant past" in Hawaiian.
At first 'Oumuamua baffled the astronomers because of its unusual trajectory and elongated cigar shape.
Later it was confirmed that the object was a rocky asteroid that may have travelled through interstellar space for millions of years before reaching the solar system.
A paper on the research is reported in the Astrophysical Journal.