If you ever thought what happens on Earth stays on Earth, think again. Astronomers have now reported that we are sending more signals into space than we know, and we might not be the only ones in the Universe listening in.
PhD researcher Mr Ben McKinley from the ANU Research School of Astronomy and Astrophysics calculated the strength of the Earth’s radio signals, and found that listening in on us would be feasible, provided an alien civilisation had far superior technologies to our own.
But if others could eavesdrop, the information would be out of date as our nearest neighbour, Proxima Centauri, is approximately four light years away from Earth.
Mr McKinley worked with other astronomers from the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) using the Murchison Widefield Array (MWA) in Western Australia – one of three precursor instruments to Square Kilometre Array. They found that the Moon reflects signals from our TV and radio stations in the FM band (87.5 – 108.0 MHz).
“The Moon is of course a well-known celestial object to everyone on Earth, especially astronomers, so we were looking at it to see if we could use it as a stable and predictable way to calibrate our telescopes,” said Mr McKinley.
“What we actually found was that the moon is reflecting every breaking news story, Top 10 hit, football score, press conference and soap opera, mixed together in a noisy echo of all the Earth’s FM radio signals played simultaneously.”
The MWA telescope is highly sensitive to radio frequencies in the 80-300 MHz range and has been designed to search for the very faint signals from the formation of the first stars in the early Universe. To avoid man-made radio frequency interference from nearby radio and TV stations, the MWA is located in the outback of Western Australia, at CSIRO’s Murchison Radio-astronomy Observatory.
Mr McKinley’s findings are published in The Astronomical Journal 145, 23 (January 2013) http://m.iopscience.iop.org/1538-3881/145/1/23/
This project is part of ‘The Evolving Universe’ theme of CAASTRO (www.caastro.org).