BBC Sky at Night Magazine on MSN
Aliens could detect our airports. Scientists say radar signals could reveal our presence across the galaxy
Planet Earth could be giving out its own signals, which could in turn be detected by distant astronomers on an alien planet ...
The Great Filter theory suggests advanced civilisations may self-destruct before contacting others, explaining the universe's ...
Some results have been hidden because they may be inaccessible to you
Show inaccessible results