Aliens

Is there anyone out there?

What are the chances of finding life deep in the Universe? There's only one way to find out - look for it. Our interest in beings from other planets started well over one hundred years ago with stories like HG Wells' The War of the Worlds that told of an Earth invasion by Martians. Back then some astronomers actually believed there could be intelligent life on Mars.

Today with space probes having set down on the red planet we can be sure that Mars is a pretty lifeless planet, so we must look further out in space for a chance of finding communicating aliens.

Listening for signals is known as SETI: the Search for Extraterrestrial Intelligence, and at present our searches are based on finding deliberately-sent radio signals. Any aliens must be sending out a 'beacon' that says We Are Here! if we have any chance of locating them. Normal radio or television signals that aliens have are just too weak for our radio telescopes to detect at the moment.

There are two major SETI projects on our planet, and tens of others, not all using radio telescopes either. The first big one is Project Phoenix, which is a 'targeted search'. This means it looks at about 1000 target stars the same age and build as our Sun all within 200 light-years of the Earth (one light-year is the distance that light travels in one year). The second big search is Project SERENDIP, which gazes at whatever part of the sky the attached radio dish happens to be looking at. The word 'serendipity' means a happy discovery by accident, which should give you some idea of how they chose the project name - it's just like taking a lucky-dip into the sky.

Some other searches have started looking for laser beams, pulses of light aliens may be sending out. So, there's plenty of activity, but unfortunately we have not one shred of evidence that anyone is out there - yet.