If aliens exist they could already be watching
Once, in a galaxy far, far away, an alien race may have been watching and listening to humans on Earth, a study has claimed.
The findings state there are 29 planets that are “potentially habitable” — and therefore may harbour life — and are close enough to our planet to have received human radio waves. The researchers were unable to prove that aliens did spy on humans, or indeed if aliens exist at all, but they sought to find out whether it was possible that we were being watched by beings on another planet.
Astronomers from Cornell University set out some simple criteria to do so.
First, the distant planets must be deemed “potentially habitable”; second, they must be within range.
To meet the first aspect, researchers looked for planets that had been observed passing in front of their star, and then assumed that about a quarter of these are rocky worlds. It is believed that it is essential for a planet to be rocky for life to exist, and a gaseous planet could not sustain life.
Next, the results were narrowed to determine how close the planets were to Earth and if this was near enough to detect human activity.
Human beings have existed for more than 300,000 years, but only formed large, complex civilizations about 5,000 years ago.
As a result, alien astronomers would need to be within 5,000 light years of the Earth to have a realistic chance of seeing human activity en masse because light from Earth, which travels at the speed of light, needs to reach them.
The researchers found 1,715 stars within this range but say that the radius will continue to grow, and in another 5,000 years it will include a further 319 stars.
Of the 1,715 stars within the 5,000-year range, only 75 were found to be within 100 light years of our home world. This makes these planets close enough to pick up radio waves from Earth.
Of the 75 stars in this 100-year range, seven are known to have rocky planets orbiting them. In these seven star systems, there are 29 planets that could host life.