A project which aims to send nano rockets into space to explore galaxies far beyond Earth, has been announced by Facebook founder Mark Zuckerberg and leading scientist Professor Stephen Hawking.

The $100m (£70m) 'Breakthrough Starshot' project plans to send the small spacecrafts to the Alpha Centauri star system which is 25 trillion million miles or 4.37 light years away.

It is believed that there may be a planet similar to Earth in the far away star system's "habitable zones".

It would normally take 30,000 years to reach Alpha Centauri but it is hoped that by using nano technology the time will be cut to 20 years.

Each 'nanocraft' will be powered by a sail pushed by a light beam, they weigh far less than an ounce and travel at a fifth of the speed of light.

The technology, which is also supported by Silicon Valley philanthropist Yuri Milner, is expected to capture images of possible planets and other scientific data and send the information back to Earth.

Mr Milner told a press conference: "If this mission comes to fruition it will tell us as much about ourselves as about Alpha Centauri.

"Only by challenging ourselves can we find out if we, like the pioneers before us, have the ability and the ambition to succeed. For the first time in human history we can do more than just gaze at the stars, we can actually reach them. It is time to launch the next great leap in human history."

During the launch for the project Professor Hawking said: "I believe what makes us unique is transcending our limits....

"Today we commit to this next great leap into the cosmos because we are human and our nature is to fly."