Facebook CEO Mark Zuckerberg will also join Milner and Hawking on the board of Breakthrough Starshot, a philanthropic initiative to focus on space exploration and the search for life in the universe.

Astronomers believe an Earth-like planet could exist within the "habitable zones" of Alpha Centauri, the closest star system to Earth, located 25 trillion miles (or 4.37 light-years) away.

Breakthrough Starshot hopes to launch thousands of the tiny, light-propelled spacecraft -- called nanocrafts -- with the goal of reaching the star system in twenty years.

Each nanocraft is designed to fly at twenty percent the speed of light, on a sail pushed by a light beam, making it over a thousand times faster than today's fastest spacecraft. With conventional spacecraft technology, it would take 30,000 years to reach Alpha Centauri.

"Earth is a wonderful place, but it might not last forever," Hawking said in a statement. "Sooner or later, we must look to the stars. Breakthrough Starshot is a very exciting first step on that journey."