Back in April, Russian billionaire Yuri Milner pledged US$100 million toward a crazy plan to visit another star system.

The mission — Breakthrough Starshot — aims to get this done by propelling teeny, tiny spaceships to 20 percent the speed of light with powerful lasers.

Milner and famed physicist Stephen Hawking initially said their destination would be Alpha Centauri: a star system located some 4.37 light-years (25.7 trillion miles) away from Earth.

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