In the Cold War summer of 1947, flying-saucer mania gripped the United States. The phrase “flying saucer” entered the lexicon in June, when a pilot reported seeing several of them near Seattle. Over the following six weeks, thousands of sightings were reported. And 75 years ago this week, the Army announced it had recovered a saucer that crashed near Roswell, New Mexico.

It’s unlikely that alien spacecraft visited Earth in 1947 or any other year, though. Traveling between the stars isn’t like the movies — you can’t just whoosh from star to star.

The closest star to the Sun is Proxima Centauri, four and a quarter light-years away. The light that leaves Proxima Centauri tonight — traveling at 670 million miles per hour — won’t reach Earth until 2026. And the speed of light is the universal speed limit — nothing in the “normal” universe can go faster.

The laws of physics do allow some shortcuts to the stars. But most of them require huge amounts of energy, they need exotic forms of matter, or they face other obstacles. Engineers have tinkered with some ideas for interstellar ships, but the craft tend to be ponderous, not jaunty little saucers.

A team is working on a way to send an entire fleet of ships to Proxima Centauri. Lasers on Earth would zap “sails” on the ships, pushing them outward at up to 20 percent of the speed of light. There’s only one drawback: Each ship would be about the size of a postage stamp.
 

Script by Damond Benningfield

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