We could build a galactic internet but it may take 300,000 years

If there are advanced alien civilizations in the Milky

Way, we ought to be thinking about how to say hello to our neighbours. The vast space between stars makes that difficult, but a fresh simulation suggests that using the sun as a lighthouse beacon could make a galactic community possible.

In the same way that plane and train operators use flashing lights as signals, we could one day manipulate the light shining from our sun, like waving a hand in front of a torch to shine out a message.

One way to do that is to lasso huge swathes of asteroids or mine a chunk out of Mercury to build a planet-sized sheet to orbit our sun. Another, more feasible, idea is to use powerful lasers to change how Earth’s transits look to other worlds, adding a message encoded in light to our planet’s shadow as it passes in front of the sun.