E.T.s may be headed toward Earth, but are we ready for them?

Twenty years from now we might get a call from aliens. In 2017, a powerful radio transmission was aimed at exoplanet GJ 273b, thought to be able to support life. Its message, sent by the alien-hunting group Messaging Extraterrestrial Intelligence International, contained instructions on how to understand Earthling math, music and time. If it lands on intelligent alien ears once it arrives in about a decade, E.T. now has our number.