Arecibo Message

In 1974, the most powerful broadcast ever deliberately beamed into space was made from Puerto Rico. The broadcast formed part of the ceremonies held to mark a major upgrade to the Arecibo Radio Telescope.
Space Signal

Humankind just beamed a signal at space aliens. Was that a bad idea?

Trying to find aliens by pinging only one star system is a long shot. But although the broadcast from Norway is unlikely to provoke a response by any Luytenians, you can be sure it will provoke plenty of Earthlings.