We know that asteroids have hit Earth in the past, and there are thousands of potential asteroids that can hit Earth in the future. Many of these asteroids are still unknown to us, as described here:
Given the threat, it seems prudent for humans to have a strategy and a system in place to guard against rogue asteroids.
“The Doomsday Book” by Marshall Brain lays out this scenario in amazing detail and offers solutions to prevent this doomsday scenario from unfolding. You can order the book today on Amazon and other retailers.