Since January 8th, we observed four Asteroids whip by Earth.
Anything fly by closer than the moons orbit, especially four in a row in less than a month is enough to at the very least, raise eyebrows.
They are called Near Earth Objects (NEOs)
Had any of these rocks hit the Earth, it would be not have been a global killer, but could levelled a city like a nuclear bomb.
Even if we did have advanced warning, what could we do?