Why is a big asteroid next predicted to hit earth?
There are currently no asteroids that are predicted to hit the Earth. Nothing in the sky that is big enough to be visible is likely to hit us.
However, astronomers frequently discover nearby objects that are very close indeed. in fact, last October, astronomers located a fairly small asteroid on a collision course with Earth - only 18 hours before it hit. That asteroid, a fairly small object about the size of a small house, exploded over the Sudan without causing any known damage or injury.
And last month, astronomers discovered an asteroid that's in a "co-orbit" with the Earth, never very far away and moving in pretty much the same direction.
The nearest thing to a "prediction" is the asteroid Apophis, which will come very close to Earth on Friday, April 13, 2029, and again on Friday, April 13, 2036. However, further analysis of the orbit of Apophis indicates that there is only one chance in 40,000 that it will hit.