Today Is..International Asteroid Day

In memory of the largest Asteroid to break through the Earth's atmosphere in modern times over Tunguska in Russia in 1908, today is National Asteroid Day and the United Nations celebrated it by naming four Asteroids careening towards Earth because nothing allays fears of the human race being extinguished like giving us the dates when it might happen.
First up is 1979 XB, almost five times larger than the 190 meter wide Tunguska Asteroid, currently hurtling through the solar system at nearly 70,000kph and current projections have it approaching close to Earth in 2024.
If 1979 XB misses us we only have to wait another five years for the next apocalypse because the 370 meter Apophis is blazing past our planet in 2029 less than a tenth of the distance to the Moon.
The 50 meter 2000 SG344 is predicted to turn up in our skies between 2039 and 2049 and next up is 2010 RF12 which is top of the ESA danger list travelling at a speed of 117,935kph but luckily is only 7 meters across and although it will have devastating consequences if it hits a major city when it comes in 2090, it is expected to be crushed by the Earth's atmosphere before it reaches the ground, they hope anyway.
Of course any change in the trajectory of any of the Asteroids will send them pinging off away from us still, the United Nations and people in white with telescopes are on it so nothing to worry about and they are actually planning to redirect an Asteroid into orbit around the moon.
Over the past nine years NASA have whittled down the list to just a potential four and are currently looking at which of these have the best velocity, orbit, size and spin to safely deflect our way because if you are going to fling a massive space boulder our way you need to be sure it doesn't go wrong and you find yourself apologising in to the massive crater where Norway used to be. 
With the date for the flinging pencilled in for 2025, NASA have already done a small scale practise by deflecting an Asteroid out of it's orbit which has the double mission of being handy for redirecting the path of an Asteroid or Comet which is dangerously heading our way. 
Called the Double Asteroid Redirection Test (DART), the target was the 170 metre Dimorphos Asteroid about 7 million miles away which found a spacecraft ramming into it at 15,000 mph to change its orbit and provide vital information on how to best to apply it to future planetary defense scenarios which is crucial because an Asteroid over 140 meters landing on Earth would be catastrophic for life on Earth and each year a dozen or so over that size cause some sweating at NASA headquarters.
So yes, while preventing human's being wiped out is very important, it is a large step towards us having an freaking pet Asteroid circling the Moon in one of the coolest astronomical ideas ever.