If an asteroid really was on a collision course with Earth, blowing it up wouldn't do much good because the chunks would still have the same momentum. So what do you do? "How I Saved The World" has the answer.
The story, by Bulgarian author Valentin Ivanov, appeared in Mike Brotherton's online anthology of astronomy-based SF, Diamonds In The Sky. Translated into English, it has a wry, sad-sack humor, especially in the final little twist. But mostly, it's worth reading for the clever method for deflecting a destructive asteroid that's due to cause an "extinction-level event" on Earth in 30 years. It's not quite as glamorous as Bruce Willis hauling nukes out onto the asteroid's surface, but it's a lot more scientifically plausible. It involves using the Yarkovsky effect, and a whole lot of black paint.
Also, you can read Ivanov's recently published history of Bulgarian science-fiction here.