Republish this content
You must give appropriate credit. We ask you to do this by:
1) Using the original journalist's byline
2) Linking back to our original story
See our full republication guidelines here
HTML for this article, including the attribution and page view counter, is below:
How do we know if an asteroid headed our way is dangerous?In our solar system there are millions of space rocks known as asteroids. Ranging in size from a few metres to hundreds of kilometres, these objects are mostly left over from the formation of our planets 4.6 billion years ago. They are building blocks that didn’t quite make it into fully fledged worlds.