Small asteroids can be hard to spot. But what kind of threat do they pose to the Earth?
The race may be on to send humans to live on Mars, but is it worth the effort -- and the spend -- when we have our own problems to deal with on Earth.
The mass extinction of the dinosaurs was down to the location of the asteroid's impact and the kind of rocks it landed on.
As much as one-third of animal species in the tropics could be eradicated if their habitats continue to be converted for monoculture farming. We can all do something to make a difference.