[Physicist]

The key words are "early enough". A child's sneeze would be sufficient to deflect a doomsday asteroid...if applied "early enough".

I seem to remember reading that attaching a solar sail to an asteroid would actually be a more effective means of deflection.

[AndrewC]

I seem to remember reading that attaching a solar sail to an asteroid would actually be a more effective means of deflection.

An asymmetric assembly of bovine creatures facing in the same direction should prove adequate to the task.