If the projectiles are relativistic, then warning could only be a few days or ev...

		stcredzero on April 25, 2010 \| parent \| context \| favorite \| on: Don’t talk to aliens, warns Stephen Hawking If the projectiles are relativistic, then warning could only be a few days or even a few hours ahead of time. Even relativistic impactors are unnecessary. Low albedo impactors coming in from angles far off the ecliptic would be exceedingly hard to spot.