
Paintballs Clarify What Happens When an Asteroid Hits Earth’s Ocean
Coastal waves from mid-sized asteroid impacts might be more like a storm surge than a wall of watery destruction, according to NASA experiments with paintballs.
If asteroid 99942 Apophis ever strikes Earth, how big would the crater be?
If the near-Earth asteroid 99942 Apophis ever strikes Earth, how big would the crater be? Apophis (formerly 2004 MN4) ranks at the top of the worrisome-asteroid list. On April 13, 2029 (yes, that will be a Friday the 13th), it will pass only 30,000 kilometers (18,600 miles) from Earth’s surface…

What is the most distant human-caused event that’s been easily verifiable with ordinary optics?
Like other amateurs, I observed the brightening of Comet Tempel 1 after it was hit by Deep Impact on July 4, 2005. Was this the most distant human-caused event that’s been easily verifiable with ordinary optics? (I used my 12-inch Dobsonian reflector.) Yes, we think so. The Deep Impact collision…

Will asteroid 99942 Apophis eclipse the Moon when it passes by?
When I heard that a 300-meter asteroid will approach Earth at a distance of only 18,000 miles in 2029, I figured it was time to break out the old slide rule. Wouldn't an object that big and close be able to eclipse the Moon, if it should pass in front…