Striking Earth

Each day…
• 25 tons of dust and sand-size particles burns up entering the atmosphere.

About once a year…
• A car-size asteroid hits Earth’s atmosphere but typically burns up before reaching the surface.

Every thousand years or so…
• An object the size of a football field hits Earth and causes significant damage to the impact area.

Every few million years…
• If an object larger than 0.6 miles across struck Earth, it could cause mass extinction and threaten civilization.

From a graphic accompanying an article in The Washington Post on scientists keeping a lookout.