Kuiper Belt Objects Are as Mysterious as They Are Distant

Recently the New Horizons spacecraft made the first flyby of a Kuiper Belt Object (KBO) in the extreme outer solar system. What do we know about KBOs?
A meteor striking earth

How to Avoid a Meteor

It isn’t likely that Earth will be hit by a large meteor, but if it were, the results would be catastrophic.
Hevelius map

Where Did the Moon Come From?

Despite years of study, it is only since the 1980s that a theory of the moon's origin has coalesced.
Tyrannosaurus rex skeleton (the specimen AMNH 5027) at American Museum of Natural History.

An Asteroid Killed the Dinosaurs. Right?

What killed the dinosaurs? An asteroid wiped them out, right? New research suggests that even before that cataclysm, dinosaurs weren't doing so well.