Not all planets orbit stars. Rogues float through the galaxy in darkness and are almost impossible to see.
High speeds, the threat of dangerous crashes, the excitement of the crowd – and the laws of physics on full display. A physicist explains the science of NASCAR.
In science, the word 'theory' has a very specific meaning that's easy for nonscientists to misunderstand or misconstrue. Here's what a theory must withstand to be accepted by the scientific community.