How do Alzheimers start?

In people with early-onset Alzheimer's, a genetic mutation may be the cause. Late-onset Alzheimer's arises from a complex series of brain change...

How old is Punxsutawney Phil?

HOW OLD IS PHIL? According to Groundhog Club members, there has only been one Phil — and he has been predicting since 1887. That makes him 135 years old! ...

Is the sky really blue?

Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it tra...