May 25th, 2015
First Quarter Moon

What is dark matter?

The short answer is no one really knows. Dark matter is a name given to something that, so far, has only been detected by the gravitational force that it exerts on visible matter and light. In fact, that gravitational force…


What is the Doppler Effect?

Stand on the sidewalk and listen to the sound of a car as it approaches and passes by. You will notice that the pitch of the sound is higher as the car approaches and then becomes lower as it moves…