The moon is second only to the sun as the most dynamic feature of our sky. It moves across the sky from east to west once every day and each month it goes from being invisible to the brightest object in the night sky and back to invisible again. These patterns result from the motions of the earth, moon and sun relative to each other.
Tuesday, March 29, 2011
Thursday, March 17, 2011
Saturday, March 12, 2011
On Earth, naturally occurring matter exists in one of three phases: solid, liquid or gas. Matter in each phase exhibits distinct characteristics. Gases, for example, do not have a fixed volume or shape. As a result, gases respond to pressure changes by changing their volume. In other words, gases are compressible. In contrast, liquids and solids are not compressible. Their volume does not change in response to changing pressure. This is the reason air filled spaces in our ears “pop” during airplane takeoff and landings while the liquid filled spaces in our bodies do not. Boyle's Law describes this relationship between gas pressure and volume.