Happy Perihelion Day 2011!
What is Parihelion? It is the point in the Earth’s orbit where we are as close to the sun as we can possibly be, and it happens about this time every year. The Bad Astronomy blog has a terrific explanation of parihelion (from an actual astronomer, no less) so I’ll refer you over there for details.
One note: at one point in his post, Dr. Plait advises that the difference in size of the solar disk between parihelion and aphelion can only be appreciated with a telescope. I’ll add that YOU SHOULD NEVER, EVER, EVER look directly at the sun with a telescope, binoculars or your naked eyes!! EVER!! You can cause serious permanent damage to your retinas. There are safe ways to observe the sun for yourself, including pinhole cameras and special telescope filters that can be used with care. Or you can check out the gorgeous pictures from NASA’s nine month old Solar Dynamics Observatory. Super fun and really safe.