SUNRISE, SUNSET

Even though we're more than a week past the winter 
solstice, the sunrise has continued to advance later.  It will be two 
weeks before it finally turns the corner and begins rising earlier in 
the morning.  By the end of January, most of us will be getting another 
two minutes of daylength each day (less in Hawaii and the far south, and 
more up  in Alaska and other northern areas..
 
Why does this happen?  It has to do with the shape of the earth, the 
tilt of the earth's axis and the irregularities of our orbit around the 
sun.  If you're interested in sunrise/sunset times,  and how they change 
for anywhere in the country, I suggest you pay a visit to the U.S. Naval 
Observatory website.
 
http://www.usno.navy.mil/USNO/astronomical-applications
 
They also specialize in such obscure but critically important 
information such as twilight -- the amount of light visible before 
sunrise and after sunset.