When the sun is closest to Illinois

Dear Tom,
When is the sun the closest to Illinois? I have a bet with my husband and he
believes everything you say!
Cheryl Hanson
Dear Cheryl,
The Earth completes an orbit of the sun in approximately 365.24 days, but
the path is not perfectly circular. Rather, it's an ellipse -- a slightly
flattened circle -- and the sun is not quite in the center of the elliptical
area. The Earth (and Illinois) is consequently closest to the sun when it
travels through the "end point" of its elliptical path that lies nearest the
sun; it is farthest from the sun at the opposite "end" of the ellipse.
Those points are known as perihelion (closest to the sun) and aphelion
(farthest). Perihelion and aphelion dates vary by a few days from year to
year, but in 2009 perihelion (91.7 million miles) occurred at 9 a.m. CST on
Jan. 4 and aphelion (94.8 million miles) will occur at 9 p.m. CDT on July 3.