Perihelion Countdown

The Earth is heading for its closest approach to the Sun, which will take place on January 4th. We will be about 3 million miles closer to the Sun then than at Aphelion on July 5th. This change in distance does not cause the seasons but it does affect the length of the seasons! Due to the fact that the Earth is moving more quickly along its elliptical orbit when closer to the Sun than when further away, winter in the Northern Hemisphere is shorter than Summer - hooray! It takes 5 days less to move from the September equinox to the June solstice than vice versa.
The varying distance does make a difference to how large the Sun's disc appears however. I took a shot on July 5th this year and skies being clear I will take one on January 4th and montage them to compare the angular size.
Talking of elliptical orbits, it is Kepler's 442nd birthday today, the towering genius who calculated his 3 laws of planetary motion. It cannot be stressed too much just how important he is!