Even though the coldest air of the season is poised to reach southwestern Connecticut by the middle of this week, the early Winter is the time of the year when the Earth is nearest to the Sun. In fact, this morning at 6:36 EST, the Earth was closer to the Sun than at any other time in 2015. This is when the Earth is at perihelion.
Since last July, the Earth has been falling ever closer to the Sun. Every moment since then, our planet has edged closer to the nearest star in the universe. The Earth’s orbit around the Sun is not a perfect circle. It’s actually an ellipse, so sometimes we’re closer to the Sun, and sometimes farther away. Various factors change the exact date and time every year, but aphelion (when we’re farthest from the Sun) happens in July, and perihelion (when we’re closest) in January.
At perihelion, our planet is about 91 million miles from the Sun. It moves outward to about 95 million miles from the Sun at aphelion. So, the Earth is about three percent farther from the Sun at aphelion than it is at perihelion. Naturally, some people have the mistaken impression that our seasons are caused by the changes in Earth's distance from the Sun, but this is not the case.
The temperatures and the seasons are not affected by the proximity of the Earth to the Sun or even the rotation of the planet on its axis. Rather, it is the tilt of the Earth that determines the climate. When it is at perihelion in January, the Earth is tilted away from the Sun in the Northern Hemisphere, and the sunlight is not "getting a direct hit" on the Earth's atmosphere. However, when it is at aphelion in July, the Earth is tilted toward the Sun.
So, as we prepare for much colder air this coming week, take comfort in the fact that the Earth is closer to the Sun than it is in the middle of Summer. I'm sure that's of little consolation, though. Winter is just two weeks old as of today. We still have a long way to go until Spring.