From time to time I ask people when they think Earth is closest to the Sun. They almost always say in the summer. That isn’t true. We are furthest from the Sun in the summer (in the northern hemisphere), and closest in January. I never really knew when we were the furthest, but thanks to Phil Plait, I know that day is today, and it’s called aphelion. Perihelion is when the Earth is closest to the Sun, and it’s in early January with aphelion happening six months later.
Many people don’t realize that our seasons are caused by the tilt of the earth, not by the distance from the sun. That is why the southern hemisphere has just the opposite seasons. It’s a pretty basic fact that if a person just stops and thinks about it for a bit, make perfect sense, yet people often miss it. And now you shouldn’t.