Aphelion - Perihelion
The word "perihelion" stems from the Ancient Greek words "peri", meaning "near", and "helios", meaning "the Sun". "Aphelion" derives from the preposition "apo", meaning "away, off, apart". (The similar words "perigee" and "apogee" refer to the nearest and furthest points in some object's orbit around the Earth.)
According to Kepler's first law of planetary motion, all planets, comets, and asteroids in the Solar System have approximately elliptical orbits around the Sun. (Any single revolution of a body around its parent object is only approximately elliptical, because precession of the perihelion prevents the orbit from being a simple closed curve such as an ellipse.) Hence, an orbiting body has a closest and a farthest point from its parent object, that is, a perihelion and an aphelion, known collectively as apsides. Orbital eccentricity measures the flatness (departure from a perfect circle) of the orbit.
When Earth is closest to the Sun, it is winter in the northern hemisphere and summer in the southern hemisphere. Hence, Earth's distance from the Sun does not significantly affect what season occurs. Instead, Earth's seasons come and go because Earth does not rotate with its axis exactly upright with respect to the plane of its orbit around the Sun. Earth's axial tiltis 23.4 degrees. This puts the Sun further south in December and January, so the north has winter and the south has summer. Thus winter falls on that part of the globe where sunlight strikes least directly, and summer falls where sunlight strikes most directly, regardless of the Earth's distance from the Sun.