Aphelion refers to the point in the orbit of a planet or any celestial object where it is farthest from the Sun. It is the opposite of perihelion, which is the point where the object is closest to the Sun. Aphelion and perihelion are terms used to describe the positions of objects in elliptical orbits, such as planets in our solar system.

The term "aphelion" is derived from the Greek words "apo," meaning "away," and "helios," meaning "Sun." It represents the farthest distance a planet or comet reaches from the Sun during its orbital path. The distance between the planet and the Sun is at its maximum at aphelion.

The location of aphelion is not fixed and varies depending on the planet's orbit. For example, in the case of Earth, aphelion occurs around July 4th each year. This is when Earth is farthest from the Sun in its elliptical orbit, at a distance of about 152 million kilometers (94.5 million miles). The date of aphelion can vary slightly due to gravitational interactions with other planets and the effects of Earth's axial precession.

Aphelion has significant implications for the seasons on a planet. Despite being farthest from the Sun during aphelion, the seasons are primarily determined by the tilt of a planet's axis. Earth's axial tilt of about 23.5 degrees causes the changing seasons, not the distance from the Sun. In fact, Earth is actually closest to the Sun during its Northern Hemisphere winter. Other planets with different axial tilts may experience different seasonal patterns due to their aphelion and perihelion distances.