Aphelion
General
The point on a planet's elliptical orbit that is at greatest distance from the sun.
The nearest point to the sun is the perihelion.
According to Johannes Kepler's second law a planet travels slowest when farthest to the sun.
The Earth's Aphelion
From one year to the next, the Earth's perihelion and aphelion are moving through the zodiac very slowly. You need a very long time scale to watch their progress through the seasons. They make one complete cycle in 22,000 to 26,000 years. There is a corresponding movement of the position of the stars as seen from Earth that is called the apsidal precession.
The exact dates and times of the earth's perihelions and aphelions for several past and future years are listed in the following table:
| Year | Perihelion | Aphelion | ||
|---|---|---|---|---|
| Date | Time (UT) | Date | Time (UT) | |
| 2023 | January 4 | 16:17 | July 6 | 20:07 |
| 2024 | January 3 | 00:39 | July 5 | 05:06 |
| 2025 | January 4 | 13:28 | July 3 | 19:55 |
| 2026 | January 3 | 17:16 | July 6 | 17:31 |
| 2027 | January 3 | 02:33 | July 5 | 05:06 |
| 2028 | January 5 | 12:28 | July 3 | 22:18 |
| 2029 | January 2 | 18:13 | July 6 | 05:12 |
By some astrologers the Earth's aphelion is also called the Black Sun which may have astrological significance.
The Seasons
Earth's distance from the Sun does not significantly affect what season occurs. Instead, Earth's seasons come and go because it does not rotate with its axis exactly upright with respect to the plane of its orbit around the Sun. Earth's axial tilt of 23.4 degrees puts the Sun further south in December and January, so the north has winter and the south has summer. 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.
See also
Weblinks
- Wikipedia: Perihelion and aphelion
- Wikipedia: Planetary perihelion and aphelion (Table that shows the distances of the planets and dwarf planets from the Sun at their perihelion and aphelion)
- Wikipedia: Elliptic orbit
- Wikipedia: Kepler's laws of planetary motion