Perihelion
Astronomy
Near the Sun. The perihelion is the point on a planet's elliptical orbit around the Sun at which it makes its closest approach to the Sun.
According to Johannes Kepler's second law a planet travels fastest when closest to the sun.
The most distant point is the Aphelion.
The Earth's Perihelion
From year to year, 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) | |
| 2015 | January 4 | 06:36 | July 6 | 19:40 |
| 2016 | January 2 | 22:49 | July 4 | 16:24 |
| 2017 | January 4 | 14:18 | July 3 | 20:11 |
| 2018 | January 3 | 05:35 | July 6 | 16:47 |
| 2019 | January 3 | 05:20 | July 4 | 22:11 |
| 2020 | January 5 | 07:48 | July 4 | 11:35 |
Some astrologers consider the Earth's perihelion, otherwise known as diamond, to be significant.
The Seasons
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 tilt of 23.4 degrees 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.
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