Perihelion, Aphelion and the Solstices
Changing Elliptical Orbit
The Earth orbits the Sun in an elliptical path, which means that there is one point on the path closest to the Sun and one point that is farthest away from the Sun.
Orbit Changes Shape
This path's shape varies due to the gravitational influences of other planetary objects, particularly the Moon. Approximately every 100,000 years, the Earth's orbital path changes from being nearly circular to elliptical. The difference of the Earth’s orbital shape from a perfect circle is known as its eccentricity. An eccentricity value of 0 is a circular orbit, while values between 0 and 1 describe an elliptical orbit.
Aphelion in Washington DC, District of Columbia, USA is on
Monday, July 5, 2021 at 6:27 pm EDT (Change city)
Distance from the Sun's center to Earth's center will be 152,100,527 km (94,510,886 mi)
|2021||January 2, 2021 8:50 am||91,399,454 mi||July 5, 2021 6:27 pm||94,510,886 mi|
|2022||January 4, 2022 1:52 am||91,406,842 mi||July 4, 2022 3:10 am||94,509,598 mi|
|2023||January 4, 2023 11:17 am||91,403,034 mi||July 6, 2023 4:06 pm||94,506,364 mi|
|2024||January 2, 2024 7:38 pm||91,404,095 mi||July 5, 2024 1:06 am||94,510,539 mi|
|2025||January 4, 2025 8:28 am||91,405,993 mi||July 3, 2025 3:54 pm||94,502,939 mi|
|* All aphelion/perihelion times are in local Washington DC time.|
Earth's Perihelion and Aphelion
The Earth is closest to the Sun, or at the perihelion, about two weeks after the December solstice, when it is winter in the Northern Hemisphere. Conversely, the Earth is farthest away from the Sun, at the aphelion point, two weeks after the June solstice, when the Northern Hemisphere is enjoying warm summer months.
Is the Timing a Coincidence?
Due to variations in the eccentricity of the Earth's orbit, the dates when the Earth reaches its perihelion or aphelion are not fixed. In 1246, the December Solstice was on the same day as the Earth reached its perihelion. Since then, the perihelion and aphelion dates have drifted by a day every 58 years. In the short-term, the dates can vary up to two days from one year to another.
Mathematicians and astronomers estimate that in 6430, over 4000 years from now, the perihelion will coincide with the March equinox.
Perigee and Apogee
The Moon's path around the Earth is also elliptical. The point in the Moon's orbit that is closest to the Earth is called the perigee and the point farthest from the Earth is known as the apogee. The terms are also sometimes used interchangeably with the Earth's perihelion and aphelion.
Did You Know...
...that the words perihelion and aphelion come from ancient Greek, where peri means close, apo means far, and helios means the Sun? They are used in astronomy to refer to the closest and farthest points of the orbits of any object revolving around the Sun. Together, they are called apsides - the points of least or greatest distance of a celestial object in orbit around another astronomical body.