Happy Perihelion 2023: Close to the Sun

It is that time of year again when Earth makes a close swing by the Sun!

On January 4, 2023, at 16:17 UTC (11:17 a.m. EST or 8:17 a.m. PST), Earth’s orbit will be at our closest point to the Sun for the year.

A cartoon of the Sun swinging Earth. Earth orbiting around the Sun. credit: Cartoon via Sara Zimmerman at UnEarthed Comics. (shared by Earthsky.org)

This point of closest approach to the Sun is called perihelion. The point when Earth is farthest from the Sun is called aphelion.

Aphelion versus Perihelion. (Orbits exaggerated). Image credit: NOAA/NASA.

• These terms are specific to a body orbiting the Sun.
• For satellites of Earth (including the Moon), the points of the farthest and closest approach are called apogee and perigee, respectively.
• The generic terms for the farthest and closest approach of a body in an elliptic orbit about a larger body are apoapsis and periapsis, respectively.

The diagram below shows the times and positions of the Earth during the solstices, equinoxes, perihelion, and aphelion as it orbits the sun over a year.

Credit: http://bit.ly/1pQn7wy

This diagram shows the relation between the line of solstice and the line of apsides of Earth’s elliptical orbit. The orbital ellipse (with eccentricity exaggerated for effect) goes through each of the six Earth images, which are sequentially the points of:

• Perihelion (periapsis—nearest point to the sun) on anywhere from 2 January to 5 January
• March equinox on 20 or 21 March
• June solstice on 20 or 21 June
• Aphelion (apoapsis—the farthest point from the sun) on anywhere from 4 July to 7 July
• September equinox on 22 or 23 September,
• December solstice on 21 or 22 December.

A common misconception is that seasons are caused by our distance from the Sun. Learn more »

• At aphelion Earth is 1.0167 Astronomical Units (AUs) or 152,093,250 kilometers (94,506,364 miles) from the sun
• At perihelion, it is 0.9833 AU or 147,098,924 kilometers (91,403,034 miles) from the sun.

However, the times of greatest solar radiation on a hemisphere happen not because of the distance between the Earth and sun but the tilt of Earth’s rotation axis. These times are during the December and June solstices.

Here are Earth’s perihelions and aphelions for 2023 through 2026.

Spacecraft Also Have Perihelion & Aphelions

Upcoming closest approaches to the Sun of note are:

• The next perihelion for NASA’s Parker Solar Probe is March 17, 2023.
• The next perihelion for ESA’s Solar Orbiter is also in April 10, 2023.