Perihelion

Today, the Earth will reach its Perihelion at 8 P.M. Eastern Standard Time.  This is the point in the planet’s orbit where it comes closest to the Sun.

This annual event is due to the elliptical shape of the Earth’s orbit and the off-centered position of the Sun inside that path.  The exact date of the Perihelion differs from year to year, but it’s usually in early January…winter in the northern hemisphere.  We will be furthest from the Sun at the Aphelion in July.

The planet’s distance from the Sun does not cause the seasons, but it does influence their length.  As a function of gravity, the closer the planet is to the Sun, the faster it moves. Today, the Earth is about 146 million kilometers away from the Sun.  That is approximately 5 million kilometers closer than in early July.  This change in distance allows the planet to speed up by about one-kilometer/second.  As a result, winter in the northern hemisphere is about five days shorter than summer.  The opposite is true in the southern hemisphere.

The word, perihelion, is Greek for “near sun”.

The perihelion position of Earth's orbit.

Image Credit: Academy Artworks

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About Melissa Fleming

Melissa Fleming is an environmental communicator and visual artist working at the intersection of art and science. She is passionate about exploring, learning, and sharing information about the natural world. She has presented her interdisciplinary work in a variety of mediums at venues and conferences around the world.