Perihelion Day 2024

Earth's closest approach to the sun

Today is Perihelion Day, January 3rd, when Earth is closest to the sun in its 2024 orbit—approximately 3 million miles nearer than its farthest point, known as aphelion. Perihelion usually occurs about two weeks after the winter solstice, the Northern Hemisphere's shortest day.

It underscores Earth's elliptical orbit, not a perfect circle, with today's distance from the sun at about 91.4 million miles. Research from the University of California, Berkeley, suggests sunlight is around 7% more intense during perihelion compared to aphelion.

According to Space.com, 'perihelion' comes from Greek, where 'peri' means around and 'helios' refers to the sun. In contrast, 'aphelion' indicates the farthest point in an orbit from the sun. Orbits in the universe frequently adopt elliptical shapes rather than perfect circles.

Orbits vary in eccentricity, ranging from slightly elliptical, resembling a slightly squashed circle with low eccentricity, to more elongated and highly eccentric. These diverse orbital shapes contribute to the dynamic nature of celestial paths in the cosmos.