January 3, 2026: Earth reaches perihelion as daylight slowly increases across the mid-northern latitudes. Learn how Earth’s orbit, astronomical units, and eccentricity affect seasons and sunlight.

by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:18 a.m. CST; Sunset, 4:32 p.m. CST. Times are calculated by the US Naval Observatory’s MICA computer program. Check local sources for sunrise and sunset times.
Daylight Lengthens
Daylight at the mid-northern latitudes is increasing. Today, at Chicago’s latitude, daylight spans 9 hours, 14 minutes. By month’s end, daylight increases by more than 45 minutes from today’s length, and sunset occurs at 5:05 p.m. Sunshine increases across the Northern Hemisphere, although the greatest daily gains occur at far northern latitudes. Sunrise remains at its latest time for another week before shifting earlier.
Earth at Perihelion

Earth is closest to the sun today (perihelion) at 11:16 a.m. Central Time. The separation is 0.9833 astronomical unit (A.U.). One astronomical unit equals Earth’s average distance from the sun, about 93 million miles. At aphelion next summer, Earth is 1.0166 A.U. from the sun.
The seasons result from Earth’s axial tilt, not from its distance from the sun. The solstice occurred about two weeks ago, maximizing direct sunlight across southern latitudes, while sunlight arrives at a lower angle and for shorter durations north of the equator.

Planets revolve around the sun in elliptical orbits rather than perfect circles. Earth’s orbit deviates from circular by 1.6%, producing a distance change of about 3 million miles between perihelion and aphelion. Mercury has the most eccentric planetary orbit in the solar system, differing from circular by 21%.
Measuring Distances
Astronomical units are used to describe distances within the solar system. This measurement simplifies comparisons among planets without relying on large numbers expressed in miles. For example, Jupiter’s average distance from the sun is 5.2 A.U., meaning it is 5.2 times farther from the sun than Earth.
Today marks perihelion, Earth’s closest point to the sun. Happy Perihelion Day!
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