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.

View of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap.
View of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap.

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.

black and gray desk globe
Photo Caption – Earth Globe (Photo by lilartsy on)

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.

elliptical orbit
Image Caption – Elliptical orbit: This chart shows a hypothetical planet with an orbit 15% deviating from circular. The closest point to the sun (perihelion) and farthest point from the sun (aphelion) shown. – generated by AI

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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