8th Grade Sun-Earth-Moon System (C20) Practice Test 2026 - Free Astronomy Practice Questions and Study Guide

The key idea is that day length is set by the tilt of Earth’s axis relative to the Sun, not by how close we are to the Sun. The shortest daylight in the Northern Hemisphere happens when the Sun sits lowest in the sky at noon, which is during the winter solstice. On that day, the Sun’s path is at its southernmost extent and the Sun stays above the horizon for the least time, giving the minimum number of daylight hours.

Perihelion and aphelion are about Earth’s distance from the Sun—closest and farthest points in its orbit—so they affect how much solar energy we receive but not the length of the day. An eclipse is just an alignment event and doesn’t determine day length.

So the term that describes the time of year with the shortest days is the solstice, specifically the winter solstice.