What is the length of a solar day?

A solar day is defined as the time it takes for the Earth to rotate once on its axis relative to the sun, which is approximately 24 hours. More precisely, a solar day is the interval between two successive appearances of the sun at the same position in the sky as observed from a fixed location. Due to the Earth's elliptical orbit and axial tilt, there are slight variations in this period over the course of a year.

In contrast, a sidereal day, which is based on the Earth's rotation relative to distant stars, is approximately 23 hours and 56 minutes. This reflects the time it takes for the Earth to complete a full 360-degree rotation relative to stars rather than the sun. The confusion usually arises from the difference between solar time and sidereal time, which is an important concept in astronomy but not what defines the length of a solar day.

The other options relate to different concepts or provide incorrect specifics regarding the length of a solar day. A solar year, for example, is approximately 365.2422 days, which pertains to the time it takes Earth to orbit the sun, not the rotation period that defines a solar day.