What is the approximate tilt of Earth's axis?

• A. 23.5 degrees
• B. 45 degrees
• C. 90 degrees
• D. 10 degrees

Answer: (A)

The tilt of Earth's axis relative to its orbit around the Sun is about 23.5 degrees. This tilt, called axial obliquity, means that as Earth travels around the Sun, different hemispheres lean toward or away from the Sun. That changes how high the Sun climbs in the sky and how long each day lasts, which is why we have seasons. When the Northern Hemisphere tilts toward the Sun, days are longer and sunlight is more direct, producing summer; six months later it tilts away, giving shorter days and winter. The current value is around 23.44 to 23.5 degrees. A tilt of 45 or 90 degrees would produce far more extreme or different seasons, and 10 degrees would yield much milder seasonal changes, so about 23.5 degrees best matches what we experience.