How does the Moon’s distance from Earth affect whether a solar eclipse is total or annular?

The Moon’s distance from Earth is a primary factor in determining whether a solar eclipse is total or annular because it dictates the Moon's apparent size in the sky relative to the Sun.12

Because the Moon travels in an elliptical orbit, its distance from Earth varies throughout the month. Similarly, Earth’s orbit around the Sun is elliptical, causing the Sun’s apparent angular diameter to change slightly.32

• Total Solar Eclipse: This occurs when the Moon is close enough to Earth that its apparent disk is large enough to completely cover the Sun’s disk as seen from an observer within the umbra.32
• Annular Solar Eclipse: This occurs when the Moon is at or near its greatest distance from Earth while the Sun is relatively near to Earth. In this position, the Moon’s apparent disk appears smaller than the Sun’s. Consequently, the Moon cannot cover the Sun completely, leaving a visible rim or ring of light around the Moon’s silhouette.32

These variations in distance mean that the Moon’s ability to obscure the Sun depends on the specific geometry of these celestial bodies at the time of the eclipse.3