Why do the Sun and the Moon appear about the same size in Earth’s sky?

The Sun and the Moon appear to be nearly the same angular size in Earth’s sky—approximately 0.5°—due to a remarkable coincidence regarding their physical sizes and their respective distances from Earth.1

While the Sun is vastly larger than the Moon, it is also significantly farther away. Because both bodies follow elliptical orbits, their distances from Earth fluctuate, which causes their apparent sizes to change slightly throughout the year and month.1

• Total Eclipses: When the Moon is closer to Earth (near perigee) during a solar eclipse, its apparent disk is large enough to completely cover the Sun’s disk.12
• Annular Eclipses: When the Moon is farther from Earth (near apogee), its apparent disk is smaller than the Sun’s, resulting in an annular eclipse where a ring of sunlight remains visible around the Moon.12

This relationship is a matter of geometric perspective rather than an intrinsic equality in size.1