The 400-to-one coincidence is rounded, changeable and temporary. Its near-match hides the photosphere closely enough to expose the Sun's faint inner corona.
A total solar eclipse depends on an extraordinary coincidence: the Sun is about 400 times wider than the Moon but also roughly 400 times farther away, making them appear almost exactly the same size. Other planets experience eclipses, but none in our Solar System is known to offer Earth’s near-perfect match—the Moon hiding the Sun’s bright surface while exposing its corona.
The Long View