Fact #149
Observing
During a total lunar eclipse near sunrise or sunset it is sometimes possible to see the eclipsed Moon and the Sun in the sky at the same moment, which geometrically should be impossible.
An eclipse means Earth is directly between them, so both cannot be above the horizon at once. Refraction cheats: the atmosphere bends the light of a body just below the horizon into view, lifting each image by about half a degree. Two half-degrees is enough. It is called a selenelion, and it needs a flat horizon and luck.
Source: Meeus, Mathematical Astronomy Morsels · checked Sep 2026