A lunar eclipse occurs when Earth passes between the Sun and the Moon in such a way that the Moon moves into Earth’s shadow. When a partial lunar eclipse is going on, the curved shadow of our planet is apparent on the Moon’s face; the Moon looks kind of like it is in a crescent phase, but the terminator line (the line between light and dark) is not curved the same way. When a total lunar eclipse is happening, the entire Moon is in Earth’s shadow, and the Moon looks full, but glows only faintly red.