Eclipse
Also called: lunar eclipse, solar eclipse, totality.
When one body moves into another's shadow: the Moon into Earth's (lunar eclipse) or the Moon's shadow onto Earth (solar).
A lunar eclipse happens at full Moon, when it passes through Earth's shadow and turns coppery red; it's visible from the whole night side of the Earth. A solar eclipse happens at new Moon, when the Moon blocks the Sun — total only along a narrow path.
Jupiter's moons are eclipsed too, when they pass into Jupiter's shadow and fade out in a few minutes.
At the eyepiece
A lunar eclipse is safe to watch with any optics. A solar eclipse needs certified eclipse glasses or a solar filter except during totality.
In AstroPilot
Tonight's “Coming up” lists eclipses visible from your location, with the contact times.