The Moon
Also called: Moon, lunar.
Earth's only natural satellite, 3,474 km across and about 384,000 km away — the easiest telescope target of all.
The Moon goes round the Earth once a month, showing us the same face. Its phase changes as we see more or less of its sunlit side; the best detail is along the terminator, where shadows are long.
Its light is the biggest enemy of deep-sky observing: from about first quarter to last quarter, moonlight brightens the sky and hides faint galaxies and nebulae. Planets, double stars and the Moon itself don't mind.
At the eyepiece
Never look at the full Moon at high power without a moon filter if it dazzles you — and enjoy the crescent and quarter phases most.
In AstroPilot
Tonight shows the Moon's phase, rise and set, and how much it brightens the sky; every rating accounts for moonlight.