Moonless describes a night when the moon isn't visible in the sky, making everything darker than usual. On a moonless night, you might notice how much harder it is to see the path ahead when you're outside, or how many more stars become visible without the moon's bright glow washing them out.

The moon goes through phases, and during what's called a new moon, it passes between Earth and the Sun, so the side facing us receives no sunlight. Those nights are truly moonless: no crescent, no glow, nothing. Other nights might be moonless simply because clouds cover the moon, or because it hasn't risen yet.

Moonless nights matter in different ways. Astronomers love them because they can see distant galaxies and faint stars without moonlight interfering with their telescopes. Sailors historically found moonless nights challenging for navigation. Animals that hunt at night, like owls, may find it harder to spot prey. And if you've ever gone camping on a moonless night, you know how important a good flashlight becomes: the darkness can feel complete, especially far from city lights.