A ring around the Moon (a “lunar halo”) happens when moonlight passes through high, thin clouds made of tiny ice crystals in Earth’s upper atmosphere, which bend and focus the light into a circle.

Quick Scoop: What You’re Seeing

  • The ring is not around the Moon itself but in our sky, in the layer of air above you.
  • It usually appears as a pale, whitish circle about 22 degrees from the Moon, often with a faint rainbow-like tint.
  • These rings are most often seen when there are thin cirrus clouds very high up, 5–10 km or more above Earth.

How the Ring Forms (Simple Version)

  • High cirrus clouds contain hexagon-shaped ice crystals that act like tiny prisms or lenses.
  • As moonlight passes through these crystals, it is refracted (bent) by a specific angle, concentrating light into a ring around the Moon.
  • Because the crystals tend to have similar shapes, the angle is almost always the same, giving the common 22° halo (your outstretched hand at arm’s length roughly matches that size).

Extra Details & Cool Bits

  • Sometimes, under special conditions, a fainter second ring at about 44° can appear farther out from the Moon.
  • The halo can show subtle colors because different wavelengths of light refract by slightly different amounts, a bit like a very washed-out rainbow.
  • Everyone sees their “own” halo, because the ice crystals lining up for your eyes are different from those lining up for someone standing a few meters away.

Does It Mean Bad Weather?

  • Old weather lore says, “Ring around the Moon, rain or snow soon,” and there is a grain of truth to it.
  • Cirrus clouds that create the halo often arrive a day or two ahead of a warm front and low-pressure system, which can bring rain or storms.
  • It is not a guarantee of bad weather, but it can be a hint that the atmosphere is changing.

Quick TL;DR

  • A ring around the Moon is a lunar halo caused by moonlight bending through high, icy cirrus clouds.
  • It is an atmospheric optical effect, not a physical ring around the Moon itself, and sometimes it can hint that wetter weather is on the way.

Information gathered from public forums or data available on the internet and portrayed here.