The saying "a ring around the sun or moon" is true in the sense that it is a real phenomenon, but it doesn't necessarily mean what people might think.

What it is:

* Halo: The rings around the sun or moon are called halos. They are optical phenomena caused by the refraction and reflection of sunlight or moonlight through ice crystals in high-altitude clouds (cirrostratus).

What it doesn't mean:

* Predicting the weather: While halos are often associated with upcoming rain or storms, they don't reliably predict the weather. The presence of high-altitude clouds, which are necessary for halos, can sometimes precede rain, but they don't always.

* A "ring of fire": The saying often gets confused with a solar eclipse, which is a different phenomenon. A solar eclipse occurs when the moon passes directly between the sun and the Earth, blocking the sun's light.

In summary:

* Halos are real and caused by light interacting with ice crystals in clouds.

* They are not always associated with rain or storms.

* They are not the same as a solar eclipse.

So, while the saying "a ring around the sun or moon" might be true, it's important to understand the science behind it and not rely on it for weather predictions.