There's no such thing as a "ray" on the moon in the way you might be thinking. You're probably referring to the bright streaks of material that radiate outward from some lunar craters, most notably the famous Tycho crater.

These streaks are called rays, and they're not actually rays of light. They are ejecta – material blasted out of the crater when it was formed by an impact.

Here's what a ray on the moon looks like:

* Color: They appear brighter than the surrounding lunar surface, often having a whitish or grayish color.

* Shape: They're long, narrow streaks that radiate out from the crater in all directions.

* Width: The width of rays can vary, but they're typically much narrower than the crater itself.

* Length: Rays can extend for hundreds of kilometers from the crater.

The rays are made up of finely pulverized rock and dust, which reflects sunlight more efficiently than the darker lunar surface. This is why they appear bright.

Here's an important point: rays are not permanent features. They slowly fade over time due to micrometeoroid impacts and the constant bombardment of solar wind particles. The youngest craters, like Tycho, have the most prominent rays.

You can find more information on lunar rays by searching online for "lunar rays" or "ejecta rays". Many websites and resources have detailed information and images of these interesting features.