ray system

(redirected from Ray material)

ray system

[′rā ‚sis·təm]
(astronomy)
The bright streaks radiating outward from a lunar crater.
References in periodicals archive ?
At the center of each is a 3- to 5-km-wide impact crater gouged into bright ray material from Copernicus.
Second is the broad region surrounding the crater that's almost completely covered by bright ray material. And finally, there are the long crater rays themselves.
Additionally, a triangle-shaped zone of avoidance occurs uprange, where no ray material is deposited.
Looking at the larger scene reveals that Copernicus H was formed when an object impacted into bright ray material ejected by Copernicus.
Compositional rays fade for this reason and also because small impacts physically mix the ray material with the surrounding darker lunar surface.
This is actually highland rock debris that was excavated from below the layer responsible for the ray material. With excellent seeing and high magnification you can see that the halo covers the rays, demonstrating that the ray material was ejected first and then was buried by the halo material excavated from deeper underground.
But when the libration is good and it is near full Moon, the inner wall of the crater can be seen to be crossed by two or more bright stripes of ray material.
If this interpretation is correct, Dionysius must have excavated and scattered a localized dark volcanic ash deposit or lava flow as ray material. Other nearby, smaller craters may not have dug down deep enough to tap into this dark material.
Graham Ryder (Lunar and Planetary Institute) and his colleagues at the Johnson Space Center in Houston argue that this KREEP is shocked ray material excavated from the Apennine Bench by Autolycus.
Tenders are invited for E tender of x ray film and x ray materials