... December 8, 1996 . Degas Ray Crater on Mercury . ... Explanation : Like the Earth's Moon, Mercury is scarred with craters, testifying to an intense bombardment during the early history of the Solar System. ... In the above mosaic the bright rays emanating from the 27 mile wide Degas crater almost appear to be painted on . The rays consist of light colored material blasted out during the crater's formation. Numerous smaller, younger craters are seen superposed on the Degas crater itself. ...

... The distance scales of the objects are matched both by comparing the first derivatives of the angular velocity determined separately from radial velocities and proper motions and by the statistical-parallax method. ... Good agreement between the inferred 0 and our calculations based on space velocities suggests that the Lindblad relation holds throughout the entire sample volume. ... Brandt and Blitz (1993) published the distances and radial velocities for a total of 206 H II-regions. ... Astron. ...