Sentence:  A computer program especially suited to the simulation of <WSD>Earth-grazing</WSD> meteors has been listed and described in the Astronomical Computing department of Sky & Telescope. The program allows for the curvature of the Earth; it is therefore possible to follow an <WSD>Earth-grazing</WSD> meteor as it descends, reaches perigee, and then ascends back into space. 
Meaning of the word marked with <WSD> tags:  Of a meteoroid: entering the Earth's atmosphere and leaving into space again.