rille Astr.
(rɪl)
[a. G. rille: see rill n.1]
One of the long narrow trenches or valleys observed on the surface of the moon. (Cf. rill n.1 3.)
| 1868 Lockyer Elem. Astron. §226 The rilles, of which 425 are now known, are trenches with raised sides more or less steep. 1878 ― Stargazing 350 Hours may be spent in examining the craters, rilles, and valleys on the surface. 1957 New Scientist 7 Nov. 16 Criss-crossing the lunar surface there are alignments of mountains, valleys and trench-like formations called rilles. 1971 Daily Colonist (Victoria, B.C.) 25 July 2/3 A gorge called Hadley Rille cuts an 80-mile long 1,200-feet-deep gash across the..face of the moon. 1977 A. Hallam Planet Earth 15/3 These features, known as rilles, are shallow, often sinuous, valleys that cut across the maria. |