Tolkien is one of the northernmost craters on Mercury, located in the Borealis quadrangle (north pole region) at 88.82 N, 211.08 W., accessed 19 February 2019 It is 50 km in diameter. It was named after the South African born British writer J. R. R. Tolkien. The name was approved by IAU's Working Group for Planetary System Nomenclature on August 6, 2012. Since Tolkien is very close to the north pole, and Mercury has almost no axial tilt, Tolkien receives very little sunlight. S band radar data from the Arecibo Observatory collected between 1999 and 2005 indicates a radar-bright area covers the entire floor of Tolkien, which is probably indicative of a water ice deposit.Chabot, N. L., D. J. Lawrence, G. A. Neumann, W. C. Feldman, and D. A. Paige, 2018. Mercury's Polar Deposits. In Mercury: The View After MESSENGER edited by Sean C. Solomon, Larry R. Nittler, and Brian J. Anderson. Cambridge Planetary Science. Chapter 13, Figure 13.2.PIA19411: Water Ice on Mercury, NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of WashingtonJohn K. Harmon, Martin A. Slade, Melissa S. Rice, 2011. Radar imagery of Mercury’s putative polar ice: 1999–2005 Arecibo results. Icarus, 211, p37-50. doi.org/10.1016/j.icarus.2010.08.007
See also List of craters on Mercury
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