Tolkien (crater)

{{short description|Crater on Mercury}}

{{Infobox crater data

| title = Tolkien

| image = Tolkien crater EW0262000395G.jpg

| caption = MESSENGER image with Tolkien at center. The north pole is on the rim of Tryggvadóttir, the crater at left foreground.

| globe = Mercury

| coordinates = {{coord|88.82|N|211.08|W|globe:mercury_type:landmark|display=inline,title}}

| diameter = 50 km

| eponym = J. R. R. Tolkien

}}

Image:PIA19247-Mercury-NPolarRegion-Messenger20150316.jpg

File:Radar-bright Deposits near Mercury's North Pole messenger orbit image20120322.jpg

Tolkien is one of the northernmost craters on Mercury, located in the Borealis quadrangle (north pole region) at 88.82 N, 211.08 W.{{gpn|15025}}, 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.{{cite web|url=http://www.nasa.gov/mission_pages/messenger/media/PressConf20121129.html|title=Permanently Shaded Polar Craters|publisher=NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory|date=15 November 2012}} 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.{{cite web|url=http://photojournal.jpl.nasa.gov/catalog/PIA19247|title=Hot and Cold|author=NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington|date=16 March 2015}}[https://photojournal.jpl.nasa.gov/catalog/PIA19411 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. [https://doi.org/10.1016/j.icarus.2010.08.007 doi.org/10.1016/j.icarus.2010.08.007]

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