Mommur Chasma


Voyager 2 image of Oberon showing Mommur Chasma near the limb at upper right.

Mommur Chasma is the largest 'canyon' on the known part of the surface of Uranus' moon Oberon.[1] This feature probably formed during crustal extension at the early stages of moon's evolution, when the interior of Oberon expanded and its ice crust cracked as a result.[2] The canyon is an example of graben (rift valley) or scarp produced by normal fault(s). The chasma was first imaged by Voyager 2 spacecraft in January 1986.[3]

The Gazetteer of Planetary Nomenclature states that Mommur Chasma is named after the forest home of the fairy king Oberon in A Midsummer Night's Dream.[1] In fact, Oberon's home is not named in Shakespeare's play; it appears instead in the French epic Huon of Bordeaux.


  1. ^ a b USGS/IAU (October 1, 2006). "Mommur Chasma on Oberon". Gazetteer of Planetary Nomenclature. USGS Astrogeology. Retrieved 2012-03-28.
  2. ^ Croft, S.K. (March 1989). New Geologic Maps of the Uranian Satellites Titania, Oberon, Umbriel and Miranda. Proceeding of Lunar and Planetary Sciences. 20. Lunar and Planetary Sciences Institute, Houston. p. 205C. Bibcode:1989LPI....20..205C.
  3. ^ Smith, B. A.; Soderblom, L. A.; Beebe, A.; Bliss, D.; Boyce, J. M.; Brahic, A.; Briggs, G. A.; Brown, R. H.; Collins, S. A. (4 July 1986). "Voyager 2 in the Uranian System: Imaging Science Results". Science. 233 (4759): 43–64. Bibcode:1986Sci...233...43S. doi:10.1126/science.233.4759.43. PMID 17812889.