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The southern end of the Ithaca Chasma, a chasma on Saturn’s moon Tethys which is one of the longer valleys in the Solar System, photographed by the Cassini–Huygens space probe during its closest approach to the moon on 24 September 2005. The mission was brought to an end on 15 September 2017 by having the probe make a controlled descent into Saturn’s atmosphere.

From Latin chasma, from Ancient Greek χάσμα (khásma, abyss, cleft), from Ancient Greek χᾰ́σκω (kháskō, to gape, yawn) (possibly from Proto-Indo-European *ǵʰan-, *gʰan- (to gape, yawn) + -σκω (-skō, inchoative suffix forming a present-tense word), from Proto-Indo-European *-sḱéti (suffix forming a durative or iterative imperfective verb); or from Proto-Indo-European *ǵʰeh₁y- (to gape, yawn)) + Ancient Greek -μᾰ (-ma, suffix forming a noun denoting the result of an action) (from Proto-Indo-European *-mn̥ (suffix forming an action or result noun)).

The obsolete “aurora” sense is from the fact that aurorae were thought to be rifts in the sky from which light shone through: see the 1822 quotation.



chasma (plural chasmas or chasmata)

  1. (astronomy, geology) A long, narrow, steep-sided depression on a planet (often other than Earth), a moon, or another body in the Solar System.
    • 1991 June 1, Steven K. Croft, “Tethys Geology and Tectonics Revisited”, in Reports of Planetary Geology and Geophysics Program (NASA Technical Memorandum; accession number 92N10765, document ID 19920001547)‎[1], Washington, D.C.: Scientific and Technical Information Branch, National Aeronautics and Space Administration, OCLC 25563920, archived from the original on 26 September 2016, page 98:
      The most prominent tectonic feature on Tethys is the globe-girdling Ithaca Chasma, which is 60 to 100 km wide, 3–4 km deep, and can be traced through at least 270° of a rough great circle (Smith et al, 1982; Moore & Ahern, 1983). [] Odysseys Tangent Chasma. A prominent chasma 60–80 km wide and at least 800 km long (90° arc), visible in 80.27, is tangent to the rim of Odysseus, trending about 10° east of north. The chasma intersects a ridge-bounded trough radial to Odysseus [] and is then lost in the zone around the North Pole that is shadowed in all of the extant images.
    • 2003, David Leverington, “The Space Age – Terrestrial Planets”, in Babylon to Voyager and Beyond: A History of Planetary Astronomy, Cambridge: Cambridge University Press, →ISBN, page 398:
      Venus shows clear signs of past tectonic activity in the highland regions. The deformational (tectonic) features showing[sic, meaning show] the results of both compressional and extensional forces. Rifting of the crust has occurred to produce relatively shallow chasmas and abundant faulting in the Aphrodite Terra and Beta Regio highlands []
    • 2007, Mary G. Chapman; John L. Smellie, “Mars Interior Layered Deposits and Terrestrial Sub-ice Volcanoes Compared: Observations and Interpretations of Similar Geomorphic Characteristics”, in Mary [G.] Chapman, editor, The Geology of Mars: Evidence from Earth-based Analogs (Cambridge Planetary Science), Cambridge; New York, N.Y.: Cambridge University Press, →ISBN, page 203:
      Assuming a subglacial or subaqueous setting for the ILDs [interior layered deposits], a simple tectonic control (and associated rupture of a confined aquifer) alone seems an unlikely trigger for ILD volcanism, or we should also observe ILDs in the linear chasmata, for which a tectonic setting is most likely and in which ILDs are absent. We suggest that the method of formation of the elliptical chasmata and the ILDs may be genetically related.
    • 2014, Donald L[awson] Turcotte; Gerald Schubert, Geodynamics, 3rd edition, Cambridge: Cambridge University Press, →ISBN, page 83:
      The near circular trough of the Artemis chasma [on Venus] has a diameter of 2100 km. The concentric features outside the chasma are attributed to normal faulting associated with lithospheric flexure similar to that occurring seaward of subduction zones on the Earth.
  2. (astronomy, obsolete, rare) An aurora.
  3. Obsolete form of chasm.

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Borrowed from Ancient Greek χάσμα (khásma).


chasma n (genitive chasmatis); third declension

  1. A chasm, abyss
  2. A kind of meteor


Third-declension noun (neuter, imparisyllabic non-i-stem).

Case Singular Plural
Nominative chasma chasmata
Genitive chasmatis chasmatum
Dative chasmatī chasmatibus
Accusative chasma chasmata
Ablative chasmate chasmatibus
Vocative chasma chasmata


  • English: chasm, chasma


  • chasma in Charlton T. Lewis and Charles Short, A Latin Dictionary, Oxford: Clarendon Press, 1879
  • chasma in Gaffiot, Félix, Dictionnaire illustré Latin-Français, Hachette, 1934, page 299