chasmas

Noun

chasma (plural chasmas or chasmata)

1. A long, narrow, steep-sided depression on a planet (often other than Earth), a moon, or another body in the Solar System.
   • 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...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...
2. (obsolete, rare) An aurora.
   • Thus Cornelius Gemma, Professor of Medicine in Louvain, mentions them [the aurora borealis] under the name of chasma, as appearing in Brabant on the 13th February and 28th September, 1575.1814 December, Thomas Thomson, “On the Aurora Borealis”, in Annals of Philosophy; or, Magazine of Chemistry, Mineralogy, Mechanics, Natural History, Agriculure, and the Arts, volume IV, number XXIV...