An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) In 3D → magnetic reconnection models of solar plasma, a field line crossing the → fan at the → magnetic null point. See also → fan (Lau & Finn. 1990, ApJ 350, 672; Parnell et al. 1996, Physics of Plasmas 3, 759).
2) A very narrow line of light extending back from the coma into the tail of some → comets.

M.E., from O.Fr. espine, from L. spina "backbone," originally "thorn, prickle," cf. L. spica "ear of corn," O.N. spikr "nail;" from PIE *spei- "sharp point."

Xâr "spine, thorn," related to xal-, xalidan "to prick, to pierce," xâridan "to scratch, itch;" Av. x^vara- "wound, sore."

A mineral, MgAl₂O₄, occurring in various colors, used as a gem, the most valuable being red. The famous "Black Prince's Ruby" which forms part of the Crown Jewels of England, is, in fact, a red spinel. Spinel has often been confounded with → ruby. The most famous source of spinel is the historic region of Badakhshan (today northeastern Afghanistan and southeastern Tajikistan). The Badakhshan mines were mentioned by Persian writers as early as the 10th century. According to a Persian tradition, these mines were first disclosed when the mountain was broken open by an earthquake.

From Fr. spinelle, from It. spinella of unknown origin.  

Lâl, la'l "spinel; red," originally "red" (cf. Tabari âl "red"); cf. Av. raoidita- "red, reddish;" Skt. rudhirá- "red, bloody;" L. ruber "red;" Gk. erythros "red;" akin to E. → red.