Fażijiet lunari: Differenza bejn il-verżjonijiet
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Wieħed jistenna li darba fix-xhar meta l-Qamar jgħaddi bejn id-Dinja u x-Xemx, meta l-Qamar ikun mitluf, id-dell tiegħu jaqa' fuq id-dinja u jikkawża eklissi solari. Bl-istess mod matul kull Qamar kwinta wieħed jistenna li d-dell tad-Dinja jaqa' fuq il-Qamar u jikkawża eklissi lunari. Ma narawx eklissi tax-Xemx u tal-Qamar kull xhar għaliex il-pjan tal-orbita tal-Qamar madwar id-Dinja hu maqlub b'xi ħames gradi relattivament mal-pjan tal-orbita tad-Dinja madwar ix-Xemx (il-pjan tal eklittika). Għalhekk, meta jkun hemm Qamar mitluf jew mimli, il-Qamar ikun il-fuq jew l-isfel minn linja dritta li tgħaddi mid-Dinja u x-Xemx. Tassew li biex ikun hemm eklissi, il-Qamar irid ikun mitluf jew mimli, imma biex ikun hemm eklissi irid ikun qiegħed qrib ħafna fejn jiltaqgħu il-pjan tal-orbita tad-Dinja madwar ix-Xemx u l-pjan tal-orbita tal-Qamar madwar id-Dinja (jiġifieri, f'wieġed min-nodi). Dan jiġri xi darbtejn fis-sena, u allura hemm bejn erba' u seba' eklissi fis-sena. Il-biċċa l-kbira minn dawn huma insinjifikanti; eklissi maġġuri tax-Xemx u l-Qamar huma rari ħafna.
=== Il-kalkulu tal-fażijiet lunari ===
Kemm għandu żmien il-Qamar bejn wieħed u ieħor, u allura l-fażi bejn wieħed u ieħor, nistgħu nikkalkulawh għal kull data billi ngħoddu l-ġranet minn data magħrufa ta' qamar mitluf (pereżempju l-1 ta' Jannar 1900 jew il-11 ta' Awwissu 1999) u nirriduċu dan in-numru modulo 29.530588853 (it-tul tax-xhar sinodiku). <includeonly>The difference between two dates can be calculated by subtracting the [[Julian day|Julian Day Number]] of one from that of the other, or there are simpler formulae giving (for instance) the number of days since December 31, 1899. However, this calculation assumes a perfectly circular orbit and therefore may be incorrect by several hours (it also becomes less accurate the larger the difference between the required date and the reference date); it is accurate enough to use in a novelty clock application showing moon phase, but specialist usage taking account of lunar apogee and perigee requires a more elaborate calculation.
== Calcolo delle fasi lunari ==
È importante preporre che le fasi lunari, in ambito [[Astronomia|astronomico]], sono calcolate <ref>Mees Jean, ''Astronomical Algorithms'', Richmond, VA, Willmann Bell, 1991</ref> e sempre riferite in termini di geocentricità <ref>Zagar Francesco, ''Astronomia sferica e teorica'', Bologna, Zanichelli, 1948</ref> cioè per un ipotetico osservatore collocato al centro della [[Terra]].
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