Visibility of Luna and Lunar Crescent

vi€w of $udying ihe behaliour of lhe Rip.nes iunction oler a yea! for any pl&c
calculding Ie, for cvcry day of the yd is not useful. This is bc@w of thc &ct lhat
y€ar ro y€e dd da, (o day vdiarions in lalitude oflhe Moo. dd hence nd, ats not
dep€ndent on the rime of ye.!. However, *ith posiblc lalues of4, one cd calculate
el.v val@ of l* for @h day ofa yd &d study ns veialioG scenally as sell d
$irh chdging lalilude of pl.cc. As possiblc values of,, vary from l0 degcca lo 12
degc.s an appopdate value for the day oi day after conjunctioh is obtained only on the
bdis of the ule disraice o. sminimd.r of the Moon. Still tor a compdie. values of
lS6. foi dill@lt ladrudes, se calculaled lor both $e cxrene valucs ,, = loo dd a, -
120 and the curves,t,r aeainsr the longitude oflhe Suo (fiom March 2l) aft ploned in
FiSuGs (3 3 2) lo (3.1.5) These cw€s snow inleFsting featres lbat cs b€ sunmdized
i) from fi8.1.1.2 il is cl€ar rhar forg = O0 i... for a placc on $eequabr&i! is
sinusoid.l wirh mdina.t March 21, Septcmber 2l dd hinima at Ju.e 21.
D4ember 21. Snalle! v.lues of iG nems shaller lalues ]?d4 or !€lariv€ly
rounger cEsent m.y b€ rn. L&g€r values of x i" dcans largq valus iia
orrelaliv.ly oldcr crcscenl may b. seen. Thw close to equalor older cEsceht
nay be visible near equi.oxes and Elatilely younger cresc€nl .ea! ehrlc€s.
If $c Moon is nc{ jls apog€c lhen il is noving faner and apFaB rhicker in
sky Blatively younger cescents b€cone ripe for visibilny. Funher rhe
paencc of two maxim and two binima ihdicates four stong innecdon
points. There arc rwo regions ot lpMd concaviry (douod solsdcet dd rs
of downwdd concaviiy {&ound cquinoxs)
As rhc larirude of rhe place in rc66 (one move ro rhe nonh ofequabt $e
muinum ol1." at $e venal equjnox loseu nDline ir eard lo k d a
youngcr cescenr bul the ndimum of lhc veml equinox ris.s e $al it
becones norc difiiculr to ec a yodge! crc$ed (69. 3.3.3). On thc o$er
hmd fte ninimM of lhe s|!md ehric€ mo6 rowuds sdng (v.mal
equinox) ad that of rhe wintd rchric. mov€s rowds autumn (aurunnal
eqlinox) md in ei$er c& d.crcae funner making ir esier ro *e a younger
96