[Advaita-l] shivaraatri dates this year

[Raghav Kumar Dwivedula]

Thank you Anandji about the reason for tithis bring of different durations
being the eccentricity of the moon's orbit. I had assumed it's due to
inclination with ecliptic which gives it lower relative velocity along the
ecliptic when it crosses it, as being the cause. Truth is it's a minor
contributory factor since it's only a 5 degree inclination. What you
mentioned is the main cause.

 I did a rough calculation and it's clear that the change in lunar velocity
due to equal areas being covered  in equal intervals of time is the primary
factor for the change in moon's synodial velocity which in turn determines
tithi duration.

 Thank you for the clarification.

Om
Raghav

On 04-Feb-2018 7:01 PM, "Anand Hudli via Advaita-l" <
advaita-l at lists.advaita-vedanta.org> wrote:

> Shri Raghav Kumarji,
> >>>>
> One small follow up question - why does the tithi ending time differ in the
> two methods. My first level understanding about tithi determination is that
> it's the time taken by the moon to move 12 degrees away from the sun. And
> so 30 tithis will be there in one month. The tithi durations will differ
> because the lunar orbit is not in the ecliptic plane but inclined at about
> 5 degrees to the ecliptic.
> >>>>
>
> There are different methods of computing the moon's and sun's position
> (specifically celestial longitude). The sUryasiddhAnta is an ancient method
> but modern methods promise a higher degree of accuracy. This has led many
> panchanga makers to opt for modern methods
> or more recent methods such the dRg-gaNita method. The difference in the
> moon's position, especially, depending on the method used, could run into
> degrees of the arc, not just seconds or minutes. This could lead to the
> difference in tithi ending times of several hours that we see
> in different panchangas. This in turn could lead to the same observance,
> eg. shivarAtri, being declared on different dates by different panchangas.
>
> >>>>
> So some tithis will be long like about 29 hours
> and some short like 19 hours or so in each lunar month. In the geocentric
> astrological chart this can be visualized as the moon moving sometimes
> faster (shorter tithi) and sometimes slower (longer tithi)That is also why
> lunar eclipses will not occur every month. Also right now a lunar eclipse
> has just occurred so the moon is on the ecliptic plane . Which means the
> tithi duration will be relatively shortest now and longest 15 days later .
> >>>>
>
> The variation in the moon's speed directly follows from Kepler's law for
> bodies in elliptical orbits, which states that the line joining an orbiting
> body (moon) with its center (at one of the foci) sweeps out equal areas in
> equal intervals of time. The speed at the perigee when
> the moon is closest to earth is higher than the speed at the apogee when
> the moon is farthest from earth. A nice explanation is found here:
> http://www.phy6.org/stargaze/Skepl2A.htm
> The speed of the moon may not have anything to do with eclipses per se. If
> the moon happens to be near the perigee at the time of eclipse, then the
> speed would also be higher. Else not. Yes, you are right in saying a faster
> (slower) moving moon means shorter (longer) tithis.
>
> Anand
>
>
>
>
> On Thu, Feb 1, 2018 at 10:26 PM, Anand Hudli <anandhudli at hotmail.com>
> wrote:
>
> > Correction:
> >
> > "The nishItha kAla is obtained by dividing the duration of the night
> > (i.e. from sunset to sunset the next day) into 15 parts and taking the
> > eighth such part."
> > should read- "The nishItha kAla is obtained by dividing the duration of
> > the night (i.e. from sunset to *sunrise* the next day) into 15 parts and
> > taking the eighth such part."
> >
> > Anand
> >
> >
> > On Thu, Feb 1, 2018 at 10:18 PM, Anand Hudli <anandhudli at hotmail.com>
> > wrote:
> >
> >> >The kanchi mutt is following the कालमाधवीयं and sriCngeri mutt is
> >> following धर्मसिन्धु...
> >>
> >> >Former is celebrating on 14th and the later on 13th !!
> >>
> >> Dear Shri Sriramji,
> >>
> >> I looked at both the (Kannada) Sringeri and (Telugu version) Kanchi
> Matha
> >> Panchangas. First of all, the tithi ending times are telling us that
> >> Sringeri uses (the ancient) Surya Siddhanta method of determining tithi
> >> ending times, while Kanchi uses dRg-gaNita. The starting and ending time
> >> for Chaturdashi tithi are 1) 10:15 PM on Feb 13 and 12:11 AM on Feb 15
> as
> >> per Surya siddhAnta and 2) 10:34 PM on Feb 13 and 12:46 AM on Feb 15 as
> per
> >> dRg-gaNita. Now, the rule for mahAshivarAtri states that Chaturdashi
> should
> >> prevail during the nishItha kAla of the day when we observe it. The
> >> nishItha kAla is obtained by dividing the duration of the night (i.e.
> from
> >> sunset to sunset the next day) into 15 parts and taking the eighth such
> >> part. The sunset times at Sringeri and Kanchi differ too, since Sringeri
> >> sunset is at 6:33 PM and Kanchi sunset is at 6:16 PM. Taking the
> duration
> >> of the night as approximately 12 hours (this is sufficient for this
> >> instance, although the actual duration of night is slightly more than 12
> >> hours), each 1/15 part of the night is 48 minutes, which is, by the way,
> >> the duration of a muhUrta. The eighth such part (nishItha kAla) starts 5
> >> hours 36 minutes after sunset. In Sringeri, this would be 12:09 AM on
> Feb
> >> 14 and in Kanchi it would be 11:52 PM on Feb 13. On the next day, the
> start
> >> of nishItha kAla is about the same in the two places. The ending time
> for
> >> the nishItha kAla would be 12:57 AM on Feb 14 in Sringeri and 12:40 AM
> on
> >> Feb 14 in Kanchi. The interesting point to note is that the vyApti of
> >> Chaturdashi is kArtsnyena (complete, as dharmasindhu puts it) in
> Sringeri
> >> on Feb 13-14 night and ekadeshena (partially) on Feb 14-15 night as per
> >> Sringeri's method, ie. sUrya siddhAnta. When this happens, the rule for
> >> shivarAtri states that the first night, i.e. Feb 13-14, should be
> selected
> >> for observing shivarAtri (paredyuH nishItha-ekadesha-vyAptau pUrvedyuH
> >> saMpUrNatadvyAptau pUrvaiva). Hence Feb 13-14 is the shivarAtri date for
> >> Sringeri. The same would have been the case for Kanchi, had it not been
> for
> >> the dRg-gaNita method which makes the ending time of Chaturdashi 12:46
> AM,
> >> beyond the ending of nishItha kAla at 12:40 AM. As an interesting twist,
> >> there is not ekadesha-vyApti but saMpUrNa-vyApti even on the second
> night,
> >> i.e. Feb 14-15 *and* saMpUrNa-vyApti on the first night , i.e. Feb
> 13-14 in
> >> Kanchi! When this happens, another rule applies which says the majority
> of
> >> the dharmashAstra-kAras recommend the second night, i.e. Feb 14-15 in
> this
> >> case, while Hemadri and those who follow Hemadri recommend the first
> night.
> >> It appears that Kanchi has taken the majority opinion, which includes
> >> weighty granthas such as nirNyaya-sindhu, kAlamAdhava, and puruShArtha
> >> chintamaNi. Hence, Feb 14-15 is the shivarAtri date for Kanchi.
> >>
> >> Anand
> >>
> >>
> >
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