New moon - when?

I was just trying to look up when I could expect to see the moon again,
and something struck me, which I hope you can clear up for me.

The "invisible" (I don't know exactly how a new moon is defined, as
you'll see) moon is almost coincident with the Sun, and so rises and
sets with it.

Believe it or not, that's only just occurred to me - amazing what
retirement can do.

So it's obscured by the sun's glare, and not illuminated.

As it moves away from the Sun, there will be an illuminated crescent,
but first it will be very tiny, and close to the Sun.

So the question is, at what (angular) distance from the Sun can I expect
the moon to have a visible crescent _and_ be far enough away in
degrees to be visible against the Sun, and distant in time to set (rise
for an old moon - I theeeenk), so that it could be expected to be
observed.

And is there an official definition that agrees with practical
observational factors (or doesn't)

Thanks for any enlightenment

mike

Hi Mike,

You can find a good article on it at:
http://skyandtelescope.com/observing...cle_1173_1.asp

Hope this helps.

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/
And the Lunar Picture of the Day http://www.lpod.org/
************************************

"mike ring" wrote in message
52.50...
I was just trying to look up when I could expect to see the moon again,
and something struck me, which I hope you can clear up for me.

The "invisible" (I don't know exactly how a new moon is defined, as
you'll see) moon is almost coincident with the Sun, and so rises and
sets with it.

Believe it or not, that's only just occurred to me - amazing what
retirement can do.

So it's obscured by the sun's glare, and not illuminated.

As it moves away from the Sun, there will be an illuminated crescent,
but first it will be very tiny, and close to the Sun.

So the question is, at what (angular) distance from the Sun can I expect
the moon to have a visible crescent _and_ be far enough away in
degrees to be visible against the Sun, and distant in time to set (rise
for an old moon - I theeeenk), so that it could be expected to be
observed.

And is there an official definition that agrees with practical
observational factors (or doesn't)

Thanks for any enlightenment

mike

JRS: In article 0,
seen in news:uk.sci.astronomy, mike ring
m posted at Tue, 18 May 2004 21:46:19 :

So the question is, at what (angular) distance from the Sun can I expect
the moon to have a visible crescent _and_ be far enough away in
degrees to be visible against the Sun, and distant in time to set (rise
for an old moon - I theeeenk), so that it could be expected to be
observed.

For a considered answer, consult the Imam of your nearest reputable
Mosque. Tomorrow is the first day of Rabi'II 1425 AH, according to
Saudi Arabian Airlines.

For an alternative (and longer-considered) answer, try the Rabbi of your
local synagogue. By chance, the first day of Pesach this year (15 Nisan
5764 AM) fell on the first day of the UK financial Year, from which I
suppose that the month of Sivan 5764 is about to start.

It may be unwise to attempt to consult them simultaneously; their Lunar
Calendar definitions are unlikely to agree.


And is there an official definition that agrees with practical
observational factors (or doesn't)

There are a number of them. One is, probably, at the JAS site
http://www.jas.org.jo/sau.html. I suggest looking at
http://www.heavens-above.com/ for something easier to read; but I've not
checked whether they have it.

The practical answer will depend on local conditions; a thin crescent
moon just visible around sunset in desert conditions will be lost in the
murk hereabouts.

IIRC, the answer is in the region of 36-48 hours; but ICBW.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc : URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

"CLT" not@thisaddress wrote in :

http://skyandtelescope.com/observing...cle_1173_1.asp

Thanks very much, CLT, just the job,

(goes away for a good read)

mike

In article , Dr John Stockton
writes

For a considered answer, consult the Imam of your nearest reputable
Mosque. Tomorrow is the first day of Rabi'II 1425 AH, according to
Saudi Arabian Airlines.


Coincidentally, there was a partial solar eclipse on 25th December 2000
(our calendar), which fell towards the end of the Islamic holy month of
Ramadan and the start of the new month. I was curious to know if the
visible conjunction had any impact on the Islamic calendar and posed the
question in the newsgroup uk.religion.islam. I received the following
response from Anjum Jaleel, posting from the USA. This indicates that it
did not, but there is some debate, within the religion of Islam, as to
what constitutes a new Moon.

The partial eclipse has nothing to do with signifying the end of a
lunar month. It depends on the new moon. Currently, there is a debate
between good Muslims on what constitutes 'the new moon'. Some good and
well-meaning Muslims feel that we now have the technology to tell if
the new moon is dying to be seen behind the clouds, which are not that
far high, while other, equally good and well-meaning Muslims believe
that we must 'see' the moon with our naked eyes, as was done at the
Prophet's time. [A note of clarification: If the new moon is not 'seen'
on the 29th day of the month, the month is extended for one more day,
ie., the 30th is the final day of the month whether or not the moon is
'seen' that day]


Hopefully, these two groups of pious Muslims would come to an agreement
in the future and we will have one Eid in each of our local communities
on a regular basis.


--
David Entwistle

In message , Dr John Stockton
writes
JRS: In article 0,
seen in news:uk.sci.astronomy, mike ring
m posted at Tue, 18 May 2004 21:46:19 :

So the question is, at what (angular) distance from the Sun can I expect
the moon to have a visible crescent _and_ be far enough away in
degrees to be visible against the Sun, and distant in time to set (rise
for an old moon - I theeeenk), so that it could be expected to be
observed.

For a considered answer, consult the Imam of your nearest reputable
Mosque. Tomorrow is the first day of Rabi'II 1425 AH, according to
Saudi Arabian Airlines.

But isn't the Saudi calendar at variance with most Islamic calendars?
(and the site I checked first about this
http://www.phys.uu.nl/~vgent/islam/mecca/ummalqura.htm thanks you for
correcting some errors :-)
BTW, what happened to the regular Hilal posting on sci.astro?
--
Save the Hubble Space Telescope!
Remove spam and invalid from address to reply.

mike ring wrote:
So the question is, at what (angular) distance from the Sun can I
expect the moon to have a visible crescent _and_ be far enough away
in degrees to be visible against the Sun, and distant in time to set
(rise for an old moon - I theeeenk), so that it could be expected to be
observed.

The graphic at the top of http://www.hilal-sighting.com/ should answer
your questions.

Best,
Stephen

Remove footfrommouth to reply

--
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Stephen Tonkin wrote in
:

mike ring wrote:
So the question is, at what (angular) distance from the Sun can I
expect the moon to have a visible crescent _and_ be far enough away
in degrees to be visible against the Sun, and distant in time to set
(rise for an old moon - I theeeenk), so that it could be expected to
be observed.

The graphic at the top of http://www.hilal-sighting.com/ should answer
your questions.

That's an interesting picture, Stephen and makes sense, but I can't work
out what the elong-impos curve means.

CLT's reference was also very helpful, and established that I mught have
seen a new moon the night of his answer, and would have done the
following night if it hadn't been cloudy.

Tonight....?

However the thread was informative and also went straight to the nub of
my question, so thanks to all

mike

JRS: In article , seen in
news:uk.sci.astronomy, David Entwistle
posted at Thu, 20 May 2004 16:04:27 :
In article , Dr John Stockton
writes

For a considered answer, consult the Imam of your nearest reputable
Mosque. Tomorrow is the first day of Rabi'II 1425 AH, according to
Saudi Arabian Airlines.


Coincidentally, there was a partial solar eclipse on 25th December 2000
(our calendar), which fell towards the end of the Islamic holy month of
Ramadan and the start of the new month. I was curious to know if the
visible conjunction had any impact on the Islamic calendar and posed the
question in the newsgroup uk.religion.islam. I received the following
response from Anjum Jaleel, posting from the USA. This indicates that it
did not, but there is some debate, within the religion of Islam, as to
what constitutes a new Moon.

The Moon's path across the sky varies by 5 degrees peak from that of the
Sun, and the Sun sets at a slant. For the New Moon to be visible at in
the evening, it must be far enough from the Sun and above the effective
horizon. ISTM that am observation-based or well-calculated Islamic
Calendar can thus be affected by the Moon-Sun path difference near
Sunset. The eclipse shows that the path difference, that day, was
insignificant.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc : URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

JRS: In article , seen in
news:uk.sci.astronomy, Jonathan Silverlight
snet.co.uk.invalid posted at Thu, 20 May 2004 23:19:38 :
In message , Dr John Stockton
writes
JRS: In article 0,
seen in news:uk.sci.astronomy, mike ring
m posted at Tue, 18 May 2004 21:46:19 :

So the question is, at what (angular) distance from the Sun can I expect
the moon to have a visible crescent _and_ be far enough away in
degrees to be visible against the Sun, and distant in time to set (rise
for an old moon - I theeeenk), so that it could be expected to be
observed.

For a considered answer, consult the Imam of your nearest reputable
Mosque. Tomorrow is the first day of Rabi'II 1425 AH, according to
Saudi Arabian Airlines.

But isn't the Saudi calendar at variance with most Islamic calendars?

That's why I gave two sources in that paragraph.

Giving the day of the week, in our terms, should resolve ambiguity.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.