Which calendar is correct?

According to hebcal.com,

March 27, 1906 is the 1st day of the Hebrew month of Nisan, which would
be the new moon after the equinox.

April 9, 1906 is Nisan 14, Passover.

See:
http://www.hebcal.com/hebcal/?year=1....cgifields=set


Now, according to the Naval Observatory,

March *24*, 1906 represents the New moon.

See:
http://aa.usno.navy.mil/cgi-bin/aa_m...r=1906&ZZZ=END

Which is correct? Can anyone offer any explanation as to why there's
an offset between the new moon information of hebcal.com and the
Observatory?

On 23 Mar 2006 09:38:07 -0800, "RB" wrote:

According to hebcal.com,

March 27, 1906 is the 1st day of the Hebrew month of Nisan, which would
be the new moon after the equinox.

April 9, 1906 is Nisan 14, Passover.

See:
http://www.hebcal.com/hebcal/?year=1....cgifields=set


Now, according to the Naval Observatory,

March *24*, 1906 represents the New moon.

See:
http://aa.usno.navy.mil/cgi-bin/aa_m...r=1906&ZZZ=END

Which is correct? Can anyone offer any explanation as to why there's
an offset between the new moon information of hebcal.com and the
Observatory?

The Naval Observatory data is correct. Doesn't the Hebrew calendar
define the New Moon based on visibility? After all, when the calendar
was established people didn't know how to calculate exactly when the New
Moon would occur. If so, March 27 sounds about right for a New Moon that
occurred around midnight on March 24/25.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 2006-03-23, RB wrote:
According to hebcal.com,

March 27, 1906 is the 1st day of the Hebrew month of Nisan, which would
be the new moon after the equinox.

April 9, 1906 is Nisan 14, Passover.

See:
http://www.hebcal.com/hebcal/?year=1....cgifields=set


Now, according to the Naval Observatory,

March *24*, 1906 represents the New moon.

See:
http://aa.usno.navy.mil/cgi-bin/aa_m...r=1906&ZZZ=END

Which is correct? Can anyone offer any explanation as to why there's
an offset between the new moon information of hebcal.com and the
Observatory?

The Jewish calendar is based on a calculated lunar cycle, not
the astronomical new moon. The calendrical new moonth is not
necessarily on the date of the astronomical new moon. It's
done that way because the new moon isn't always observable.

--
The night is just the shadow of the Earth.

Thanks for both of your replies. That definitely shines light on it.

JRS: In article .com
, dated Thu, 23 Mar 2006 09:38:07 remote, seen in
news:sci.astro.amateur, RB posted :
According to hebcal.com,

March 27, 1906 is the 1st day of the Hebrew month of Nisan, which would
be the new moon after the equinox.

April 9, 1906 is Nisan 14, Passover.

See:
http://www.hebcal.com/hebcal/?year=1...&o=on&s=on& i
=on&vis=on&D=on&d=on&set=on&heb=on&c=off&geo=zip& zip=&m=72&.s=Get+Calendar&.cgif
ields=nx&.cgifields=nh&.cgifields=set


Now, according to the Naval Observatory,

March *24*, 1906 represents the New moon.

See:
http://aa.usno.navy.mil/cgi-bin/aa_m...r=1906&ZZZ=END

Which is correct? Can anyone offer any explanation as to why there's
an offset between the new moon information of hebcal.com and the
Observatory?

Which Naval Observatory? There are many Navies.

The NO is doubtless reporting the actual New Moon, and may be doing so
in Local Time.

The Hebrew Calendar uses a theoretical approximation to the visible
Moon, in Jerusalem Time.

The Islamic Calendars use different approximations to the visible New
Moon, in Local or Mecca Time IIRC.

One should not expect full agreement between calendars and the Solar
System.


Nisan is not locked to the Equinox, since the average length of the
Hebrew Year is not exactly right; it makes a complete cycle of the
seasons in about 85000 years (the Gregorian Calendar is not locked
either, cycling in around 10000000 years).

URL:http://www.merlyn.demon.co.uk/heb-date.htm and references.

--
© 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.