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Moon Applet
| Month | Date | Year | UT |
 |
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Use
the key "d" to increase the date, or shift key and "d" to decrease the
date,
use
the key "y" to increase the year, or shift key and "d" to decrease the
year,
click into the applet first !
The
planet name in brackets following the date is the ruler of the day.
The Golden Number of a
year is its remainder after division by 19, plus 1.
The
epact is defined as the
age of the moon on January 1 in days (since an
"official" new moon),
which may be different from the "true" (astronomical) age of the moon.
How to
compute
the date of Easter by the epact.
Use the Data button to show the New Moon or Full Moon times and lunations for the year selected:
The
mean
error of the New Moon and Full Moon times for 2004 and
2005
compared to the times by USNO is less than 2 minutes.
More
Moon
applets:
Azimuth of the Sun and the Moon at rise or set Longitude and
orbit of the Moon More
details:
Diagram
of time intervals between consecutive New Moons (duration of the
lunation)
for 2004,
January to 2025, September.
The mean value of 269 lunations is 29.5295 days.
The mean value for a long time is 29.530589 days = 29 days 12 hours 44 minutes 03 seconds (synodic month).
Extreme
lunations:
Moon
apogee
Dec
25,
Jan
28 Moon
perigee
Jun
06,
Jul
04
to 1974, Jan 23, 11:04 UT
= 29 d 12 h 44 m + 7 h 12 m
Earth perihelion Jan 04
to 2035, Jul 05, 10:02 UT
= 29 d 12 h 44 m - 6 h 04 m
Earth aphelion Jul 05
The
variation
is
due
to
the
excentricity
of
the
Earth's
orbit.
The
lunation
will
have
its
greatest possible duration when, at the instant
of New Moon, the Moon is near its apogee and the Earth is near its
perihelion. The shortest possible lunation will take place
about six months earlier or later, when at New Moon the Moon is near
perigee and the Earth near aphelion. There is a period 8.85 years.
A
detailed discussion:
Jean Meeus: More mathematical Astronomy Morsels, Willman-Bell, 2002,
ISBN 0-943396-74-3
Earth-Moon and Sun-Earth distances
There
is
a
periodicity
of
19
years
(Metonic Cycle): 235
lunations
=
235
*
29.530589
days
=
6
939.688
days with
an
error
of
0.086
days
(2
h
4
min). The
19-year
cycle
is
also
close
(to
somewhat
more
than
half
a
day)
to
255
draconic
months,
so
it
also
is
an
eclipse cycle.
19 tropical years = 19 * 365.24219 days = 6 939.602 days
Diagram
of time intervals between consecutive Full Moons (duration of the
lunation)
for 2004,
January to 2025, September
(computed by Planet
Applet)
Diagram
of time intervals between consecutive ascending node passages
(draconic month)
for 2004, January to 2024, December (computed by Planet
Applet)
The mean value of 284 ascending node passages is 27.2133 days.
The Saros Cycle:
Synodic
Month
(New
Moon
to
New
Moon) 29.53059
days
=
29d
12h
44m Draconic
Month
(node
to
node)
27.21222
days
=
27d
05h
06m 223
Synodic
Months 223
*
29.53059
d
=
6585.32
d
Å
18
years
10
or
11
d
8
h 242
Draconic
Months 242
*
27.21222
d
=
6585.35
d
Å
18
years
10
or
11
d
8
h
Any two eclipses separated by one Saros Cycle share very similar geometries.
Diagram
of time intervals between consecutive perigees (anomalistic
month)
for 2004, January to 2025, September (computed by Planet
Applet)
The mean duration of 284 anomalistic months is 27.555 days.
Perigee distances:
The mean perigee distance of 284 anomalistic months is 362562.4 km.
Ecliptic
latitude
of
the
Moon
2005
to
2007
the
time axis is: Julian day - 2453000
Local transit elevation of subsequent Full Moons, Berlin, 2005-2007
The lowest-hanging full moon in 18 years: 2005, June 21
A
Blue Moon is the second full moon in a calendar month.
Usually months have only one full moon, but occasionally a second one
sneaks in. Full moons are separated by 29 days, while most months are
30 or 31 days long; so it is possible to fit two full moons in a single
month. This happens every two and a half years, on average.
Distance
of the Full Moon from the Earth
Last Modified: 2010, May 08