Universe Today
Do you welcome the extra evening light of the Full Moon, or curse the additional light pollution? Either way, this week's Full Moon on Friday April 22
nd
is special. It's the smallest Full Moon of 2016, something we here at
Universe Today
have christened the Mini-Moon.
Mini-Moon 2016: This year's
Mini-Moon falls
on April 22
nd
at 5:25 Universal Time (UT), just 13 hours and 19 minutes after lunar apogee the evening prior at 16:06 UT on April 21
st
. Though apogee on the 21
st
is 406,350 km distant – a bit on the far end, but the third most distant for the year by 300 km — this week's Full Moon is the closest to apogee for 2016 time-wise. The 2015 Mini-Moon was even closer, in the 10 hour range, but you'll have to wait until December 10
th
, 2030 to find a closer occurance.
[caption id="attachment_128479" align="alignnone" width="580"]
The Mini-Moon versus the 2011 Supermoon. Image credit and copyright:
Ken Lord
.[/caption]
What is the
Mini-Moon
, you might ask? As with the often poorly defined Supermoon, we like to eschew the ambiguous '90% of its orbit' definition, and simply refer to it as a Full Moon occurring within 24 hours of lunar apogee, or its farthest point from the Earth in its orbit.
Fun fact: the 29.55 day period from perigee to perigee (or lunar apogee-to-apogee) is known as an anomalistic month.
[caption id="attachment_128481" align="alignnone" width="580"]
Mini-Moons by year for the remainder of the decade. Note that the 2020 Full Moon is also the 2nd of the month... A 'Mini-Blue Halloween Moon?' Image credit: Dave Dickinson[/caption]
Thank our Moon's wacky orbit for all this lunacy. Inclined 5.14 degrees relative to the ecliptic plane, the Moon returns to the same phase (say, Full back to Full) every 29.53 days, known as a synodic month. The
Moon can appear
33.5' across during perigee, and shrink to 29.4' across near apogee.
[caption id="attachment_128477" align="alignnone" width="450"]
The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size.
Wikimedia Commons
graphic in the Public Domain.[/caption]
And don't fear the 'Green Moon,' and rumors going 'round ye' ole internet that promise a jaded Moon will occur in April or May; this is 100% non-reality based, seeking to join the legends of Super, Blood, and Full Moons,
Black and Blue
.
[caption id="attachment_128480" align="alignnone" width="580"]
No. Just. No. Image faked by: David Dickinson.[/caption]
The April Full Moon is also known as the
Full Pink Moon
to the Algonquin Indians. The April Full Moon, can, on occasion be the
Full Moon ushering in Easter
(known as the Paschal Moon) as per the rule established by the 325 AD council of Nicaea, stating Easter falls on the first Sunday after the first Full Moon after the fixed date of the Vernal Equinox of March 21
st
. Easter can therefore fall as
late as April 25th
, as next occurs on 2038. The future calculation of Easter by the Church gets the Latin supervillain-sounding name of
Computus
.
[caption id="attachment_128482" align="alignnone" width="580"]
Looking east on the evening of April 21st. Image credit: Stellarium[/caption]
Of course, the astronomical vernal equinox doesn't always fall on March 21
st
, and to complicate matters even further, the Eastern Orthodox Church uses the older Julian Calendar and therefore, Easter doesn't always align with the modern western Gregorian calendar used by the Roman Catholic Church.
The Moon can create further complications in modern timekeeping as well.
Here's one wonderful example we recently learned of in our current travels. The
Islamic calendar
is exclusively based on the synodic cycle of the Moon, and loses 11 days a year in relation to the Gregorian solar calendar. Now, Morocco officially adopted Daylight Saving (or Summer) Time in 2007, opting to make the spring forward during the last weekend of March, as does the European Union to the north. However, the country reverts back to standard time during the month of Ramadan... otherwise, the break in the daily fast during summer months would fall towards local midnight.
You can see a curious future situation developing. In 2016, Ramadan runs from sundown June 5th, to July 4th. Each cycle begins with the sighting of the thin waxing crescent Moon. However, as Ramadan falls earlier, you'll get a bizarre scenario such as 2022, when Morocco springs forward on March 27th, only to fall back to standard time six days later on April 2
nd
on the
start of Ramadan
, only to jump forward
again
one lunation later on April 30th!
Morocco is the only country we've come across in our travels that follows such a convoluted convention of timekeeping.
Fun fact #2: the next
'Mini-Moon' featuring a lunar eclipse
occurs on July 27
th
2018.
And the Spring Mini-Moon sets us up for Supermoon season six months later this coming October-November-December. Though
lunar perigees
less than 24 hours from Full usually occur as a trio, an apogee less than 24 hours from Full is nearly always a solitary affair, owing to the slightly slower motion of the Moon at a farther distance.
Don't miss the shrunken Mini-Moon rising on the evenings of Thursday April 21
st
and Friday 22
nd
, coming to a sky near you.
