THE SOUTHWORTH PLANETARIUM
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43.6667° N    70.2667° W  Altitude:  10 feet below sea level Founded
January 1970
2021-2022: IV
"Serious things cannot be understood without laughable things, nor
opposites at all without opposites."
-Plato


THE DAILY ASTRONOMER
Tuesday, September 7, 2021
September 2021 Night Sky Calendar Part II

*SATURDAY, SEPTEMBER 11, 2021: SOUTHERN TAURID METEOR SHOWER BEGINS*
Meteor showers are often believed to be fleeting events, often occurring
over a period of 1 - 3 nights. Actually, meteor showers often last weeks.
These showers occur when Earth passes through a wide debris field left
behind usually by comets and occasionally by asteroids. These fragments,
known as *meteoroids*, often infiltrate the atmosphere at high velocity.
The resultant excitation of surrounding atoms produces the momentarily
light flash we perceive as meteors. A meteor shower "peaks" when Earth
moves through a more dense region of this debris field. For instance,
people tend to watch out for Perseid meteors around August 11/12, the
typical peak date. However, the Perseid meteor shower begins around July
17th and ends around August 25th, equal to the time Earth requires to
travel completely through the remnants of Comet Swift-Tuttle, the Perseids'
parent body. The Southern Taurid, and its "twin" shower, the Northern
Taurid - which begins on October 20- has a "weak peak," that produces
approximately 5 meteors an hour. Considering that an observer could see 6 -
10 meteors an hour on any night due to sporadic meteors, those not
associated with a specific parent body, the Southern Taurids hardly garner
much press coverage. That Southern Taurid peak, incidentally, occurs on
October 10th.
[image: TauridsARTv2.jpg]
The Southern Taurid shower is so named because the *radiant*, the point
from which the shower's meteors appear to emerge, is located within the
southern region of Taurus the bull.   Most meteors are named for the
constellation in which their radiant is located.
*SUNDAY, SEPTEMBER 12, 2021:  MOON NEAR ANTARES*
Yesterday, we mentioned that the moon and the planets travel along a band
centered on the ecliptic.  Consequently, the moon and planets are able to
move through the zodiac constellations.   They can also move close or
sometimes even occult (move in front of) some bright stars within those
zodiac constellations.    The four brightest "ecliptic stars" are Aldabaran
(Taurus the Bull), Antares (Scorpius the Scorpion), Regulus (Leo the Lion)
and Spica (Virgo the Maiden). Tonight, the waxing crescent moon (43%
illuminated) will appear to move close to Antares.
[image: MFTo75BD5hwD5DC3bsjPWj.png]
Scorpius the Scorpion: currently visible in the southwestern evening sky
*MONDAY, SEPTEMBER 13, 2021:  FIRST QUARTER MOON  (MOON AT PERIGEE)*
A *supermoon *is defined as a moon that is full while being at or near
*perigee*, its point of least distance from Earth.  A supermoon appears
both 14% larger and 30% brighter than a *micromoon*, or the moon that is
full around the time of apogee, its greatest distance.   As far as we know,
no specific name has been coined for a moon that is at first or last
quarter when at or new perigee.     We welcome your suggestions.
*TUESDAY, SEPTEMBER 14, 2021:  MERCURY AT GREATEST EASTERN ELONGATION *
When at greatest eastern elongation, an *inferior planet*, one closer to
the Sun than Earth, will be at its greatest altitude in the western evening
sky.  Conversely, an inferior planet is at its highest altitude in the
eastern morning sky when at greatest western elongation.     A perfect
night to search for Mercury, which will set around 7:30  p.m.
*FRIDAY, SEPTEMBER 17:  MOON NEAR SATURN*
One will see the waxing gibbous moon (83% illuminated) near Saturn, both of
which will be found within Capricornus the Seagoat.    Both worlds vanish
by 2:30 a.m. the following morning.
*SATURDAY, SEPTEMBER 18:  MOON NEAR JUPITER (BRONZE EVENT!)*
A spectacular sight!  The brilliant planet Jupiter and the waxing gibbous
moon (92%) that looks nearly full.   Observers will see the moon before
sunset, but will have to wait until dusk to see Jupiter.   Both the moon
and Jupiter will remain in sight until around 4:30 a.m.  One important
note:  the moon moves one half degree an hour, which is equal to its
angular diameter.   Watch how the moon's position relative to Jupiter
shifts throughout the night.   Although one cannot directly observe motion
even in the moon, its changing position will be noticeable in reference to
Jupiter which, for all intents and purposes, serves as a fixed point at
least for one night.

*MONDAY, SEPTEMBER 20: FULL MOON (HARVEST MOON!)*
[image: Harvest_Moon_(183115861) (1).jpeg]
Arguably the most famous full moon of the year is the *Harvest Moon, *defined
as the full moon that occurs nearest to the autumnal equinox.    The
Harvest moon can therefore happen as early as two weeks before or as late
as two weeks after the equinox.   Or, it can fall in either September or
October.    The 2021 Harvest moon occurs just before autumn begins.    The
Harvest moon is so named because this full moon provides ample illumination
for farmers so they can harvest their crops at night.  Yes, we do know that
modern-day farmers no longer need this moon as they have ample quantities
of artificial light sources.   All the same, the Harvest moon has retained
the name because it once proved so useful.      Incidentally, the next full
moon after the Harvest Moon is called the Hunters' Moon because that full
moon illuminated the forests and fields where hunters searched for prey.
 And, yes, we do know that modern-day hunters....
Part III  tomorrow
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