THE SOUTHWORTH PLANETARIUM
70 Falmouth Street      Portland,Maine 04103
(207) 780-4249      usm.maine.edu/planet
43.6667° N    70.2667° W  Altitude:  10 feet below sea level Founded
January 1970
2021-2022: XXIII
"In dreamless sleep, we return to the source: to the life force that
animates every living thing. Space collapses, time ceases to exist and we
no longer interact with the cosmos as discrete beings. Instead, we mingle
with the infinite and experience the eternal as it truly manifests itself,
as the absence of temporal flow. In that suspended state no disturbance is
possible. We know only the serene breathings of a living Universe that each
night bestows on us the rejuvenation of body and the rebirth of spirit."

THE DAILY ASTRONOMER
Monday, October 4, 2021
October 2021 Night Sky Calendar
Part I
A Sky of Simple Shapes

____________________________ A format change to our calendar
We will continue to post the night sky calendar in multiple parts.
However, the first part will be an overview of the sky, including
information pertaining to constellations and other night sky features.
The second part and any of those subsequent to it, will feature the events
listed by day.
_____________________________

Describing celestial body positions presents a particularly difficult
challenge to those who write about it.  One must try to communicate
locations using degrees, directions and other night sky "landmarks" (a
funny term) in the hope that the reader will easily locate a given object
or objects.    At times, as in early autumn, the task is rendered easier
because one should be able to readily find the sky's most prominent
features.

First  of all, as soon as darkness descends, look straight up.   There, in
the zenith region, one will find the Summer Triangle.

[image: c0295854-summer_triangle_in_the_milky_way_web.jpg]

So named as it remains visible throughout most of the night in the summer,
the Summer Triangle is actually easiest to find now. Again, simply look up
in the early evening. The three stars comprising it, Deneb, Vega and
Altair, seem as though they are adjacent to each other. This apparent
proximity is illusory, a result of the way our sky conceals depth. In fact,
immense tracts of interstellar space separate them. Altair is approximately
17 light years away. Vega's distance is 26 light years. Deneb, however, is
1000 times more distant: 2,612 light years away. Consequently, when one
observes these stars, one is seeing them as they were in the past. Tonight,
one sees Altair as it was in 2004. To look onto Vega is to see it as it was
in 1995. Deneb appears to us tonight as it was in the 6th century BCE,
around the time when Pythagoras of Samoa, the world-renowned mathematician
best known for the theorem that still bears his name.*

Dark-sky observers might detect the faintly luminescent band that appears
to flow through this triangle. That light is the "Milky Way," an edge on
view of our home galaxy. The name is somewhat misleading because every
single naked eye star is contained within our home galaxy. However, the
"Milky Way" defines the region of highest stellar density: where one finds
more stars per unit area than in any other sky region.

[image: Milky-Way-face-on-edge-on-NASA-S.jpg]

Remember as you admire the sky that we're all traveling through the galaxy
at 143 miles per second.  Our solar system is located approximately 25,000
light years from the nucleus.   Like the majority of stars, the Sun is
moving along the main disc, part of which we see when we look at the Milky
Way band.     The stars located far from the band are either located
"north," or "south" of the galactic plane.

Just east of the Summer Triangle one will find another simple shape, the
Great Square of Pegasus.   The square represents the body of Pegasus, the
elegant winged horse who was born out of Medusa's blood and eventually
tamed by Bellerophon who rode on Pegasus' back when he slew the Chimera.
 Pegasus is depicted as flying upside down, a reference to Bellerophon's
audacious attempt to fly Pegasus up to Olympus.   The winged horse
prudently refused to ascend to such an exalted height and turned herself
over.  This sudden inversion caused Bellerophon to plummet to his death
after a descent requiring seven days and seven nights.

[image: Perseus-Constellation-Family-1280x720.jpg]

Just to the north of Pegasus one will find Cassiopeia, a *circumpolar
constellation *resembling the letter "w."  A circumpolar constellation is
one that doesn't set at our latitude.   Cassiopeia represents an ancient
Ethiopian queen poised on her throne.    Notorious for her appallingly
supercilious behaviour, Cassiopeia was hoisted up into the sky as a
punishment for she must suffer the indignity of hanging upside down for at
least half the night.

The last simple shape, the Big Dipper, begins the night resting on the
horizon. Even though it, too, is circumpolar,the Big Dipper might be hidden
from view by houses ,trees or other obstructions.

[image: e4035b780c8769feb021006774f5b840--ursa-major-big-dipper.jpg]

These simple shapes will hopefully help an observer find his/her way around
the early evening sky.

Part II of the October 2021 Night Sky calendar tomorrow.
*
[image: 1_SsN2DG__Z5DyOI0uf7hbwQ.png]

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