THE SOUTHWORTH PLANETARIUM
70 Falmouth Street      Portland, Maine 04103
(207) 780-4249      usm.maine.edu/planet
43.6667° N    70.2667° W  Founded January 1970
2022-2023: LXIV
Sunrise: 6:18 a.m.
Sunset: 5:29 p.m.
Civil twilight begins: 5:49 a.m.
Civil twilight ends: 5:58 p.m.
Sun's host constellation: Aquarius
Moon phase: Waxing gibbous (74% illuminated)
Moonrise: 11:35 a.m.
Moonset: 4:07 p.m.
Julian date: 2460005.29 "Behind every beautiful thing there is some kind of
pain."
-Bob Dylan

THE DAILY ASTRONOMER
Wednesday, March 1, 2023
March 2023 Night Sky Calendar:  Stars on Parade

Whew!
We're back!  Hastily disinterred.  Yanked away from Calypso's enveloping
embrace.  Propelled back up from the tenebrous depths of the Hadopelagic
zone.   Unwrapped, unfolded, smoothed out, steam cleaned, corners
iron....yes, yes, yes. we're back and we just couldn't be happier to see
you.        Barring any unforeseen circumstance, the DA should not go into
a protracted hiatus again..apart, of course, from those we
regularly schedule, anyway.    Thanks to the BWA for holding down the
fortress in our absence.

Now, let's just get on with it.

*THOSE BRIGHT WESTERN 'STARS!'*
are not stars at all, but you might have realized that fact already.  Those
brilliantly bright and beguilingly beautiful orbs are none other than
Jupiter and Venus!  The latter always outshines all other celestial objects
apart from the Sun and moon.  The former is quite often the second
brightest planet. Presently, Venus is approximately six times brighter than
Jupiter, so one should experience no difficulty distinguishing between
them.   It's a delight to the eyes when Zeus and Aphrodite flit about and
co-mingle.  These worlds will come within 0.5 degrees of each other
tonight.

*FOLLOW THE LION*
That our remote forebears relied at least in part on the constellations to
keep track of the seasons is hardly surprising.  Even in our modern era of
grandfather clocks and graduated time candles, the constellations still
emerge in the eastern pre-dawn and vanish into the western dusk with
pleasingly perfect regularity.        For instance, we can keep our
admiring eyes fixed firmly on Leo the Lion over the next few months.  In
early March, this nasty Nemean menace starts its eastern sky ascent
after sunset and remains visible throughout the night.  However, as we
trudge glacially through spring and then sprint madly through early summer,
Leo will draw inexorably toward the setting Sun.        By early August,
Leo's luxuriant mane and heart star Regulus will dissolve into the dusk.
By mid August,  the Sun will move into the  Leo the Lion constellation
rendering it temporarily invisible.      From now until early August, an
observer can use Leo the Lion to follow our seasonal transition from biting
cold to gnawing cool to lightly chilled to curiously warm to fleetingly
hot.

[image: Leo-the-Lion-1.jpg]

*ORION'S RULE*
Venture outside just as darkness descends and you'll observe Orion moving
along the meridian, the imaginary arc connecting north and south.    This
lusty, violence-prone bane to all creatures great and small remains
prominent in our evening night sky.     As Orion is arguably the most
famous of all constellations by virtue of his array of bright stars
and uncanny resemblance to an enormous human, many observers understandably
want to know his location throughout the year.       Fortunately, because
of the regularity of the annual constellation motions caused by Earth's
orbital motion around the Sun, Orion tracking is a rather straight-forward
matter provided that one knows Orion's Rule, or the 'Two Hour Rule.'
First, remember that all stars which are not circumpolar rise four minutes
earlier each day as a consequence of Earth's changing position relative to
the Sun.   This difference amounts to about half an hour a week or two
hours each month.         On February 1, Orion is due south at 8:00  p.m.
     Using the Orion Rule, we can therefore conclude that Orion will be due
south at 6:00  p.m. on March 1st and at 10:00 p.m. on January 1st.      Oh,
heavens, we're so full of pep and ginger at present, let's just go through
the whole year:

Orion will be due south at

   - 10:00 p.m.  on Jan 1
   - 8:00 p.m.  on Feb 1
   - 6:00 p.m. on Mar 1
   - 4:00 p.m. on Apr 1
   - 2:00 p.m. on May 1
   - 12:00 p.m. on June 1
   - 10:00 a.m. on July 1
   - 8:00 a.m. on Aug 1
   - 6:00 a.m. on Sept 1
   - 4:00 a.m. on Oct 1
   - 2:00 a.m. on Nov 1
   - 12:00 a.m. on Dec 1

Orion's belt, consisting of the stars Mintaka, Alnilam, and Alnitak, is
aligned just south of the celestial equator and so remains in the sky for
approximately 12 hours each day.        Bearing this fact in mind, we know
that Orion's belt  rises six hours before it is due south and sets six
hours after it's due south.     On February 1st, then, Orion's belt rises
around 2:00 p.m. and sets around 2:00 a.m.     So, one will find Orion
ascending in the eastern sky between the times of first darkness and 8:00
p.m. on February 1st and then will watch this broad-chested behemoth of a
bunny-basher descending through the west until 2:00 a.m.   Orion's two
shoulder stars Betelgeuse and Bellatrix, both of which are a bit less than
ten degrees north of the celestial equator, remain above the horizon for
about 12.5 hours. The knee stars, Rigel and Saiph, are at about the same
angular distance south of the celestial equator and so remain above the
horizon for 11.5 hours.

[image: 240_F_230951676_JeYxkfXKa11wHuEFaRSYGxmVKvAqUCoe.jpg]

Finally, we realize that Orion vanishes into the dusk in  mid-May only to
return to the eastern pre-dawn sky in early August.    Within this time
frame, Orion is not visible.  Otherwise, one can use the Orion Rule to seek
out this celestial hunter at any other time of year.

Tomorrow, the actual calendar.


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