THE SOUTHWORTH PLANETARIUM 207-780-4249   www.usm.maine.edu/planet
<http://www.google.com/url?q=http%3A%2F%2Fwww.usm.maine.edu%2Fplanet&sa=D&sntz=1&usg=AFQjCNHulkHuLP13bOG2PkNrPazsGWFs2A>
70 Falmouth Street   Portland, Maine 04103 43.6667° N
 70.2667° W  Altitude:  10 feet below sea level Founded January 1970 Julian
Date:  2459397.18
2020-2021: CXLVI


THE DAILY ASTRONOMER
Thursday, July 1, 2021
July 2021 Night Sky Calendar  Part I

Happy New Year!
We offer these felicitations because the new fiscal year has started here
at the University.   As our planetarium planetarium is a miniscule outpost
within this grand academic fiefdom, we naturally abide by the same
calendar.   Hence the happy new year bit.     (The new DA school year,
conversely, will begin on September 1.)     As is true with every other
month since months began with the Earth-splintering/moon creating Theia
impact, this month will prove to be breath-stoppingly exciting and shall
offer a rich abundance of retinae-delighting eye confections.
And, as is our wont, we're dividing the calendar into parts.
Let's go!

*THURSDAY, JULY 1:   LAST QUARTER MOON*
What do you mean we're starting the fiscal year with a cough and whimper?
Last quarter moons are far more enthralling that many people believe.
While the full moon garners 98.7% of all the attention, the quarter moons
are beguilingly beautiful in their own rite.   The best time to observe the
quarter moon is when it is rising.   (The July 2021 last quarter moon rises
at 12:32 a.m.)    The ascending moon is steeped in a rich ember glow due to
atmospheric light scattering effects.

[image: 131956298_e988db3815_n.jpg]
We advise all sky watchers to venture outside after midnight to observe the
quarter moon as it peeks above the eastern horizon while progressing from
deep ember to tangerine and then yellow-white.    A perfect way to usher in
the witching hour.

*SUNDAY, JULY 4:   MERCURY AT GREATEST WESTERN ELONGATION*
Are you looking for Mercury?  Well, any Mercury admirer would be well
advised to venture out this morning to find the elusive little planet.
The first world attains its greatest western elongation today and will be
22 degrees from the Sun!      Mercury will rise today at 3:51 a.m, about
ten minutes after the onset of nautical twilight.    At magnitude 0.6,
Mercury will be slightly dimmer than Betelgeuse and so will be bright
enough to observe against the intensifying twilight.

*MONDAY, JULY 5: EARTH AT APHELION*
Why do we have seasons? Some people believe that the seasons relate to the
Earth's changing distance from the Sun.   Summer is hotter because Earth is
closer to the Sun. Winter is colder because we  are farther from the
Sun.    Though wholly logical, that notion is completely wrong.   We have
seasons because Earth is tilted on its axis.  In the summer, our hemisphere
is directed toward the Sun; in the winter, it is oriented away from it.
Distance has little to no effect on our weather at all.  In fact, Earth is
farthest from the Sun (*aphelion)* in early July and closest to the Sun (
*perihelion)* in early January.

[image: main-qimg-5138e4668786da9d4895a1d4d4c42f74.jpg]
This diagram shows Earth's perihelion and aphelion positions.   The orbital
eccentricity (departure from circularity) is highly exaggerated!   The
difference between the perihelion and aphelion distances amounts to little
more than 3 million miles.  (Earth's orbit looks almost circular.)

Today Earth is about 151 million kilometers from the Sun.   After reaching
aphelion, Earth will start to move toward the Sun until reaching perihelion
on January 4, 2022

*TUESDAY, JULY 6:  MOON NEAR PLEIADES*

[image: pleiades-Ernie-Rossi-Florida-e1540922814442.jpg]
We'll see the waning crescent moon (10% illuminated) apparently close to
the Pleiades Star Cluster low in the eastern pre-dawn sky.      The
Pleiades resembles a faint light smudge poised on the shoulder of Taurus
the Bull.

*FRIDAY, JULY 9: NEW MOON*
The beginning of lunation cycle 1219.


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