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: XXIV
Sunrise: 6:42 a.m.
Sunset: 6:17 p.m.
Civil twilight ends: 6:45 p.m.
Sun's host constellation: Virgo the Maiden
Moon phase: Waxing gibbous (68% illuminated)
Moonrise: 4:06 p.m.
Moonset: 1:13 a.m. (10/5/2022)
Julian date: 2459857.21
"Evolution is complexity, but complexity isn't always evolution." -Motto
and guiding principle of the UMS consolidation effort


THE DAILY ASTRONOMER
Tuesday, October 4, 2022
October 2022 Night Sky Calendar Part II

*THURSDAY, OCTOBER 13: MOON NEAR PLEIADES*
[image: tumblr_namlg9pFrc1s030vgo1_1280.jpg]
Poised majestically on the shoulder of Taurus, the Pleiades Star Cluster
seems almost nebulous in appearance.  Yet, on closer scrutiny, one easily
resolves  them  into an ensemble of bright stars.  The beguilingly
beautiful daughters of Atlas pursued tirelessly but in vain by the
lust-crazed Orion, these perpetually youthful sisters dance with bacchanal
abandon throughout the autumn night.     The astronomical Pleiades stars
are scarcely less entrancing than their mythological namesakes.     Freshly
born (120 million years ago) from a long-since abandoned gaseous cloud, the
Pleiades presently travel as a tightly-knit fellowship through the galaxy.
 However, the cohesion will not prove eternal, for their independent
motions will ultimately cause the cluster to disperse as its individual
members follow their own trajectories.    Fortunately, as this dissipation
will require the better part of a billion years, the sisters shall enjoy
each other's company for quite some time to come.
Tonight, Diana's chariot glides just to the south of them.  The waning
gibbous moon (86% illuminated) shines brightly, but will not wholly obscure
the Pleiades.        The cluster and its lunar companion will rise by 8:10
p.m.

*SATURDAY, OCTOBER 15: MOON NEAR MARS*
After having spent a night in the Pleiades' company, Diana might find her
time with the war god to be somewhat less than pleasant.    This time the
chariot flies to the north of Mars while always maintaining a prudent
distance.     See the waning gibbous moon (70% illuminated) close to the
flaming ember eye throughout most of the night.    They rise around 9:30
p.m.    Note that by early morning, the moon's position relative to Mars
will have shifted considerably.

*MONDAY, OCTOBER 17:  LAST QUARTER MOON*

*MONDAY, OCTOBER 17:  MOON AT APOGEE*
Remember yesterday when we discussed the moon's elliptical orbit?
 During each revolution, the moon's distance from Earth varies continuously
between perigee (the closest point) and apogee (the most distant point).
Today the moon reaches apogee and at the precise moment it attains this
maximum distance, it will be 404,328 km (250,683 miles) from Earth.
Unfortunately, we don't yet have a special name indicating a last quarter
moon that occurs on or around apogee.    Suggestions are always welcome.

*FRIDAY, OCTOBER 21: ORIONID METEOR SHOWER PEAKS  (GOLD EVENT!!!)*

[image: November-Orionid-radiant-1.jpg]
The Orionid Radiant: the spot in the sky from which the meteors appear to
originate.  The meteor shower is so named because the radiant is located
within the Orion region.

Let's talk about THIS meteor shower, one of the year's most prominent
meteor events. Our discussion begins with the famous Halley's Comet. Some
subscribers might recall this comet's last visitation in the mid 1980's.
(For many observers, the actual appearance didn't live up to the
20-needles' worth of pre-arrival hype.) Ever since this icy interloper
swooped around the Sun, it has been traveling at progressively slower
speeds toward the outer solar system. (In December 2023, Halley's Comet
will reach aphelion and then turn around for the prolonged journey back
toward the inner solar system.) Like all active comets, when Halley's Comet
ventures close to the Sun, it forms two tails: an *ion tail* consisting of
charged particles repelled by the solar wind and a *dust tail* that forms
when the particles trapped within the comet's surface are liberated by the
sublimating ices*. Those particles create the meteors we observe.

Each year, Earth moves through the particle cloud that formed in Comet
Halley's wake. These particles, properly called *meteoroids*, infiltrate
the atmosphere at high speeds. The descending meteoroid moves so quickly
that it compresses the air along its path. The resultant heating excites
the atoms surrounding the meteoroid. When *excited,* electrons within the
atoms absorb energy and rise to higher energy levels. The excited electrons
quickly return to their original energy states and release light photons.
That light produces the meteors we observe.

The Orion Meteor shower, so named because the meteors appear to emanate
from a region within the constellation Orion, began on October 2 and ends
on November 7th. It peaks today, meaning that today Earth will pass through
the densest part of the meteoroid stream. We can expect 20 - 30 meteors an
hour. The best time to observe these meteors is after midnight, the time
when our part of the planet is turning into the meteoroid stream.

Fortunately, the moon won't interfere with viewing as it will be in the
waning crescent phase (16% illuminated) and won't rise until 2:34 a.m.

Tomorrow, Part III:  Calendar, planets and stars

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