THE SOUTHWORTH PLANETARIUM
207-780-4249   www.usm.maine.edu/planet
70 Falmouth Street   Portland, Maine 04103
43.6667° N                   70.2667° W 
Altitude:  10 feet below sea level
Founded January 1970
Julian date: 2458757.5
2019-2020:  XXII
             "More organized than Brexit."


THE DAILY ASTRONOMER
Wednesday, October 2, 2019
October 2019 Night Sky Calendar   Part II

SUNDAY, OCTOBER 20:  MERCURY AT GREATEST EASTERN ELONGATION
This is the best time to see Mercury.   One will find the elusive little planet over in the western evening sky this week.   Tonight, Mercury's solar elongation angle will be 25 degrees east.  When an inferior planet is east of the Sun, it will be visible in the western evening sky.  When it is west of the Sun, it will be visible in the eastern pre-dawn sky.
____________________________________________
"MOON NEAR THE BRIGHT STARS" OCTOBER TIMETABLE
The moon will often appear to move close to (and sometimes
occult) four first magnitude stars:  Aldebaran (Taurus the Bull),
Antares (Scorpius the Scorpion), Regulus (Leo the Lion),
and Spica (Virgo the Maiden).     Each month we'll include
this time table to inform you about when the moon will
be close to each of these stars.  If the passage produces
an occultation from our perspective, we'll provide more information.

Spica, Virgo's brightest star, is so close to the Sun that it won't be included
in this month's timetable

OCTOBER 3:  ANTARES  (waxing crescent moon)

OCTOBER 17: ALDEBARAN (waning gibbous moon)

OCTOBER 23:  REGULUS (waning crescent moon)

OCTOBER 30:  ANTARES (waxing crescent moon)

Notice that Antares appears close to the moon twice this month.
Only 27 days separate these successive appulses because Antares
position relative to the Sun is changing by virtue of Earth's motion
around the Sun.
__________________________________________________

MONDAY, OCTOBER 21:  LAST QUARTER MOON

MONDAY, OCTOBER 21:  ORIONID METEOR SHOWER PEAKS (GOLD EVENT!!!)
Halley's Comet returns to Earth's sky in 2061.  Presently, it is moving lethargically away from the Sun along its outer orbit. This famous interplanetary interloper reaches aphelion in December 2023, at which point it will turn around and move slowly back toward the inner solar system.      Those who are eager to behold this comet must wait a few more decades before its return.  However, they can still see pieces of Halley's comet now:  these fragments are currently infiltrating our atmosphere to produce the Orionid meteors.    Named for the constellation from which they appear to emanate, the Orionid meteor shower begins on October 2 and ends of November 7th.  During that nearly five week stretch, Earth is moving through a vast field of meteoroids that Halley's comet emitted during its multiple sojourns close to the Sun.     During these close approaches, the Sun's heat causes Halley's ices to sublimate: change from solid directly to vapor.  The dust embedded within the comet scatters along its orbital path.      When Earth ploughs through this region, these meteoroids, as they're known when they're in outer space, descend through the atmosphere.  The resultant heating excites nearby atoms, elevating their electrons to higher energy levels.  These electrons emit light when they settle down to their original energy states.  These are the lights that we perceive as meteors.   

Orionid_radiant_new_f.jpg
RADIANT:  the apparent convergence point of the Orionid meteors is located within the Orion region, hence the name.   Remnants of Halley's Comet produce the lights we see as the Orionids. These meteors tend to move very quickly, their speeds often exceeding 80,000 miles per hour.

Tonight, one might observe 20 - 40 meteors an hour.     The best time to observe any meteor shower is after midnight, around the time the last quarter moon rises.    Although the lunar light interference will obscure some of the meteors, the Orionids should still prove to be something of a late night spectacle for those who opt to venture outside after the witching hour.

SATURDAY, OCTOBER 26: PERIGEE MOON
The moon reached apogee, its greatest distance from Earth, on October 10th. Today, the moon reaches perigee, its point of least distance.    Today, the moon's minimum distance will be 361,311 kilometers.  As the perigean moon occurs around the New Moon (Oct 27), we can expect unusually high tides today.   However, as the moon will appear as a razor thin crescent, there won't be much to see.

Note: the moon will be near Mars tonight, but as both are virtually impossible to observe, the close encounter scarcely warrants a mention.

SUNDAY, OCTOBER 27:  NEW MOON
Start of lunation cycle 1198

MONDAY, OCTOBER 28:  URANUS AT OPPOSITION
No, we really can't observe Uranus without at least a set of binoculars.  True, some show offs insist that they can see Uranus with the unaided eye.  Of course, those keen-eyed observers are watching the heavens the deepest wilderness and they also precisely know Uranus' position.  We mortals, however, will only know that Earth passes between the Sun and Uranus today.    At this time, Uranus will be at its closest (1.74 billion miles) and at its brightest, barely above naked eye visibility range.  Including the opposition dates of the remote planets does remind us of all that is transpiring in the unseen depths of deep space.

TUESDAY, OCTOBER 29:  MOON NEAR VENUS (BRONZE EVENT!)
Early this evening one will observe the thin, waxing crescent moon (3% illuminated) "close" to the brilliant planet Venus.    This coupling will produce one of the month's truly gorgeous spectacles as both worlds will be immersed in twilight.  Moreover, the moon will actually appear spherical owing to the dusk coloration and the Earth-shine (reflection of sunlight on Earth cast onto the dark parts of the moon) that will enable observers to see the entire lunar disk. 

THURSDAY, OCTOBER 31: MERCURY 2.6 DEGREES SSW OF VENUS (SILVER EVENT!!)
Find Mercury and Venus in the western evening sky tonight.   One will experience no difficulty distinguishing between them as Venus will be 57 times brighter than Mercury.  Of course, Venus has the advantages of being closer to Earth than Mercury.  Venus also has six times the surface area of Mercury and reflects a lot more sunlight due to its pervasive cloud cover.  
Whereas Venus reflects about 67% of all sunlight back into space, Mercury only reflects about 6%, about the same as the moon.     Both planets will set within an hour of sunset, however, so venture out early to see them,

PLANET WATCH

MERCURY:  October is a splendid month for Mercury, at least toward the end of the month.   Look for Mercury in the westen evening sky this month.  VERDICT: The last ten days of October provide the best opportunity to see this little planet.  It will be at greatest elongation on October 20th and close to Venus on Halloween.

VENUS: Venus and Mercury share the western evening sky stage this month!  Although Venus will naturally be the brighter planet, both worlds will capture your attention,   VERDICT: Venus will rise higher throughout the autumn and become quite an evening sky spectacle by year's end.    If you miss it in October, you'll have plenty of opportunities to see it later in 2019.

MARS: Now is the time to start watching Mars.  It is true that Mars lurks low in the eastern pre-dawn sky this month.  However, the red world will be rising earlier, growing brighter and becoming redder throughout the next twelve months as Earth and Mars draw closer together.  VERDICT:   Mars returns, but is difficult to see until later this autumn.     No worries if you miss Mars this month.

JUPITER (PICK PLANET).  Jupiter is October's pick planet because it is the bright "star" one will see in the western evening sky.  This giant world will appear to approach the setting Sun each night.  By the first of December, it will be quite low and before the year's end, it will vanish into the dusk, only to return to the pre-dawn sky early in 2020.    VERDICT:  Find Jupiter while you can!    It is still easy to find in the early evening.

SATURN:  Well, yes, we hate you, Saturn.  We always pay more attention to your brighter older brother Jupiter and consistently give you short shrift each month.  Yes, you're in the evening sky, too. Although you'll be up later than Jupiter, you're dimmer, harder to find and therefore woefully under appreciated by us humans who esteem appearances far too highly.  Yes, you have those nifty rings which you wear ostentatiously to compensate for your perceived deficiencies, but it is of little matter as you are so far away from us and, unlike the repentant prodigal, will never move closer to us in spite of your deep, ardent and unexpressed desire for greater intimacy.   VERDICT:  Oh, who cares!



TO SUBSCRIBE OR UNSUBSCRIBE FROM THE "DAILY ASTRONOMER" LIST-SERVE: