SEPTEMBER 2014 NIGHT SKY CALENDAR
For those who've just joined, each month begins with a night sky calendar that lists those celestial events we smugly consider noteworthy. The aggravating truth is that each night is rife with such events. Given enough time and ten saints' worth of patience, one could compile all these happenings into a comprehensive report: from satellite passages, International Space Station fly overs, sporadic meteors, aurora events, green flashes, the ancient community of menacing monstrosities, fearsome animals, virtuous paladins, conflicted anti-heroes, galactic arcs, and a field of stars extending ad infinitum into the receiving black. Our minute part of the galaxy churns restlessly above us and we humans, at bottom complex amalgams of stardust, behold it all as it unfolds.
So, this calendar is admittedly a meager offering. The real experience begins when you venture outside into the night world.
MONDAY, SEPTEMBER 1: MOON 4.1 DEGREES NORTH OF MARS
Oh. why wait? Let's begin the month with a bang. This evening we find Mars and the waxing crescent moon within almost four degrees of each other. Observe them both in the western evening sky. While such Moon-Martian couplings aren't as startling as the Moon-Venusian appulses, they are still quite lovely, particularly as one can enjoy the sky foliage of setting Moon ember and Mars' subtle crimson. If you miss this one, there will be another Moon-Mars event at month's end.
TUESDAY, SEPTEMBER 2: FIRST QUARTER MOON
The first quarter moon rises around noon and sets around midnight. While we tend to associate the moon with nighttime, Luna is as visible during the day as it is after dark. Of course, at night, the moon doesn’t have to compete with the Sun for our attention.
FRIDAY, SEPTEMBER 5: VENUS AT PERIHELION
If you've been following the "Planet Watch" section lately, you'll know that Venus will not be visible until the very end of 2014. It presently lurks far too close to the Sun for our viewing. Of course, it still exists and is progressing through its orbit as inexorably as always. Today, Venus reaches perihelion, the point of least distance from the Sun, about 66.8 million miles. Like all planets, Venus travels along an elliptical, not circular orbit. Consequently, its heliocentric distance (distance from the Sun) veers from a minimum, perihelion, to a maximum, aphelion. Venus' orbit is the least eccentric of all the major planets, meaning that its orbit is the closest to being a perfect circle. Whereas its perihelion distance is approximately 66.8 million miles; its aphelion is 67.7 million and its average is 67.2 million. Perihelion has no effect on its blast furnace climate. However, as it is closer to the Sun than usual, Venus will be traveling slightly faster in its orbit. This event is wholly academic to us, of course, as Venus remains unseen throughout the season.
MONDAY, SEPTEMBER 8: MOON AT PERIGEE
How convenient! We follow a planetary perihelion with a lunar perigee. The similar first syllable is hardly coincidental. "Perigee" is the lunar equivalent of perihelion: the point of least distance from its parent body, Earth. As this perigee occurs less than twenty four hours before the full moon, we'll have another "Super Moon," denoting an unusually large and bright full moon. One will be hard pressed to notice a real difference between a super moon and a regular full moon. However, the high tides will be higher than usual, as the full moon affects the tides more profoundly when at or near perigee.
TUESDAY, SEPTEMBER 9: FULL MOON! (Bronze Event!)
We have yet another "super moon," defined as a moon that is full when it is at or within a day of perigee, its point of least distance. This full moon will be brighter and bigger, but, as mentioned previously, the difference is difficult to observe. An apogee full moon, one that occurs when the moon's distance is greatest, is a beguiling spectacle, as well. Nevertheless, we conferred the bronze medal onto this super moon event, because, being both fun-loving and unprincipled, we don't mind joining the hype.
Also, and, perhaps more importantly, this September's full moon is the famous Harvest Moon, at least by some reckonings. Some define the Harvest Moon as being the full moon closest to the autumnal equinox. This year, the September 9th full moon is slightly closer to the equinox than the October 8th full moon. However, some insist the Harvest Moon is the first full moon AFTER the equinox. By that standard, the October 8th full moon is the Harvest Moon.
SUNDAY, SEPTEMBER 14: MOON 7.4 DEGREES S OF THE PLEIADES
The Pleiades, or Seven Sisters, is the winter's sky forerunner: the object that leads the winter procession across the sky. Tonight, the Pleiades is up by 9:30 p.m. and soon after one will see the Moon rising below it. Being two days shy of last quarter, the moon won't completely obscure the Pleiades. Instead, it will appear as a gibbous next to the Pleiades nebulous light patch.
TUESDAY, SEPTEMBER 16: LAST QUARTER MOON
The last quarter moon rises around midnight and sets around noon. These times are approximations, of course. The last quarter moon occuring around the autumnal equinox tends to be higher in the sky as it is positioned around the highest part of the ecliptic: the Sun's annual path. Watch the last quarter moon rise around 11:21 p.m, nearly forty minutes before midnight.
WEDNESDAY, SEPTEMBER 17: SUN ENTERS VIRGO THE MAIDEN
We often say that the Sun moves through thirteen constellations each year. It does nothing of the sort. Instead, Earth moves around the Sun and it therefore appears to migrate through thirteen constellations. We refer to this retinue as the "Zodiac," or "Ecliptic Band." Today, we see the Sun cross into the Virgo the Maiden region after having left Leo the Lion; The thirteen ecliptic constellations are VIRGO THE MAIDEN; Libra the Scales; Scorpius the Scorpion; Ophiuchus the Serpent Charmer; Sagittarius the Archer; Capricornus the Seagoat; and Aquarius the Water Bearer, Pisces the Fish; Aries the the Ram; Taurus the Bull, Gemini the Twins, and Leo the Lion. The Sun enters Libra the Scales on October 31st.
One interesting note is the duration: the Sun spends more time in Virgo the Maiden than in any other constellation: more than 45 days. The Sun pushes into Virgo during the very end of summer and leaves when the coldest part of autumn begins.
SATURDAY, SEPTEMBER 20: MOON 5.3 DEGREES SSW OF JUPITER
Jupiter has returned to our sky, though it remains quite low in the pre-dawn west. Tonight, one will find the obese planet lumbering next to the crescent moon. Now that Venus is on hiatus, Jupiter reigns supreme as the sky's brightest planet. Observe it next to the night sky's brightest object, the Moon.
SUNDAY, SEPTEMBER 21: MERCURY AT GREATEST EASTERN ELONGATION (26.4 DEGREES FROM THE SUN)
"Elongation" is the angle between the Sun and any other celestial object. For the Moon and all the superior planets -those at a greater distance from the Sun than Earth- the maximum possible elongation angle is 180 degrees: directly opposite the Sun in our sky. The inferior planets, those closer to the Sun than Earth, can only stray so far from Sol. Mercury, the closer of the two inferiors, can't veer more than 28 degrees from the Sun. Venus' maximum is 47 degrees. Tonight, one shall find Mercury in the western evening sky, 26.4 degrees east of the Sun: its greatest elongation during this orbit.
Remember: if a planet is at greatest eastern elongation, it is visible in the western evening sky; if it is at greatest western elongation, it is in the eastern pre-dawn sky.
TUESDAY, SEPTEMBER 23: AUTUMNAL EQUINOX (GOLD EVENT!!!)
Every so often, a seasonal transition is worthy of golden distinction. Granted, there's nothing to see here. However, we're passing from one astronomical season to the next. We have seasons because Earth is tilted on its axis by 23.5 degrees, a value known as the "obliquity." Our summer solstice occurs when Earth's northern hemisphere is aligned toward the Sun as much as possible. When Earth's southern hemisphere is poised toward the Sun, our winter begins. At either equinox, neither pole is aligned toward the Sun more than the other. The autumnal equinox occurs after summer, but before winter.
Interesting note: Earth reaches aphelion -its greatest distance from the Sun- in early July, so our planet is farthest from its parent body in our summer. Consequently, it's traveling at its slowest orbital speed between the summer solstice and autumnal equinox. Therefore, in the northern hemisphere, summer is the longest season.
WEDNESDAY, SEPTEMBER 24: NEW MOON
Beginning of lunation cycle 1135.
Remember, the new moon is not visible. By the weekend, one will see the crescent moon in the western early evening sky.
FRIDAY, SEPTEMBER 26: 4.1 DEGREES NNE OF MERCURY
Sometimes, one can just barely see the crescent moon within a day of the new moon. However, it is best to wait two evenings after new to find the moon. Tonight, the very young waxing crescent moon lingers close to Mercury. Like the razor-thin crescent, Mercury is often difficult to see. Look for both these elusive objects together early this evening.
SUNDAY, SEPTEMBER 28: MOON 1.2 DEGREES NW OF SATURN
The moon veers very close to Saturn tonight in the western evening sky. Within a limited region of the world (parts of the Pacific), the moon will occult, or move in front of, Saturn. Alas, to us, they'll merely look close together.
SUNDAY, SEPTEMBER 28: MARS 3.1 DEGREES N OF ANTARES (Silver event!!)
Why does this event matter? Moreover, why give it a silver medal? The answer is simple: we can see Mars and its rival together in the sky tonight. Antares, the alpha star within Scorpius the Scorpion, is literally named "Rival to Mars," due to its reddish color. Both Mars and Antares appear quite similar: crimson tinctured objects of comparable brightness. (At magnitude 0.8, Mars is the slightly brighter of the two.) Tonight, one has the perfect opportunity to observe Mars and its rival star close together in the western evening sky.
MONDAY, SEPTEMBER 29: MOON 5.6 DEGREES NORTH OF MARS
Mars and the moon make a lovely couple in the western evening sky tonight. Though Mars is not nearly as bright as Jupiter, it is a rather distinctive reddish object when compard to the bright yellowish-white moonlight.
MERCURY (PICK PLANET!!): I am not sure if Mercury has ever been the pick planet before. We'll have to rumage through our archives to find out. September 2014 is a splendid month for Mercury! It is visible all month and at a consistent zero magnitude brightness: about as bright as Vega, the brightest star within the Summer Triangle. In fact, only Jupiter is the only planet brighter than Mercury this month. VERDICT: Seek out Mercury in the western evening sky anytime in September. Best around the time of its eastern elongation. (September 21.)
VENUS: Not visible until late December. VERDICT: Well, there's nothing to see here. Realize, though, that Venus will become quite a brilliant evening sky beacon this coming winter! Those observers yearning to see Venus can take some solace from the assurance that its return will be quite spectacular.
MARS: Mars and Saturn lurk together in the western evening sky. Though equally bright at month's beginning, Saturn's brightness surpasses Mars' by month's end. Mars remains visible throughout the rest of 2014, but its brightness will gradually diminish throughout autumn. VERDICT: Sure, why not look for Mars if you're out in the early evening? It is still brighter than most stars. Mars sets by 9:30 p.m. at month's beginning; 8:30 p.m. at month's end.
JUPITER: Just as Venus promises to be a winter spectacle, Jupiter will also rise to brilliance this coming winter. (We'll enjoy the sight of the two brightest planets looming over a half mile thick sheet of permafrost.) Presently, Jupiter is a pre-dawn sky, rising ever earlier each day. We would have given it the pick planet crown were it not for its early morning apparition. VERDICT: A perfect sight for those observers who rise before the Sun. Look for the bright eastern sky light. If you're partial to early evening eye candy only, you'll have to wait until late autumn/winter for Jupiter to appear during your prime time.
SATURN: We'll lose Saturn in November, but only for a month or so. Now, Saturn and Mars share the evening sky stage. By month's end, Saturn will have the dubious distinction of being the dimmest of the visible planets. Nevertheless, Saturn is still conspicuously bright in the western evening. VERDICT: Find Saturn while ye may, for by October it will be exceedingly difficult; by November, impossible. For those readers who like to plan ahead, Saturn will return to evening sky prominence by next spring.
PLANET ORDER (In terms of decreasing brightness.)
JUPITER - MERCURY - MARS - SATURN