Planetarium

August 2014 Night Sky Calendar

August 2014 Night Sky Calendar
There may be a few who insist that by the time we reach August, our once vivacious summer has attained a sobering maturity.     It has traded its towel over the bare chest look for a cardigan sweater and elbow patches.   Bah!   Summer is as youthful as it ever was.   Unlike humans, seasons are not aware of their advancing age and so behave with reckless abandon up to their demise.  (Hasty note:  Astronomical summer lives on until September 22 10:29 pm EDT, at which time autumn begins and the world implodes in a catastrophe of smoke, horror and misery.  Until that time, rock on!)


Astronomically, August offers an abundance of sky delights: the Perseid meteor shower peak and the Supermoon are two such offerings.  This August, Jupiter returns, Venus vanishes; and Mars draws close to Saturn.


Beyond the solar system's boundaries, the Summer Triangle attains its greatest prominence in the evening sky; the Great Bear (Ursa Major) descends, whilst the Ethiopian Queen (Cassiopeia) rises in the evening..  The Scorpion (Scorpius) sips tea from the pot (Sagittarius) in the South and by mid evening the flying horse (Pegasus) ascends.   Virgo the maiden moves west toward her September departure and in the pre-dawn Orion emerges again.


Join us for a prolonged excursion into the deep summer night.  


FRIDAY, AUGUST 1:  LAMMAS
Though we're posting this calendar a wee bit late this time, we thought that "Lammas" was worth a mention.   Lammas is a cross-quarter day, defined as a day nearly midway between successive seasonal markers, i.e. solstices and equinoxes.    Our calendar contains four such cross quarter days:   Candlemas (Ground Hog's Day) on February 2; Beltane (May Day) on May 1; Lammas on August 1 and Samhain (Halloween) on October 31st.    The CQ day between the summer solstice and autumnal equinox, Lammas is perhaps the most obscure of the four, at least in America.    Meteorologically, Lammas is interesting because it marks our climatological high point.     Were we to average each day's high temperature over the last few centuries, we'd describe an undulating curve throughout the year.   It reaches its low point on February 2nd and its peak on August 1.    Though August can be quite a hot month, the average high temperatures will now decrease until reaching their nadir on February 2nd.   


SUNDAY, AUGUST 3:  MOON 2.2 DEGREES NNE OF MARS
The moon is toward the end of its waxing crescent phase, so it almost looks like a quarter.  Tonight, the moon and Mars are within 2.2 degrees of each other.  Watch them both descend through the western evening sky and set before midnight.     Mars is still conspicuously bright and so the lunar light won't obscure it.


MONDAY, AUGUST 4:  FIRST QUARTER MOON


MONDAY, AUGUST 4:  MOON 0.13 DEGREES WSW OF SATURN (BRONZE EVENT!)
Were we in Oceania, we'd see the Moon occult (move in front of) Saturn.     Since we're not in Oceania, we'll instead see Saturn and the Moon within less than a quarter of a degree of each other.   We've conferred the bronze onto this event because the moon and planet will appear so close together. We understand, of course, that they're not close together, physically; only visually.   


FRIDAY, AUGUST 8:  MERCURY AT SUPERIOR CONJUNCTION
Nothing to see here. The first planet passes on the Sun's far side relative to Earth.   No Mercury viewing tonight!     This event gives us an opportunity to discuss the two conjunction types:  "inferior" and "superior."  "Inferior conjunction" occurs when a planet moves between Earth and the Sun.    Only the inferior planets Mercury and Venus can ever be in inferior conjunction.     Superior conjunction occurs when a planet is on the far side of the Sun relative to Earth.  All the other planets, including Mercury and Venus, can pass into superior solar conjunction.   


SATURDAY, AUGUST 10:  MOON AT PERIGEE/FULL MOON
Yes, ladies and gentlemen, today we have a supermoon!  A "supermoon" occurs when the moon is full around the same time it reaches perigee: its closest distance to Earth.    Though we've promised no repeats this year (and have fulfilled that promise so far), we decided to insert the "Supermoon science" DA posted a few weeks ago:


"Supermoon" is a superb term.   We think it grand and wish it were used more often.     "Supermoon" suggests a far brighter, larger than life moon that one tends to find on science fiction novel covers and, of course, in the movie ET.    The moon garners a great deal of press coverage during these supermoon months, which inspires so many souls to seek it out.     Many of these moon-seekers then ask us, "What is the difference between a supermoon and a moon?"  We then deflate their spirits by replying, "There's not much of a difference at all."

We approach this matter in stages.

First, lunar phases are the result of the Moon's orbital motion around Earth.  Half of the moon is always illuminated by the Sun.    When the moon is between Earth and the Sun, we have "new moon," and none of its area is visible to us.   When the moon is on the other side of Earth, we see all of its illuminated surface, a phase called "full moon."   The changing phases result from the moon's changing position.  The time period between successive full moons, called a 'synodic month,' is about 29.5 days.   The word 'month' derives from this time span, once called a 'moonth.'

Apart from the phase sequence, the moon experiences other cycles.   For instance, the Moon travels around an elliptical orbit, so its distance from Earth changes continually from its closest point, perigee, to its most distant point, apogee.    The time period separating successive perigees, called an "anomalistic month," is approximately 27.6 days.  When the moon is at or near perigee, it appears largest in the sky.   Though its perigee distances, themselves, vary, the moon can appear as much as fourteen percent larger at perigee than it does at its average distance.

Every so often, we'll have the convergence of the synodic and anomalistic months, so that the moon will be full around the time it reaches perigee.  The perigee full moon, otherwise known as the "supermoon," can be as much as thirty percent brighter than a 'regular full moon,' a full moon at its average distance.

In August, we'll have a super moon on the 10th, when the Moon will be full and at perigee!    This moon will be brighter and larger than usual, but, to be honest, the difference will be difficult to observe.  For one thing, we won't be able to observe it next any other full moon.   The landscape will be bright, of course, owing to the lunar light, but it always is when the moon is full.

Although we're behaving like wet blankets on this issue, we still encourage you to venture outside under a full moon and behold a world steeped in the phantasmic lunar glow.   Even when the full moon isn't super, it can still produce a gorgeous nightscape.


SUNDAY, AUGUST 10:  SUN ENTERS LEO THE LION
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 Cancer the Crab region after having left Cancer the Crab  The thirteen "zodiac" constellations are  LEO THE LION; 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 Cancer the Crab.   The Sun moves into Virgo the Maiden on September 17th.  


WEDNESDAY, AUGUST 13: PERSEID METEOR SHOWER PEAKS  (SILVER EVENT!!)
With the possible exception of the Geminids, meteor showers occur when Earth traverses a cometary particle stream: a debris trail left by a comet as it moves through the inner solar system.    The Perseid meteor shower, which began on July 14 and will end August 24, consists of fragments emitted by Comet Swift-Tuttle.   We pass through the densest section this evening, causing the meteor shower to peak.    During this time, we are also experiencing the Delta Aquarid and Alpha Capricornid showers.  However, those showers emit very few meteors.  By contrast, the Perseids are far more numerous and faster, their descent rate often exceeding 59 kilometers per hour.   The Perseids appear to emanate from the constellation Perseus the Warrior, hence the name.   Best times to observe the shower are after midnight, when our part of Earth moves into the meteoroid stream.


Unfortunately, the gibbous moon's light will interfere with our observations, making the Perseids more difficult to see.  Generally, one can expect to see 15 - 30 meteors an hour around midnight.  The moon will reduce that number.  In fact, were it not for the lunar light obscuration, we might have awarded this event the gold medal.


SUNDAY, AUGUST 17:  LAST QUARTER MOON


MONDAY, AUGUST 18:   VENUS 0.21 DEGREES NORTH OF JUPITER (GOLD EVENT!!!)
We're losing Venus and regaining Jupiter.   This morning, we'll see the descending goddess close to the rising god king.  Venus, as always, is the more brilliant of  the two worlds.   At magnitude -3.9, Venus will be nearly seven times brighter than -1.8.   This appulse represents the closest planet-planet conjunction of 2014.    It is partially for this reason that we've given this one the gold!    


SATURDAY, AUGUST 23: MOON 5.3 DEGREES SSW OF JUPITER
Provided one ventures outside early, one can see the waning crescent moon close to Jupiter.   The mammoth planet climbs slightly higher in the pre-dawn sky every morning and is also brighter than any night sky star.    A beautiful coupling, though not conveniently timed.


MONDAY, AUGUST 25:  NEW MOON
Beginning of lunation 1134.


MONDAY, AUGUST 25:  MARS 3.4 DEGREES SSW OF SATURN
Think of it this way:  the Jupiter-Venus appulse was the original movie; the dimmer Mars-Saturn gathering is the less impressive sequel.   They're both equally bright, though ten times dimmer than Jupiter and  almost seventy times dimmer than Venus. Distinguishing between them will be easy, however, as Mars is distinctly reddish.  Find Mars and Saturn over in the western evening sky tonight.       


WEDNESDAY, AUGUST 27:  MOON 3.2 DEGREES SSW OF MERCURY
The thin, waxing crescent moon and Mercury are well over in the western evening sky. As they're about 17 degrees from the Sun, both worlds will be low by the time Mercury becomes visible.    You can try to find them both, but we wish you luck.


FRIDAY, AUGUST 29:  NEPTUNE AT OPPOSITION
We generally focus on five planets: Mercury, Venus, Mars, Jupiter and Saturn.  We tend to neglect the others because they're not visible unless viewed through a telescope.  However, we thought we'd mention that Neptune is at opposition, meaning that it is on the far side of Earth relative to the Sun. Superior planets are generally brightest around opposition because they're also closest.  Neptune is at maximum brightness, but it still more than six times dimmer than the dimmest naked eye star.,


SUNDAY, AUGUST 31:  MOON 0.96 DEGREES EAST OF SATURN
One might wonder:  why was the first Moon-Saturn event a bronze winner, but this one is sans medal?  Simple:  the previous Moon-Saturn encounter was closer and therefore more noteworthy.  See the waxing crescent moon and Saturn together in the early and mid evening sky,




PLANET WATCH


MERCURY:  The first world isn't visible most of August.   It peeks up in the early evening by late month, but even then will be exceedingly difficult to observe.   VERDICT:  You know, Mercury will be visible throughout all of September, so don't go out of your way to find Mercury this month.      If you must, wait until the last few days and look into the early evening western sky.


VENUS:  Well, we've been warning you for awhile.  Venus leaves this month and won't return until late December, when it emerges into the early evening sky.     Venus will be absent all autumn.  This month, it descends toward the Sun in the pre-dawn.    VERDICT:   This fall will try your soul if you're a Venus admirer.    Take this opportunity to glimpse it before its prolonged hiatus.   One note of consolation:   Venus will return to become a brilliant winter sky object.


MARS: (PICK PLANET!)    We had a difficult time choosing this month's pick planet.   Mercury isn't prominent, Venus is a pre dawn object; Jupiter has just returned.  That left us with Mars and Saturn.  We opted for the latter because it is slightly brighter: magnitude 0.6 as opposed to Saturn's 0.7.  (Recall that the brighter the celestial object, the lower the magnitude number.)  Mars is a beautiful, moderately bright fire opal planet in the western evening sky.    VERDICT: Easy to find if you're out a few hours after darkness descends.     Seek out of the western sky's red eye.


JUPITER:  Jupiter left in July and has now returned.   This king planet is a pre-dawn object all month, but will rise earlier each day.   Though dimmer than its companion, Venus, Jupiter still outshines the other planets and all the night sky stars.  VERDICT:   A lovely sight for early risers, Jupiter grows brighter throughout the remainder of 2014.  So, if you miss it now, you'll have ample opportunity to observe it later.


SATURN:  Saturn shares the evening stage with Mars and is almost as bright.  Whereas Mars remains visible throughout the year, Saturn leaves in late October and returns early December.   VERDICT:   If you're looking for Mars, might as well search for Saturn.  The two planets will be closest to each other on August 25th.  


PLANET BRIGHTNESS (from brightest to dimmest)


VENUS - JUPITER - MERCURY-MARS-SATURN
(When Mercury appears late month, it will be brighter than Mars and Saturn already.)

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