Summer’s swan song can be heard. It is a soft song. A familiar melody, beautiful and yet
melancholy. The Milky Way, the celestial river of life, the “place of spirits”, the connection
between Earth and sky, presently flows in a different direction. Outside your window the
Milky Way runs almost directly north to south, dividing the night sky into east and west.
The constellation Cygnus, the swan, nowadays majestically glides above our galactic river
heading south, sings a song of grand farewell. What do you hear? A change of season is
Afoot.
A new season of harvest, fulfillment, and gratitude awaits. Straddling the season of
growth with the season of harvest, the September night sky is rich, full of delight, and
magical objects to view and events to observe. Here are just a few of the September
stargazing highlights.
The Autumnal Equinox: September 23st
In the northern hemisphere, the autumnal equinox occurs on September 23rd, at 12:50am
MT. The date of the autumnal equinox demarcates the end of the summer season and the beginning of the autumn season. On this day, the center of the Sun sits high over the equator, and spends roughly equal amounts of time above and below the horizon at every
location on the Earth. No matter where you are in the world, the sun rises due east, and sets due west. Stand anywhere on the equator at noon and look straight up, the sun is directly overhead. There are two equinox a year, one in autumn, and one in spring which are opposite of one another. More so, every planet in our solar system has an equinox when its tilt and orbit result in both hemispheres receiving equal amounts of light.
In Japan, Autumnal Equinox Day is a public holiday. It is a day when individuals take time
to reconnect with their families and by tradition tend to the graves of ancestors, visit
shrines, and meditate in temples.
Jupiter in Retrograde: September 4th
The chief deity among the pantheon of gods in Roman mythology, as well as the Roman
state religion, is Jupiter. The presence of the god of the sky and thunder, The Sky Father,
currently in the night sky is overwhelming. Follow it through the southern sky at night,
and Jupiter beams, radiates, and illuminates befitting a god. Maybe it’s because we haven’t seen our fifth planet, the largest planet in our solar system, in the night for some time that it appears so big and bright? Or, seeing it now, at first sight, it appears to be an aircraft’s landing lights. But the light stands still. Or, is it moving backwards? What's happening? This September 4th, Jupiter begins its retrograde period.
What does it mean when a planet goes into an apparent retrograde? First, it is a trick of
the eye due to our view of the solar system from Earth. The inner planets of our solar
system orbit the Sun “faster” than our outer planets do. Since all of the planets travel in
the same orbital direction around the Sun, and with the Earth closer to the Sun than
Jupiter, its orbit will have it to catch up to and then overtake Jupiter, as it travels its own
orbit. For us looking out at Jupiter, this inside out view creates the illusion that Jupiter
stops in the night sky, and then moves backwards, and then zig-zags. When have you
experienced an apparent retrograde? Think of time driving a car when you pass another
car moving in the same direction on a highway. As your car gets close to, next to, and
then moves past it, the other car appears to slow down. Kind of weird, eh? With Jupiter commanding our full attention this month, take a moment to glance at it over a few nights in a row and see if you notice its zig-zagging in the sky.
The Andromeda Galaxy: The entire month of September
The arrival of autumn brings with it many of the night sky’s most spectacular
constellations and grand mythological stories. One of the easiest to find after sunset is
the constellation Cassiopeia, the vain Queen, and mother of Andromeda. Look to the northeast horizon edge after 8:30pm MT for five bright stars all of similar brightness (magnitude) that together create an asterism, the shape of a somewhat flattened letter “W.” The brightest star of the “W 5” is called Schedar. It will be our pointer star to find the Andromeda Galaxy. (Just to confuse things more, there is a constellation named Andromeda, as well as a galaxy named Andromeda.) The Andromeda Galaxy is a barred spiral galaxy just like our Milky Way and is the nearest galaxy to us. It has spectacular broad sweeping arms, one extending from each end of its bar. As it resides an intimate 2.5 million light-years from Earth, we can see it with our unaided, naked-eyes.
First, get familiar with the above image and as it points out the location of the Cassiopeia
Galaxy. Second, get to a dark location with as little light pollution as possible. To find the
constellation Cassiopeia locate the five bright stars forming the “W” above the northeastern horizon. Then find Schedar, the brightest star of the five. You’ll notice it is at the bottom of the “W” creating a funnel-like pointer from which you draw an imaginary straight line back to the horizon. To find the galaxy, extend your arm out and make a fist. Place the thumb of the closed fist on the star, Schedar. Maintain the angle set by the pointer star, and turn your wrist on the imaginary straight line down towards the horizon. When the line hits the horizon, at the other end of your fist, the pinky finger, then look for a faint, slightly brighter patch of diffuse light. Look for a light fuzzy white finger print of chalk on a window pane about the size of dime. That patch is the Andromeda Galaxy.
Give your eyes time to adjust and as they do, the galaxy’s fuzzy size will increase and
become more apparent. It will look like a large oval serving platter. It’d be appropriate to
say “Whoa!” when you see it.
The Constellation Pegasus: The Great Square of a Winged Horse
While you’re in the neighborhood, take a step to the right of the Andromeda Galaxy and
locate another asterism, the Great Square of Pegasus. It’s easy to find notwithstanding the
stars in the square are a bit dimmer. The brightest star of the great square is Alpheratz.
This star occupies the upper left corner of the square. To find it, start at the Andromeda
Galaxy, and move one fist width towards the south maintaining the same eastern latitude.
Each side of the square is approximately two fist width in length. You are looking at the
midsection of a half horse. The upper right corner of the square are the front legs; and
the stars in the lower right corner of the square represent the horse’s neck and head. (The
two lines of mid-bright stars connecting to Alpheratz, is the constellation Andromeda.) The
challenge in seeing Pegasus is that it flies upside down through the night sky! You’ll need
to be a little creative.
Little Mercury Rises Tall and Bright, September 24th
Sad to say, Mercury doesn’t get as much attention. Maybe this is because the Message of
the Gods is constantly on the move and hard to pin down? Fair to say, the planet Mercury
certainly has a type A personality. What about having little Mercury join you for an early
morning cup of coffee on the 24th? Sounds like a great way to start your day.
As an inferior planet, we only get to view Mercury either at dusk or sunrise and then only
for brief periods. Unfortunately, with Mercury’s orbiting so close to the Sun, it spends most
of its time in the Sun’s glare. Fortunately, this September brings Mercury’s best viewing as
it brightens rapidly rising higher in the sky with each passing morning.
Let’s do this right. Get your coffee and then look east to greet the new day. Around
6:30am MT, the brightest object in the sky is the planet Venus. From Venus, draw an
imaginary line straight down to where the Sun is about to break over the horizon.
Point your outstretched arm towards the horizon and make a fist. Place your thumb on the
edge of the eastern horizon, and rotate your fist up so your pinky lines up with Venus
across the top of your knuckles to your thumb, and finally the horizon. Mercury will be about a fist and a half up on this imaginary line between the horizon and Venus. At 17 degrees above the horizon you’ll see a bright pinprick of light. That’s Mercury. Oh, and be quick about it; Mercury has messages to deliver.
Each new season calls us forward, as well as asks us to be grateful for that which has
passed. The summer celestial season has given much to us to see, enjoy, and contemplate. We feasted on the undeniable beauty and brilliance of Venus’ radiance high in the western sky. We “ooh and aah” at the unexpected sighting of a meteor streaking across the heavens. We stared dumbfounded at the brighter fuzzy patch of light at the southern end of the Milky Way after we learned we’re looking at the galactic center of our Milky Way galaxy. We gazed up at the Summer Triangle of constellations, our constant companion through all of summer.
It is appropriate that we take a moment to pause and watch Cygnus lightly fly south through our river of stars. Equally fitting it is that we turn towards the season of autumn. With anticipation and excitement let’s look up together to a new night sky full of celestial joy and wonder just waiting for us to harvest.
Clear skies to you!
