Last year this time, I was sitting on my in-laws’ couch trying to figure out how I was going to bring Flying Squirrel Outdoors to life.  Though I officially didn’t kick it off til Jan 1, it’s hard not to think about where I’ve been this past year, ups and downs…  And interestingly enough, part of what brings it home is the realization that I’ve been watching the sky regularly, every week for a year – and things are back where they started.

First off, some unique, “transient” events this week – meaning things that will happen briefly this week and then be gone…

Planets Dawn 171230

Looking SE about an hour before dawn, Dec 30, 2017.  via Stellarium

Mercury, Jupiter and Mars — For the past couple months, there’s been a pre-dawn dance going on between the planets.  Venus and Saturn have hidden in the glare of the Sun, while Jupiter and Mars are running away, higher, to the west.  By the end of this week, Jupiter and Mars will be cozying up together.  Before dawn, look for the dim red dot of Mars just to the right of bright Jupiter – they’ll be in close alignment by January 6, so stay tuned…  Down closer to the horizon, look for surprisingly-bright Mercury to rise about an hour before the Sun.  It ought to be visible, even as the horizon starts to glow, a couple finger-widths to the left (north) of bright red Antares, the star in the neck of Scorpius.  Mercury is nearing its maximum elongation from the Sun, so its relative speed is fairly slow this week, hovering in about the same position night after night, even as Jupiter and Mars converge.

 

Aldebaran and the Moon — We’ve had a few of these this year.  The Moon will occult Aldebaran next Saturday evening, Dec. 30.  The event is visible for almost the entire US and Canada early in the evening, and northern Europe later.  Check out the timetables here for specific information on your location.

Now, for a more general tour of the sky these days, (and I hope you don’t mind my re-using some recent pics to show the way!)

 

Cygnus Winter

The cross of Cygnus standing in the west, just after dark on Christmas Eve.  Brightness is hard to capture in a 2-D image, but squint a little and the cross will pop out!

First, after the Sun has set, face west.  The first thing you may notice – and to some this pretty appropriate here on Christmas Eve – is the shape of a very-well-proportioned cross, standing upright on the western horizon, with its brightest star at the top.  This star is Deneb, and the cross is the constellation Cygnus, the Swan.  It represents a swan in flight, with its head stretched out down low, the crossbar its wings, and Deneb its tail.  Not religious at all, but still, the orientation of the cross this week is pretty neat.

 

Down to the lower left of Cygnus, you’ll see bright Altair on the horizon (in the constellation Aquila).  To the lower right, you’ll see bright Vega (in Lyra), also on the horizon.  These three stars make the “Summer Triangle” asterism, and as you can see – that constellation is departing the sky to make room for winter stars.

Now, pan right, to the north.  You may not even see it – but the Big Dipper asterism in Ursa Major is lying low on the horizon.  The great bear is hibernating for the winter, and will rise again soon.

Back to Cygnus, look up and left – you’ll see the Great Square of Pegasus.  And above and to its right (almost straight up), the now-sideways “W” of Cassiopeia.  Between the two, if the sky is dark enough, you might see the Andromeda Galaxy, our nearest “regular galaxy” neighbor (not counting the Magellanic Clouds in the southern hemisphere).  Appearing as a faint smudge to the naked eye under dark skies, Andromeda pops in a small telescope or with binoculars.  The Milky Way is not its brightest in this area, but under really dark skies you might see the ribbon of stars extending from Cygnus up through Cassiopeia.

Andromeda

The Andromeda Galaxy, captured via long-exposure DSLR.

Keep on tracing this west-east arc (you can turn around now), through Cassiopeia, and through Perseus (full of nice clusters, and looking to me like 2 arcs placed back to back, like one bowl stacked on another placed upside down on the counter), to Auriga, the Charioteer.  Auriga is a rough pentagon, with bright Capella at one of its points, high in the sky.

Plieades

The Pleiades

To the right (south) of Auriga, you’ll find two of the most apparent naked-eye clusters in the sky — the Pleiades (or Seven Sisters) is a tight test of clarity and vision, and the “V-shaped” Hyades below it, making up the face of Taurus the Bull, with bright Aldebaran at the lower tip.

Below the Hyades is possibly the most famous, and certainly the brightest, winter constellation, Orion, the Hunter.  Orion is lying almost on his back, his belt of three stars vertical.  Betelgeuse is the bright red giant in his left (from our perspective) shoulder, and blue-white Rigel is is right knee.  Note the Great Orion Nebula in the Hunter’s sword – the middle star is not a star at all…

Hyades

The Hyades, and Aldebaran

To the left (east) of Orion, the Gemini twins are lying down, with Castor and Pollux forming a short vertical line and marking the twins’ heads.  Their feet point back toward Orion.  Squint and you can see a pretty clear image of stick figures holding hands.

Finally, look beneath Gemini to find the bright star Procyon, in otherwise unremarkable Canis Minor, the Small Dog.  At about the same elevation, a couple fist-widths to the right (south), you’ll find Sirius, in Canis Major, the Large Dog, at Orion’s heels.  This “Dog Star” is the brightest in our sky.

Orion

Orion rising.  The three near-vertical stars are his belt, and his sword, including the Great Orion Nebula, is just right of center at bottom.  Taken with a long-exposure DSLR, no telescope.

Sirius, Procyon, and Betelgeuse form a large equilateral triangle — the “Winter Triangle” coming into the night sky to join us for the next few months.

 

Hopefully you enjoyed this brief tour, and could follow along.  Learning the relative positions of the constellations like this, and learning to leapfrog from one to another, is really helpful for navigation, timing, and just keeping track.  We may not NEED this knowledge these days, but if you spend any time outside at night, it sure does help!

Get Out There!
Troy
http://www.flying-squirrel.org

6 thoughts on “Winter Sky (Astronomy: Week of 12/24/17)

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