THE SOUTHWORTH PLANETARIUM
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Founded January 1970
Julian Date: 2458863.16
2019-2020:  LXXXIV
                  "Such as are your habitual thoughts, such also will be
the character of your mind; for the soul is dyed by the thoughts."
-Marcus Aurelius


THE DAILY ASTRONOMER
Tuesday, January 14, 2020
Winter Triangle Rising

[image: wintert.jpg]

Unless you've been cloistered in a stardome for the last few weeks
enshrouded in eiderdown comforters and surrounded by space heaters while
obstainely refusing to interact with other humans, you will know that
winter has arrived in earnest.     Alternating layers of ice and snow coat
our iron-hard Earth and a deep chill settles onto the world during each
interminable night.      Oh, blah!   What a miserable attitude!

Hey, despite the hiemal gloom and widespread dormancy of flora and fauna,
the sky remains a veritable festival of brilliant stars. In many ways, the
winter sky is the most wonderful of them all:   not only is the boundless
sky ablaze with beguiling lights, the sun still sets early enough to afford
everyone a view onto the cosmos the Sun cleverly obscures every day.  Also,
the reduced radiational cooling in early evening reduces the atmospheric
obscuration: the air is calmer and the view less obscured by the thermal
turbulence that ripples through the unquiet summer night sky.     Moreover,
there is the Winter Triangle.  Formed by Sirius (the brightest star),
Betelgeuse and Procyon, this triangle is smaller than its Summer
counterpart, but brighter. It is the easier of the two patterns to observe.


Now that thee Summer Triangle has largely vanished into the dusk, the
Winter Triangle is ascending into the eastern evening sky.    January is
the famous (well, somewhat well known) Triangle transition month, marking
real winter's onset.      Today, we welcome the Winter Triangle's return to
prominence.

The three stars are each part of a different constellation.    Sirius
represents the collar of Canis Major, the larger of Orion's two hunting
dogs.    Procyon is the brighter of the two stars the form Canis Minor, the
smaller dog.   Betelgeuse is Orion's eastern shoulder star, or in cultures
frightened by (and therefore obsessed with) nakedness, Betelgeuse is the
clasp on Orion's tunic.

Mythologically, the formidable hunter Orion maintains a stubborn pursuit of
the elusive Seven Sisters, or Pleiades.   His dogs dutifully follow,
despite their greater distance from and, let's face it, far reduced carnal
interest in, Atlas' seven daughters.      Of course, the constellation
stories vary considerably, as we can see in the image above that depicts
Orion as facing the other direction.

Astronomically, the stars comprising the Winter Triangle seem quite close
together. They are nothing of the sort.   Sirius is merely 8.4 light years
away, almost at an arm's length.    Procyon is slightly farther away at a
distance of 11.5 light years.    Betelgeuse occupies a far deeper part of
the pool at a distance of 620 light years.      Whereas we're seeing Sirius
as it was in the summer of 2011, and Procyon in the summer of 2008, we're
seeing Betelgeuse as it appeared in the early 15th century!

Despite its name,  Winter Triangle will remain in our evening sky until
May, when it will begin the night low in the western sky.   Sirius, being
the southernmost star, will vanish first  by  early May, followed by
Betelgeuse in mid May and Procyon by the end of May.   Naturally, they will
all return to the early morning sky by early September:  a cycle that has
continued for centuries and will persist for centuries more.


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