THE SOUTHWORTH PLANETARIUM
70 Falmouth Street      Portland, Maine 04103
(207) 780-4249      usm.maine.edu/planet
43.6667° N    70.2667° W  Altitude:  10 feet below sea level Founded
January 1970
2021-2022: LXIV
"I used to think I was indecisive, but now I'm not so sure."


THE DAILY ASTRONOMER Thursday, January 13, 2022
The Pac-Man Nebula


And there it was poised high above us.
Front and center.
Suitable for framing.
Unutterably resplendent.
Larger than life.

"It is a mistake, ladies and gentlemen, to regard the sky as an inky black
tapestry dotted by stars.   To perceive the sky in this way is akin to
believing that a human being is just bones and ligaments.    The Universe
is exuberantly alive with color.    Our tendency to believe otherwise
attests to our own bodily limitations.  The eye cannot detect color at low
light levels, hence the appearance of non-descript white stars.   We were
able to shuffle off this Earthly coil and embark on an excursion through
the cosmos, we would behold  an array of beguiling nebulae, clusters and
galaxies that would stagger even the most fecund imagination.    Compelling
evidence that our Universe, dismissed by many as a collection of airy
nothings within a soulless vacuum, is in fact the most consummate of
artists, one both driven by an unslakable passion for creation and gifted
with an inexhaustible reservoir of colors.

"And that brings us neatly to the Pac-Man nebula seen above us on the
dome.

[image: 800px-PacMan_Nebula.jpg]

"Instead of scurrying frantically around a ghost-infested labyrinth, this
Pac-man loiters about the Perseus Spiral Arm, about 9,200 light years from
Earth, within the direction of the circumpolar constellation Cassiopeia.
Known as NGC 281 in astronomical accounting departments, this Pac-man is a
gorgeous emission nebula.    These nebulae are so named because they absorb
high energy photons from proximate or embedded stars and re-radiate that
energy along a variety of wavelengths.  The Great Nebula in Orion's sword
is one of the most famous examples."

"Discovered in 1883 by Edward Emerson Barnard, who's the namesake of
Barnard's Star, the one which exhibits the highest proper motion of any
star in our sky, this nebula would disappoint you if you observed it
telescopically.    The vibrant colors are visible only in a time-exposure
photograph.  Such exposures collect a sufficient amount of light so as to
allow the hues to become distinctive.These colors are indicative of the
elements present within the nebula: hydrogen, helium, oxygen and others.  A
beautiful blend of rarefied gasses that will often coalesce to form stars
in the remote future.

"Remember also the grand sizes of these structures. This Pac-Man is nearly
100 light years across.    To give you an idea about that size, one will
find about 1,400 star systems within that amount of space in our part of
the galaxy.  Look up again at the dome above;   the next time you see the
ancient constellation Cassiopeia, recall that it harbors this immense cloud
bristling with energy and color.    Whenever you look at any constellation,
from the Grand Orion to the minuscule Vulpecula, be aware of the artistry
contained within and well outside our view.   From the Witch Head Nebula,
which resembles a laughing crone in profile, to a galaxy shaped like a
cigar and even to Pac-Man, himself.   Tell me the cosmos isn't prodigiously
creative.   Any questions?   Yes, over there."

"Yeah, like, what is Pac-man?"

"I'm not old!"


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