Tonight’s Sky December – Constellations
December Night Sky. The long, frosty nights of December make for good sky gazing when the stars shine clear and bright.
Face north to find the Big Dipper scraping the northern horizon.
The constellation of Cassiopeia the queen swings high on the other side of Polaris, the North Star.
The queen’s star pattern forms a clear “W” or “M” shape in the sky.
Snuggled in the M pattern is Eta Cassiopeiae, a binary with a pale yellow Sun-sized star and a less
massive orange companion.
Also tucked within the M pattern is the open star cluster M103.
Binoculars or a small telescope show a fan-shaped group of about 170 stars, with a red giant star near
To the east of Cassiopeia lies the fainter constellation of Cepheus, the king.
His dim shape looks like the outline of a house.
Along the base of the house lies Mu Cephei, a red giant also known as the Garnet Star for its deep red
It’s also a variable star, changing in brightness over hundreds to thousands of days.
To one side of the house’s base sits NGC 6946, a ragged spiral galaxy that appears as a ghostly patch of
light in modest telescopes.
NGC 6946 is known as the Fireworks Galaxy because of the frequency of supernovas occurring within it:
10 within the past century. By comparison, the larger Milky Way averages just two per century.
X-ray emissions, shown in purple, reveal a galaxy filled with remnants of supernovas, whose energy
contributes to heating surrounding gas.
To the west of Cassiopeia we find the sprawling pattern of Perseus, the Greek hero and slayer of
Medusa, whose head he carries.
Among Perseus’ stars lies the open star cluster M34.
Small telescopes or binoculars show a concentrated scatter of about 100 stars.
Face north to locate the Big Dipper and find galaxy M82.
In binoculars and small telescopes, the galaxy appears as a thin rod of light.
M82, seen edge-on, experienced a tremendous burst of star formation after an encounter with another
This multi-wavelength image shows the effects of this starburst as it blows out dust, shown in red, and
hot gas, shown in blue, from its central regions.
Face east to find Orion the hunter with his shining belt rising over the early winter landscape.
The glittering stars of winter rise with Orion and promise many fine stargazing nights to come.
Celestial wonders await you in tonight’s sky. December Night Sky.