My first Magazine Sky & Telescope - 04.2019 | Page 45

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Coma
Star Cluster
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5° bino
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cula
COMA BERENICES
vie
M64
Binocular Highlight by Mathew Wedel
Best and Brightest
I
WHEN TO
USE THE MAP
Late Feb
Early Mar
Late Mar
Early Apr
Late Apr
Midnight
11 p.m.
11 p.m.*
10 p.m.*
Nightfall
*Daylight-saving time
f you look east in the early evening this time of
year, you should fi nd the constellation Coma
Berenices, or Berenice’s Hair, which honors Egyptian
queen Berenice’s sacrifi ce of her hair to the gods.
The queen’s legendary gift lies about 2° south
of Gamma (γ) Comae Berenices, in the form of the
Coma Star Cluster, the glittering jewel of the constel-
lation for naked-eye and binocular observers. I’m not
going to describe it here — I have homework for you
instead. Right now, we’re in the narrow springtime
window in which we can catch the closest, brightest,
and best star clusters in the sky at the same time in
the early evening. The Coma Star Cluster is rising in
the east as the Pleiades, Hyades, and Alpha Persei
Cluster are all sinking toward the western horizon.
This affords us the opportunity to easily compare
these celestial wonders.
Closest to us at 150 light-years is the Hyades, in
Taurus, the Bull. Next comes the Coma Star Cluster,
at about 280 light-years, then the Pleiades at 440
light-years. The most distant of the four clusters is the
Alpha Persei Cluster, which lies 600 light-years away.
The Alpha Persei Cluster occupies so much sky com-
pared to the others because it’s actually immense,
more than 30 light-years across. In contrast, the
Coma Star Cluster is about 20 light-years across, and
the Hyades and Pleiades around 15.
I urge you to spend some time comparing and
contrasting these clusters with your binoculars and
with your naked eyes. Whether doing so inspires you
to contemplate cosmic time and distance, or simply
to enjoy some of the fi nest sights in the night sky, it
will be time well spent.
¢ MATT WEDEL is fi nding it a challenge to stuff
even a small star cluster into his brain. Binoculars
certainly help.
sk yandtele scope.com • A PR I L 2 019
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