Sky & Telescope - April 2024 - 43

ε
URSA MAJOR
ζ
Mizar
M101
BOÖTES
θ
κ
Alkaid
η
M51
b
λ
i
χ
Binocular Highlight by Mathew Wedel
n
M63
Whirlpool Time Machine
O
ur target this month is Messier 51, the Whirlpool
Galaxy. M51 lies in the constellation Canes
Zenith
Venatici, the Hunting Dogs, but it's in the far northeastern
corner - it's closer to the Big Dipper asterism in
Ursa Major, the Great Bear. Trace the last line of the
Dipper's handle, from 2.2-magnitude Mizar, or Zeta
(ζ) Ursae Majoris, to 1.9-magnitude Alkaid, or Eta (η)
Ursae Majoris. Then hang a left and scan 3° southwest
to find a neat little triangle of 7th-magnitude stars, like
a pyramid pointing back to Alkaid. M51 lies just past
the base of the pyramid.
You've seen M51, of course. The Whirlpool is a
ζ
0°
ε
α
perennial favorite of amateur and professional astronomers
alike. And you'll see it again in binoculars - at
magnitude 8.4, it's an easy catch under reasonably
dark, clear skies. But in anything smaller than giant,
mounted binoculars you won't see any detail, possibly
just an oblong, fuzzy glow. The trick to observing galaxies
with binoculars is to look not just with your eyes,
but with your mind.
M51 lies about 30 million light-years away. The light
-20°
we see now started its journey when our ancestors, the
Old World monkeys, were only recently separated from
the New World monkeys. Presumably that separation
happened when the latter were swept out to sea on
natural rafts of vegetation, to cross an Atlantic Ocean
that was then only half as wide as it is today.
What a delight, to get so much from a tiny ball of
WHEN TO
0h
g Sou
USE THE MAP
Late Feb Midnight
Early Mar 11 p.m.
Late Mar
11 p.m.*
Early Apr 10 p.m.*
Late Apr Nightfall
*Daylight-saving time
fuzz glimpsed through binoculars. That heady perspective
- measuring our own history against the cosmos,
with nothing more than a little bit of steel and glass -
crystallizes a lot of my motivation to stargaze. After all,
I'm just another curious primate looking up at night.
¢ MATT WEDEL thinks that binoculars make pretty
good time machines - with no risk of getting munched
by dinosaurs.
sk yand tele scope .o r g * APRIL 2024 43
CANES VENATICI
5
c
CANIS
MINOR
γ
P Y X I S
α
β
π
ζ
°
o
A T O R
u
β
l
a
M44
C A N C E R
α
M67
Moon
Apr 15
r
Sickle
Mars
Regulus
v
P U P P I S
α
i
M46
M47
M93
ε
δ
γ
Venus
e
β
α
Moon
Apr 12
w
Sirius
M41
β
Fac
L Y N X
1h
M48
M O N O C E R O S
α
4h
C A N I S
M A J O R
κ
α
µ
ing
E Q U
Alphard
I A
7h
V E L A
th
M81
M82
+80°
+80°
C E P H
δ
ε
22
gnic
ζ
+60°
M50
δ
η
L E P U S
S
W
α
Betelgeuse
O R I O N
δ
ε
M42
β
Rigel
λ
Bellatrix
E R I D A N U S
A U R I G A
M37
α
ε
Capella
P E R S E U S
Algol
M34
caF
GEM I N I
α
Procyon
ζ
κ
Aldebaran
T A U R U S
CAMELOPARDALIS
M52
CAS S I OP E I A
Double
Cluster
A N D R O M E D A
Polaris
α
ε
δ
γ
β
M35
ζ
W
e
M36
M38
ε
ζ
β
ρ
δ
α
γ
gni
Pollux
α
Castor
cin
g
α
Pleiades
α
ε
θ
Hyades
ι
ο
χ2
χ1
γ
β
δ
θ
β
γ
β
st
β
δ
ε
ξ
µ
η
F
a
ι
γ
γ
α
W
N
a F
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Sky & Telescope - April 2024

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