Sky & Telescope - July 2022 - 43

σ
φ
Galactic
Center
M54
SAGITTARIUS
M70
M69
δ
γ
SCORPIUS
M6
45
OPHIUCHUS
ε
M7
η
CORONA
AUSTRALIS
λ
G
κ
Binocular Highlight by Mathew Wedel
A Tail of Two Clusters
O
η
M13
ES
ζ
υ
ur targets this month are the open clusters
M6 and M7 in the tail region of the constellation
Scorpius, the Scorpion. M6 is also called the
Butterfly Cluster owing to its appearance, while M7 is
known as Ptolemy's Cluster after Claudius Ptolemy,
who first recorded it around AD 130.
To find the two objects, scan just north of the
β
M12
C H U S
ν
σ
α
M4
τ
ε
µ
ζ
7h
g Sou
WHEN TO
USE THE MAP
Late May 2 a.m.*
Early June 1 a.m.*
Late June Midnight*
Early July 11 p.m.*
Late July Dusk
*Daylight-saving time
π
β
δ
brightest star in the Scorpion's tail - magnitude-1.6
Lambda (λ) Scorpii - or west from Gamma (γ) and
Epsilon (ε) Sagittarii in the spout of the Sagittarius
Teapot. (Turn to page 20 to read about globular
clusters in this region of the sky.) I like to imagine
the bright stars of the Teapot and the tail of
Scorpius as hands supporting a cat's cradle, with
M7 firmly ensnared and M6 having made a narrow
escape to the northwest. M7 is the bigger and
brighter of the two clusters, but both are dead-easy
in binoculars and are even naked-eye visible under
good conditions.
As viewed from Earth, M6 and M7 lie pretty close
to the galactic center, but that's a sort of visual pun.
The two clusters are actually much closer to us, only
about 1,500 and 1,000 light-years away, respectively.
By contrast, the Lagoon Nebula (M8) and Trifid
Nebula (M20), which also appear nearby in the sky,
are much farther, more than 4,000 light-years distant.
And the galactic center is another 23,000 light-years
farther still. So, observing this stretch of the Milky
Way gives us practice appreciating that space is, well,
space: It has depth. If you plumb those depths with
your binoculars, you'll have a better appreciation for
the scale of the galaxy and our place in it, and I think
that's a pretty good way to spend a summer evening.
¢ MATT WEDEL tries to really feel the three-dimensionality
of the night sky when he looks out - not
up - into it.
sk yand tele scope .o r g * JULY 2022 43
5
E
°
Q U A T
b
β
γ
α
σ
i
n
E
L I B R A
C
L
o
I
P
T
β
α
c
I
C
C E N T A U R U S
S E R P E N S
( C A P U T )
M5
u
Moon
July 6
Fac
11h
l
a
ing
ε
δ
β
η
α
r
S
W
Spica
v
γ
δ
i
C O R V U S
e
CORONA
BOREALIS
Moon
July 3
w
M51
α
CANES
VENATICI
β
8h
κ
δ
ε
ζ
oon
ly 10
Antares
14h
O R P I U S
th
O R
χ
η
γ
ϕ
L U P U S
δ
D R A C O
Thuban
γ
CAMELOP
5h
gnic
V I R G O
B O Ö T E S
Arcturus
M3
COMA
BEREN I CE S
W
e
β
δ
θ
L E O
γ
β
L EO
M I NOR
L Y N X
η
α
L i t t l e
D i p p e r
β
U R S A
M I N O R
aF
η
Mizar
& Alcor
B i g
D i p p e r
U R S A
M A J O R
M81
M82
π
γ
α
α
β
α
cin
g
ε
st
µ
β
γ
η
F
a
β
gni
α
ξ
ν
ψ
µ
λ
ο
θ
κ
α
ι
ζ
ε
γ
δ
W
N
caF
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