Star clusters and
galaxies will keep you
looking at Hercules
all night long.
BY MICHAEL E. BAKICH
THE CONSTELLATION
HERCULES(pronounced HER-cue-
leez) is one of the original star figures
created by the Greeks, who called the
hero Herakles. The main part of the pat-
tern is reasonably easy to find. It’s visible
from mid-spring through mid-fall in the
Northern Hemisphere. Its center lies at
R.A. 17h21m and Dec. 27°30'.
Hercules ranks fifth in size out of the
88 constellations, covering 1,225.15
square degrees (2.97 percent) of the sky.
And while its size places it near the top
of that category, it fares worse (48th) in
terms of overall brightness.
The best date to see Hercules is
June 13, when it stands opposite the Sun
in the sky and reaches its highest point
at local midnight. The constellation is
completely visible from latitudes north
of 39° south and totally invisible only
south of latitude 86° south.
Although this star pattern isn’t
bright, it contains two Messier objects,
both globular clusters: M13 and M92.
You’ll find lots of other worthy targets,
too. Let your telescope adjust to the
outside temperature, get comfortable,
and spend an enjoyable night leisurely
making your way through the many
great deep-sky objects residing in
Hercules. Good luck!50°40°30°20°10°19h 18h 17h 16hNGC 6229M92NGC(^6207) M13
NGC 6210
95
Abell
2151
Vega
MAP SYMBOLS
Globular cluster
Planetary nebula
Galaxy
DRACO
LY R A
OPHIUCHUS
HERCULES
CORONA
BOREALIS
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Rasalgethi
The Hercules Galaxy Cluster (Abell 2151) lies at the
astounding distance of 500 million light-years from
Earth. Abell 2151 requires at least a 12-inch telescope
and eyepieces that give powers in excess of 250x.
Target its brightest member, the elliptical galaxy
NGC 6041, which glows at magnitude 13.4.
KEN CRAWFORD
The Hercules Cluster (M13) is the standout deep-sky
treat in this constellation. It glows at magnitude 5.8
and has a diameter of 24'. Under a dark sky, you’ll
spot it with your naked eyes two-thirds of the way
from Zeta (ζ) to Eta (η) Herculis. Through 8-inch
and larger scopes, you’ll see hundreds of stars.
ADAM BLOCK/MOUNT LEMMON SKYCENTER/UNIVERSITY OF ARIZONA
52 ASTRONOMY • JUNE 2022
AS
TR
ON
OM
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RO
EN
K
EL
LY
Michael E. Bakich is a contributing editor
of Astronomy who enjoys slowly moving his
telescope through a single constellation.