While most planetary nebulae are small and beautiful, there is no doubt that the Dumbbell Nebula
(M27) is something special. Found by Charles Messier in July 1764, M27 was the first planetary
nebula ever discovered. He described it as a “nebula without star ... oval in shape.”
Decades later, John Herschel remarked it resembled “a nebula shaped like a dumbbell,” a
nickname that stuck. He also subsequently coined a second nickname when he wrote it is “shaped
something like an hourglass.” Others have tagged it the Apple Core Nebula and the Bow Tie Nebula.
Located in the summer constellation Vulpecula the Fox, the Dumbbell is one of the brightest plan-
etary nebulae in the sky. Binoculars and finder scopes reveal it as a rectangular patch of light with a
hint of a tapered waist, floating in a star-studded field 3° due north of Gamma (γ) Sagittae.
With a telescope, use low power to find it, then switch to at least 100x for the best view. Inserting a
narrowband or OIII filter will help accentuate its structural details. The nebula’s brightness is clearly
asymmetrical, with the southern half of the hourglass outshining its northern counterpart. Fainter
perpendicular extensions, which some call ears, protrude away from the center. These are best
appreciated in larger scopes at low power with a contrast-enhancing nebula filter. Centered in all of
this hides a white dwarf, the remnant of the star that gave birth to the nebula some 9,800 years ago.
Shining at 13th magnitude, the white dwarf usually requires at least a 10-inch scope to ferret out.
Each planetary nebula is unique because its appearance depends so much on the angle at which
it presents itself to us. Viewed on-axis, many show nearly circular rings or disks. But viewed from
the side, planetaries can take on long, cylindrical profiles. In the case of the Dumbbell, it is a prolate
spheroid — picture a football with more rounded ends. The bright hourglass shape spans the spher-
oid’s short (minor) axis. The fainter ears align with its long (major) axis. — P. H.
GEORGE CHATZIFRANTZIS42 The Dumbbell Nebula
43 NGC 891
Edge-on galaxies are relatively common
among the thousands visible throughout
the sky. Many even sport dust lanes splitting
their galactic plane, adding visual intrigue.
One such galaxy is NGC 891 in Andromeda.
Finding NGC 891 isn’t difficult. Start with
Almach (Gamma [γ] Andromedae) and move
your telescope 31/2° east. The Silver Sliver
Galaxy, as NGC 891 is also called, is in a rich
star field, which adds to its visual aesthetic.
At magnitude 10.8, this galaxy is visible
with a telescope as small as 3 inches under
excellent skies — but only just. Six-inch or
larger optics are better, and in a 12-inch or
larger scope with dark skies, the spiral’s
disk starts gaining positive superlatives
beyond, “Yep, there it is.” The thickness of
this galaxy’s dark nebulae reduces its visual
contrast with the background sky, making
it harder to see than an edge-on galaxy
without a dust belt. Using averted vision is a
definite advantage here, so try wiggling the
telescope or scanning the field while keep-
ing the galaxy in the corner of your eye.
NGC 891 is classified as Sb, like the
Andromeda Galaxy (M31; see #100). Since
it’s edge-on, astronomers cannot determine
its arm structure. Is it more like M31 or M81?
We will never know. The Hubble Space
Telescope shows that NGC 891’s dust and
gas are distributed into numerous filaments,
like fingers reaching out above and below
the galaxy’s equator. Researchers hypoth-
esize that these filaments were created by a
combination of supernovae and the forma-
tion of energetic massive stars. NGC 891’s
bilateral symmetry shows that it hasn’t
collided with another large galaxy in the last
billion years or so.
Other tidbits of trivia: Hollywood found
the galaxy’s image so compelling that it
appears in the credits sequence of The Outer
Limits — among other objects described
in Astronomy’s June 2019 story “The Outer
Limits universe.” The soundtrack for John
Carpenter’s 1974 film Dark Star included a
track called “When Twilight Falls on NGC 891.”
That same year, Edgar Froese released an
album that included the song “NGC 891.” — A.G.DAN CROWSON