Astronomy

54 ASTRONOMY • JANUARY 2018

direction along the nebula’s 30'-by-20'
length while keeping your eyes relaxed and
your mind alert. The nebula’s most promi-
nent portion is a kite-shaped wedge
extending southeast from AE, followed by
a long, thin streamer that runs along the
nebula’s northeastern edge.
If you are under a dark sky, use 10x50
binoculars to scan about 1 ̊ southeast of
the leaping minnow, and see if you can
detect the soft and tiny (12') glow of the
magnitude 7.5 cluster NGC 1893 that illu-
minates the surrounding 20'-wide diffuse
emission nebula IC 410. I mention this
latter object specifically for astroimagers
because the nebula reminds me of a little
Rosette Nebula and is part of the larger
one that lies at the core of the Auriga OB2
association. The embedded cluster has
about 20 members, the brightest of which
shine around 9th magnitude and dip down
to about 13th.

SAID THE SPIDER
TO THE FLY...
If you’re out admiring M36 and M38 with
binoculars, look for two curious threads

of starlight that seem to connect the two

clusters to 5th-magnitude Phi (φ) Aurigae,

an orange K-class giant flanked by two

6th-magnitude attendants. As a whole, this

star-and-cluster stream forms an open V

asterism that New York City skywatcher

Ben Cacace refers to as the Cheshire

Cat (an allusion to Alice’s Adventures in

Wonderland).

Now peer at Phi Aurigae through a

larger looking-glass — your telescope. That

crisp, golden star has numerous fainter

stars sprinkled around it from northeast to

southwest, while a smaller collection of

jewels hugs Phi to the southeast.

All these stellar gems belong to the

largely “silent” Stock 8 — a 2 million-year-

young cluster embedded in its nascent neb-

ula IC 417, which washes through the

entire region. Wide-field imaging reveals

that IC 417 is a vast cloud of glowing

hydrogen with long, spindly legs that

stretch across 1½° of sky. When Boston

amateur astronomer Steve Cannistra

scanned one of his wide-field images of the

region, he nicknamed IC 417 “The Spider,”

and our next target — the tiny (4')

nebulous cluster NGC 1931 (about 5' to the

east-southeast) — “The Fly.”

NGC 1931 is a beautiful little cluster

that’s easily seen through small scopes.

Only 10 million years old, the cluster is

7,000 light-years distant — or about five

times farther away than the Orion Nebula,

of which it is a remarkable miniature.

Telescopically, at low power and with

direct vision, NGC 1931 is so dense that it

appears like a fuzzy star. With averted

vision, however, it immediately swells

into a distinct nebulous knot. The trick

to seeing the cluster within is to use high

magnification (start with 165x and work

your way up) to resolve its central triad of

suns. Concentration will bring out several

other fainter jewels. But these may swim

in and out of view as you move your eye

while using averted vision and pass over

the nebulosity, which is brightest on the

southern side. The stars appear to be

embedded in knots or nebulous folds,

from which thinner tendrils stream —

including a graceful sweep of ref lection

nebulosity stretching southward from

the main nebula.

Open cluster M37 Open cluster M38

Emission nebula IC 417 Emission nebula NGC 1931

CLOCKWISE FROM UPPER LEFT:

ADAM BLOCK/MOUNT LEMMON SKYCENTER/UNIVERSITY OF ARIZONA; ANTHONY AYIOMAMITIS; MARK HANSON;

MARTIN C. GERMANO; AL AND ANDY FERAYORNI/ADAM BLOCK/NOAO/AURA/NSF; ADAM BLOCK/NOAO/AURA/NSF