Astronomy

BINOCULARUNIVERSE

BY PHIL HARRINGTON

66 ASTRONOMY • DECEMBER 2018

C

assiopeia the Queen

is one of the most

distinctive constel-

lations in the sky. Its

five brightest stars

form a W pattern that is easily

recognizable by even the most

casual stargazer.

In Greek mythology,

Cassiopeia was the wife of King

Cepheus, monarch in ancient

Ethiopia. Nearby in our sky is

their only child, Princess

Andromeda, whom we visited

in my last column. Cassiopeia

was banished to the sky after

boasting that Andromeda was

more beautiful than the

Nereids, the female water spir-

its who accompanied Poseidon,

Greek god of the seas.

Cassiopeia forever wheels

around the North Celestial Pole

sitting on her throne, spending

half of her time clinging to it to

keep from falling off.

For most of us, Cassiopeia is

a circumpolar constellation,

and so it graces our skies at

all hours all year long. But

this time of year, she appears

highest in the evening sky.

November is an ideal time to

marvel at the many wonderful

binocular targets that lie

within. There are too many to

visit in a single column, but

here are a few of my favorites.

Let’s begin by centering

on Delta (δ) and Epsilon (ε)

Cassiopeiae in the constellation’s

W. Since these 3rd-magnitude

stars are separated by just

under 5°, they should squeeze

into the same field through

most binoculars.

Just 1° northeast of Delta, we

find open cluster M103, the

final entry in Messier’s catalog

when it was published in 1781

in the Connaissance des temps

for 1784. M104 through M109

were added by 20th-century

astronomical historians after

examining Messier’s unpub-

lished notes.

Messier did not discover

M103, however. Like many ear-

lier entries in the catalog, his

contemporary, Pierre Méchain,

first uncovered it. In this case,

he bumped into it just before

Messier’s catalog was published.

Messier actually never saw it

before his catalog went to press.

Had he the opportunity,

Messier would have seen a spar-

kling collection of stardust set

in an arrowhead pattern mea-

suring about 6' across. Marking

the tip of the arrowhead is the

pretty telescopic multiple star

Struve 131. Most studies con-

clude, however, that the star’s

association with the cluster is

just a chance line-of-sight

alignment. M103 is estimated to

be 8,500 light-years away, more

than four times farther than

Struve 131. Through giant bin-

oculars and telescopes, those

stars look like blue-white sap-

phires surrounding a lone red

stellar ruby near the middle.

If Méchain and Messier had

more time, they undoubtedly

also would have found our next

target. Can you spy another

faint fuzz 2° northeast of M103?

That’s NGC 663, a striking

assembly of about 80 faint stars.

Those stars shine collectively

at 7th magnitude, but remain

unresolvable individually

through 7x to 10x binoculars.

The brightest just peek out

from the glow in my 16x70s.

Even larger binoculars reveal

that the stars appear bunched

into two asymmetric clumps.

NGC 663 actually stands out

better than M103 through bin-

oculars, so be careful not to

confuse one for the other.

Our last stop this month is

NGC 457, set about 2° southwest

of Delta. More than 80 stars call

this cluster home, with many

visible through steadily braced

10x binoculars if you look care-

fully. Viewing through 70mm

and larger binoculars will reveal

that the stars in NGC 457 create

a distinctive pattern. Some

observers imagine a dragonf ly;

others a Hopi kachina doll; or

even Hollywood’s E.T., the

Extraterrestrial. I prefer its com-

mon nickname, the Owl Cluster.

The owl’s body is drawn from

about a dozen stars that shine

between magnitudes 9 and 11,

with two 10th-magnitude suns

marking the tail feathers. Two

arcs, each containing about half

a dozen suns, form the wings.

The east wing is highlighted by

a distinctive 8th-magnitude

orange star, the brightest mem-

ber of the cluster. The owl’s

dazzling “eyes,” marked by

5th-magnitude Phi^1 (φ^1 ) and

7th-magnitude Phi^2 (φ^2 ), are

attention-getters. But don’t

be fooled. Both are probably

foreground stars. NGC 457 is

estimated to be about 7,900

light-years away, while Phi^1 may

lie anywhere from 2,300 to

4,500 light-years away. While

that’s a high potential error, it

still puts them between us and

the cluster. Probably. Still other

data suggest that they could

actually be at the same distance

as the cluster.

Of Cassiopeia, author

Garrett Serviss wrote in his

1888 book Astronomy with an

Opera-Glass, “Here the Milky

Way is so rich that the observer

hardly needs any guidance.”

This still rings true 130 years

later. These three clusters are

just the beginning. By sweeping

the Cassiopeia “W” with your

binoculars, you’ll find treasures

in nearly every field.

Until we meet again next

month, as autumn fades into

winter, remember that when it

comes to stargazing, two eyes

are better than one.

Sighting

the Queen

Cassiopeia offers sparkling

binocular treasures.

The Owl Cluster, NGC 4 57 , is a bright star group shaped in a birdlike form. It features

the bright foreground stars Phi^1 and Phi^2 Cassiopeiae.

The rich open cluster M1 03 appears

as a striking arrowhead-shaped cluster

of glistening stars. ANTHONY AYIOMAMITIS

Some 80 faint stars make up NGC 66 3 ,

a cluster that stands out well from

the Milky Way as seen in binoculars.

Phil Harrington is a longtime

contributor to Astronomy and

the author of many books.

KEN AND E

MILIE SIARKIEWICZ/ADA

M BLOCK/NOAO/AURA/NSF

PETER AND SUZIE ERICKSON/ADA

M BLOCK/NOAO/AURA/NSF