Fred Schaaf
SkyandTelescope.com September 2014 47OBSERVING
Northern Hemisphere’s SkyFred Schaaf welcomes your
comments at [email protected].How do you know but ev’ry Bird that cuts the airy way,
Is an immense world of delight, clos’d by your senses fi ve?
— William Blake, The Marriage of Heaven and HellAs summer ends, I know one bird that cuts not the airy
but the starry way. Its name is Cygnus the Swan.
Aquila the Eagle has its attractions, rich little Lyra the
Lyre has also been called the Swooping Vulture, and the
sky contains a half dozen other bird constellations, both
ancient and modern. But the wonders of Cygnus exceed
all of them, both in number and variety. Cygnus is an
immense world of delight for the sense of sight. Or rather,
it is a multitude of magnifi cent worlds, each one diff erent
from the next.
Gloriously diverse Cygnus. What other constella-
tion off ers for the amateur telescope one of the sky’s most
dramatic supernova remnants (the Veil Nebula) and also
one of its most vivid planetary nebulae (NGC 6826, the
“Blinking Planetary”)? But that’s just the beginning.
Cygnus also brings us a huge naked-eye emission nebula
(the North America Nebula, described on page 56), which
may be energized by the most luminous star within a few
thousand light-years of Earth (Deneb).
The Veil Nebula itself is so diverse in its various sec-
tions that its components have been rewarded with a
whole slew (or rather bouquet) of names: the Filamentary,
Cirrus, Network, Lacework, and Bridal Veil nebulae. Parts
of the Veil can be glimpsed through 10×50 binoculars in
dark skies. At the other extreme, 16-inch telescopes may
start showing you the Veil’s colors, and structures that
could spawn even more names. One section of the Veil
reminds me of a luminous tornado.
The best of light and dark. Another aspect of Cyg-
nus’s diversity is the radiant Cygnus Star Cloud right next
to the sky’s largest chain of dark dust clouds. The Cygnus
Star Cloud is a wreath of mist that the bird’s straight neck
shoots through, so bright and high in the sky from mid-
northern latitudes that it’s sometimes faintly visible even
in urban or suburban skies where the limiting magnitude
is 5.0 or worse. The Great Rift is the dark division that
splits the Milky Way band in two all the way from Cygnus
to far-southern Centaurus. Its interstellar dust begins not
far from Deneb, in a region sometimes called the North-
ern Coalsack — named after the smaller but more intense
Coalsack in the far-southern sky. Appropriately, thetrue Coalsack is adjacent to the Southern Cross, and the
Northern Coalsack lies next to the Northern Cross, which
is formed from the Swan’s fi ve brightest stars.
A bird that cuts the Milky Way. The Rift cuts longi-
tudinally down the Milky Way’s luminous band, but the
great dust cloud called Le Gentil 3 cleaves most of the way
across the Milky Way northeast of Deneb.
Another thing that cuts across the Milky Way —
almost completely — is the chain of stars that forms
Cygnus’s full wingspan. Cygnus can be said to be in sev-
eral diff erent kinds of fl ight. Its main pattern, the Swan,
appears to fl y almost directly down the Milky Way band
— that is, to the southwest (appropriate in this season
when birds are migrating south at northern and mid-
northern latitudes). But when we stare at Cygnus’s more
distant stars — especially those of the glorious Cygnus
Star Cloud — we’re looking ahead in the direction that
our part of the galaxy rotates. Our local neighborhood of
stars is fl ying more or less toward these distant reaches of
Cygnus, while Cygnus’s stars fl y on ahead.
Our personal fl ight with Cygnus is not over yet. Next
month here we’ll explore many more of the diversities and
motions of the starry sky’s most wondrous bird. ✦The Bird of the Starry Way
Cygnus is a source of endlessly varied delight.
This false-color ultraviolet image
from the GALEX spacecraft reveals
amazing detail in the Veil Nebula.
NASA / JPL-CALTECHNHS.indd 47 6/23/14 12:18 PM