The Caldwell Objects

A quarter-second later, the star ends its life in a
cataclysmic explosion that will shine with the
light of a billion Suns — the luminosity of a small
galaxy. The blast hurls several solar masses of
material outward at speeds measured in
thousands of km per second. Plowing through
space, the ejecta collide with interstellar material,
heating it up and causing it to glow. The ejecta
will continue to expand into space until it fully
dissipates and becomes part of the interstellar
medium. Sprinkled among the fleeing debris are
the newly forged atoms of heavy elements like
gold, silver, and calcium. Many of the keepsakes
we treasure — a wedding band; a greatgrandmother's
silver pendant; an Olympian's
medal; a child's tooth — are made of atoms
dispersed by supernova explosions before our
solar system was born.
Of all the Type II supernovae to have
occurred in our galaxy during recorded history,
the most famous manifested itself on Earth in
A.D. 1054. Chinese astrologers witnessed that
The Caldwell Objects
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event and recorded it as a "guest star" in the
annals of the Sung dynasty. In the 18th century,
the supernova's glowing remnant briefly fooled
Charles Messier into believing he had chanced
upon a new comet. The Crab Nebula, as the
object is known today, became the first deep-sky
object listed by Messier in his famous catalog of
noncometary objects. Next to the Crab, the Veil
Nebula in Cygnus is the supernova remnant
most sought after from midnorthern latitudes,
and it is a perennial favorite at summer star
parties.
Pointing a telescope toward the Veil is easy;
seeing it at the eyepiece may be difficult. Success
depends on your observing site more than
anything else. First locate magnitude-2.5 Epsilon
(ε) Cygni, the star marking the eastern arm of the
Northern Cross. About 3° south of Epsilon Cygni
you'll find the magnitude-4.2 star 52 Cygni. The
fainter, western segment of the Veil (NGC 6960)
virtually "touches" 52 Cygni, running along a
north-south line ever
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