Dr.
Robert Agnew (shown above sitting atop an ancient Mayan observatory in Mexico)
is a Professor of
Music and Humanities at Edison State College in Piqua,
Ohio.
Born in Youngstown,
Ohio,
Robert has a
Masters Degree from Bowling
Green
State
University
and a Ph.D. from Michigan
State
University
Globular
Clusters: Awesome Wonders
of the Night Sky
I
am certainly guilty, in a decade of keeping a night-sky journal, of
using the
word awesome a few too many times. If I count the frequency of the word
as used
with different objects in the heavens, there is no question that it
turns up
with observations of globular clusters more than any other deep-sky
type. A few
examples from my journal
July 2,
2007:
Nearby
to the double star Struve 1931 was the brilliant globular cluster M5,
which at
130X filled the entire eyepiece with a splendid display of stellar
material. An
awesome sight, since it seemed to pulsate and turn as I continued to
observe
it! I was surprised to find I had tracked this object for over an hour,
as it
seemed only a few minutes had elapsed.
December
15, 2004:
Caldwell
80 (NGC 5139), known as Omega Centauri, is the most luminous of all
globular
clusters, with the light output of a million suns! It is only 17,300
light
years away, among the closest globular clusters to us. I came back to
it again
and again - in utter amazement at its royal splendor, like thousands of
colorful jewels set in the heavens - a magnificent crown for a mighty
and
splendid King. Truly an awesome object!
April
14, 2002:
The
globular cluster M15 was ablaze, a beautiful sight under low and medium
magnification. It seemed, like a mandala, to recede back into the
creation of
time and space, becoming deeper and brighter as one probed its
fathomless
depths. The core of this object is like a radiant pearl, with thousands
of tiny
diamonds placed around it. Awesome and hauntingly beautiful!
Globular
clusters can contain as many as a million stars, generally very old
stars,
including red giants and supergiants. Most of the globular clusters
associated
with the Milky Way Galaxy are scattered in a huge swarm around the
nucleus and
are bound, gravitationally, to the galaxy. They are found orbiting a
majority
of galaxies, with some, like the galaxy NGC 7727, having an
extraordinary
amount of globular clusters. The Southern Hemisphere is blessed with
the two
brightest globular clusters, but M13 in the constellation Hercules is a
gem of
the Northern Hemisphere. Though we have only identified around 150
globulars
orbiting the Milky Way Galaxy, a few can be seen with the naked eye,
and a
majority can be observed with a modest backyard telescope.
Globular
clusters are best observed when one has time to contemplate their
beauty. The
stars seem to shift back and forth, or even rotate. This effect is
partly
produced by the fact that many of the stars are very faint, and to the
eye they
appear to blink on and off. Another contributing element is the
Earth’s
atmosphere which, as it moves, can also give the effect of turning dim
stars on
and off. Consequently, there is a sense of motion in observing a
globular
cluster that few night-sky objects can rival.
If
you are patient, and willing to examine a globular cluster at length,
it will
not disappoint!
As
the great English poet John Keats wrote in his poem
When I
Have Fears
“When I behold, upon the night's starr'd face,
Huge cloudy symbols of a high romance ...”
He
seems to beckon us to observe the romantic - the awesome - globulars!
©
Article &
image Dr. Robert Agnew 2008/2009