Sky and Telescope - July 2017 - 57
Going Deep by Ed Mihelich
Seeing Through the Dust
Turning to technology can improve your resolution of globular clusters.
ESA / N ASA / HUBBLE SPACE TELESCOPE
admit it: I'm a globular cluster junkie.
Before I got into amateur astronomy
I'd never heard of these beautiful spherical arrays containing tens to hundreds
of thousands of ancient suns (see S&T:
June 2012, p. 62). Now, nothing quite
matches the real-time visual experience
of a fully resolved globular. But therein
lies the rub. Of the approximately 150
globular clusters in our Milky Way galaxy, relatively few resolve into myriad
stars in standard backyard telescopes.
The problem is not just one of distance,
although the distances to most of these
clusters are enormous. The bigger problem is interstellar dust.
William Herschel thought "the holes
in the heavens" represented an absence
of stars. American astronomer E. E.
Barnard, even with his decades of photographing these "vacuities," was slow
to embrace the concept that interstel-
p DISTANT BRILLIANCE We'll never see the glorious globular cluster NGC 6401 as well as the
Hubble Space Telescope can, but with an assist from night-vision technology, we can improve our
ground-based observations. NGC 6401 lies 35,000 light-years from Earth in the direction of Ophiuchus and typically looks like a round patch of haze in the telescope eyepiece.
lar matter exists and can block more
distant sources of visible light. Today we
know that regions of interstellar dust
dramatically dim the light of distant
stars, and the vast distances to globular
clusters, especially those embedded in
the galactic disk, allow the dust to do
its mischief. As a result, unsuspecting
amateur astronomers excitedly focus
their scopes on stellar prey only to be
greeted by faint cotton balls of light
with no stars resolved. Happily, modern
technology has provided a solution to
Night vision electronics in the guise
of a telescope eyepiece cuts through the
dust as if it were not there. I acquired
p GLOWING GLOBULAR Dennis di Cicco
connected a DSLR camera to his setup to capture this image-intensified view of the globular
cluster NGC 6760 through the eyepiece. The
eyepiece shows stars some two magnitudes
fainter than what he could see through a conventional eyepiece.
s k y a n d t e l e s c o p e .c o m
* J U LY 2 017