Sky & Telescope - August 2020 - 23

S GLORIOUS LAGOON The author's logbook from the second night at the OSP reads: "Lots of contrast for the nebulosity, and even with the soft
seeing this is a wonderful view! The SQM is reading 21.95 now and the sky in general is awesome - the Milky Way is wide and granular. Anyway, the
Hourglass area in the Lagoon is a wonderland of soft nebulosity shading from bright to barely visible, great stuff. I've worked on both sketches for the
past hour and a half - I've had a great time!" The author carefully recorded stars within the boundaries of the nebulosity and omitted the vast majority
of the rich Milky Way star fields surrounding the Lagoon. There were subtle hints of a warm hue in the bright central areas, but no definite reddish
tones. Note the prominent dark channel running through the central region of the nebula.

nebulosity of the Lagoon, which is really the only way we can
detect them, especially the smaller ones. Usually not much
more than about 1 light-year across, Bok globules commonly
give rise to multiple star systems.
Experiment with different magniﬁcations on your scope
to ﬁ nd the best view of these dark blobs. Be sure to use a
UHC or O III ﬁ lter if you observe under a less-than-pristine
sky. I found a magniﬁcation of around 100× works best on
my 8-inch, which also excludes the Triﬁd Nebula from the
ﬁeld of view, making the Lagoon easier to concentrate on.
For my 28-inch scope I like to use a magniﬁcation of 408×.
Take your time at the eyepiece and see how many of these
dark cloudlets you can detect.

HOWA RD BA NICH

Looking Around
Nebulosity in the faint outer reaches of the Lagoon was the
most surprising feature I saw, especially since I didn't use
a nebula ﬁlter. Filters greatly increase the visual size of the
nebula and show much the same detail as the image on page
20 fairly well, but that doesn't mean the fainter nebulos-

ity was an easy catch. I clearly saw it on only the best nights
while I was purposely scanning the extreme edges of M8.
The low-power drawing also illustrates the overall texture
and structure of the Lagoon. The bright central area west of
the dark channel shows a circular ﬂowing pattern, while the
surrounding outer areas are more of a patchwork of soft glows
and dark areas. Interestingly, studies have shown the Lagoon
is generally expanding from the Hourglass region outward
in all directions and that a thin sheet of warm gas is moving
toward us from its near edge. The thinner areas allow for a less
obstructed view of this brightest part of the Lagoon.
Perhaps this implies that radial pressure is pushing gas
and dust outward from the two main stars that power the
glowing nebula - 9 Sagittarii (9 Sgr) and Herschel 36
(Her 36). If so, it seems the dark channel is really more of a
compression feature.

The Close-up View
Let's move to the detailed drawing showing the region west of
the dark channel, and the area around the Hourglass, where
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Sky & Telescope - August 2020

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