Telescope Reviews: The vast "empty quarter" east of Sagittarius

Once you move east (in rising ascension) past the densely packed heart of the Milky Way in Sagittarius, there is a vast region in the central and southern celestial latitudes that is relatively sparsely populated with bright or interesting deep space objects that extends around nearly to Orion (a span of from about 20h r.a. to about 5h r.a.). It is, of course, an exaggeration to call this region an "empty quarter", and there are islands and pockets of stuff, e.g. the Fornax galaxy cluster, and a scattering of galaxies and planetary nebulae here and there. Nevertheless for example, the descriptive note in the Collins Atlas of the Night Sky for the constellation Cetus quite aptly starts by saying: "While a very large constellation (the fourth largest), Cetus has surprisinly few objects of interest." Capricorn, Aquarius, Aries, and Eridanus share this trait (ok, so Capricorn has a couple of the smaller, dimmer Messier globulars, but but the dense globs in Sagittarius/Ophicus are a hard act to follow and Cap has little in the way of open clusters, nebulae, or galaxies).

That the density of intra-galactic objects should grow sparser east of Sagittarius is hardly surprising, given that the prominent western region of Sagittarius lies astride the central core of the Milky Way, and as one moves eastward in r.a. out of Sagittarius one is progressively moving away from the galactic plane. However, the central/northward region around Ursa Major and extending through Coma Berenices and Leo/Virgo (roughly 10h r.a. to 15h r.a.) also extend sharply away from the galactic plane, and are very richly populated with galaxies (the relative thinness of material from our own Milky Way in this direction helps greatly reduce interference with their visibility).

QUESTION: ARE THERE ANY PARTICULAR REASONS WHY THE CAPRICORN/CETUS et.al. REGIONS ARE RELATIVELY SPARSE OF GALAXIES (from our earth perspective) COMPARED TO THE URSA MAJOR/COMA/LEO/VIRGO REGION? Is this simply a product of where the denser vs sparse filaments of galactic density wound up falling through random processes, or does it also/instead have to do with a much greater amount of obstructing material in the direction of the southern "empty quarter" (if so, shouldn't there be more nebulae?) Or are there still other reasons having to do with differences in orientation of the two respective regions relative to the galactic plane and ourselves?

Maybe there is no better reason than "that's just how matter fell out in this region", or to put it another way, the Virgo region (grand galaxtic cluster closest to us) is centered in one direction from us, not the other, and other dense clusters in other directions are much farther away.

Curious minds want to know.

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Chris M., aka "First Sight"
Orion XT12i Dob with Moonlite CR-2 focuser
WO Megrez 90 refractor on UniStar Light mount
Nikon 10x50 Binoculars

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