Deepsky Delights
by Magda Streicher
[ magda@pixie.co.za ]
Discover the soul of Messier in the heart of the Milky Way
The Milky Way commands the winter skies, softly spreading its hazy star-cloak against the dark sky. It is then that I know without any doubt that Charles Messier had an all-encompassing love for the night sky. I wonder about his thoughts as he sat, perched on the top of the Hotel de Cluny, pointing his telescope into the rich Milky Way region filled with the most wonderful objects known. Although Messier searched the night sky for comets, these nebulae and clusters must have made a big impression on him and left a life-long memory. Join Messier and let's take up this warm winter tour into the heart of our Milky Way.
Locate 1.8 mag Kaus Australis (epsilon Sagittarii) in the southern corner of the constellation Sagittarius. The first of the three Messier globular clusters, visible with the naked eye, is Messier 69, in the belly of the Sagittarus tea cup, 2.5 degrees north-east of Kaus Australis.
Set against a rich field, M?69 appears as a tiny fuzz ball at medium powers, scattered with star-splinters. Higher power (218x) reveals an uneven wide core, which grows with averted vision to a pin-point core. At the north-western edge an 8 mag star finishes off this globular. Messier was not the only one to see its resemblance to a comet - when Lacaille discovered it in 1752, he described it as similar to "the small nucleus of a comet".
Wander 2.5 degrees further down "globular alley" to M 70, the smallest and faintest of the three Messier globular clusters situated between Epsilon and Zeta Sagittarii. At 76x it shows a small concentrated star-like core covered in the midst of a hazy bubble. High power reveals a sandpaper impression over a prominent nucleus. Brighter stars and a very obvious star chain can be seen on the north-northeastern edge. I wish I could have shared the moment with Mr. Messier when he discovered this globular in August of 1780.
On our way to Zeta Sagittarii the brilliant M 54 can be seen, more distant than its neighbors, but famous for its association with the Sagittarius Dwarf Galaxy. Although it is the farthest of all the Messier globular clusters at a distance of nearly 70 000 light years, M 54 shows up as a blazing light with a large compressed core and wide outer hazy halo with no stars resolved.
The star marking the teapot's lid, Kaus Borealis (lambda Sagittarii) puffs out two more Messier globulars. M 28 is located just one degree north-west of the 2.8 mag golden Kaus Borealis. Although small in size it shows a very dense core embedded in a halo of resolved faint stars. High power (218x) reveals numerous star chains, like flimsy lace, which spread out into a pleasing field of view.
M 22, the "great Sagittarius Nebula", displays all the characteristics of a true showpiece globular. It gives the impression of a well-resolved dense open -cluster, sprinkled with diamond dust, embedded on an uneven hazy patch with no real core. Dark lanes and short strings of various magnitude stars fight their way out into the field of view. On the western edge, some brighter stars stand out. At 218x, a vague dark lane runs from north-east to south-west. If I could discuss the impression of this object with Messier, I would say "Charles, don't you think this is the diamond amongst the crown jewels?"
The cloud of steam that surrounds M 24 (Small Sagittarius Star Cloud) well up north and best viewed with binoculars, shows the way to M 25, which is situated 3 degrees to the south-east. The "cluster" is divided by an uneven dark lane with two streams of stars in each section in an east-west direction. The northern part contains brighter stars as well as the yellow U Sagittarii. About 3 degrees north of the Sagittarius Cloud, M 17 the Swan nebula can be seen. In Messier's words, the "splendor of this bright elongated ESE to NWN glow has the perfect ray or tail of a comet". The northern section is well defined against the background in contrast to the southern wispy hazy part (76x). The western part, however is quite impressive to me; it shows the elegance of the Swan's neck and a sprinkling of faint stars (see sketch below).
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