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Paddling the Pebbly River

by Geoff Chester | 31 July 2024

by Geoff Chester | 31 July 2024


Messier 17, the "Swan Nebula" in Sagittarius, imaged on 2024 July 28 UT
from Sky Meadows State Park, Paris, Virginia
with a ZWO Seestar S50 Smart Telescope

Early risers can catch the waning crescent Moon before dawn passing through the rising constellations of winter.  Luna returns to the evening sky by the end of the week, following New Moon, which occurs on August 4th at 7:13 am Eastern Daylight Time.  Look for Luna’s slim crescent near the bright Twin Stars of Gemini, Castor and Pollux, in the gathering morning twilight on the 2nd.

The July campaign for the citizen-science Globe at Night program continues until August 4th.  The focus of this month is the constellation of Cygnus, the Swan, one of the signature constellations of the summer sky.  Cygnus is easy to find.  Its brightest star, Deneb, is the northernmost and faintest of the three bright stars that make up the Summer Triangle asterism.  You will find the Triangle rising in the eastern sky at the end of evening twilight.  Deneb marks the Swan’s “tail”, and its long neck stretches to the center of the Triangle, ending with the star Albireo.  Under suburban skies you can trace out the bird’s “wings”, and under dark skies it only takes a small bit of imagination to trace out a stick-figure swan, seemingly flying southward along the Milky Way.  To contribute to the Globe at Night database, go to the site’s web app, where you will be presented with star charts to help you determine the faintest stars that you can see with the naked eye.

Last week we looked at the Greco-Roman sky lore about the Swan, but one of my favorite ideas depicted by the constellation comes from the Inuit of the arctic north.  To them the Swan depicted a man in a kayak paddling along what they called the Pebbly River, another very apt description of the Milky Way.  

If you follow the Pebbly River to the northeast, you will run into the “W-shaped constellation of Cassiopeia, the Queen.  While our western mythology incorporates the group into a complex tale of vanity, revenge, and deliverance involving several surrounding constellations, once again the Inuit had an elegant idea of what these stars represented from their environment.  Their view was of five reindeer drinking from the Pebbly River.  At their latitude the reindeer were in the sky all night year-round, so perhaps seeing them in the sky was a sign of successful hunts for sustenance in that harsh landscape.

Use binoculars to sweep the Milky Way from Cassiopeia, through Cygnus, and southward to the horizon.  Under dark skies you will pass clouds of innumerable stars, punctuated by knots of star clusters and glowing gas clouds.  These indicate that our Galaxy is continually evolving, creating new stars in the gas clouds as older stars disperse from the clusters.  The center of the Galaxy lies veiled behind dense clouds of gas and dust just off the tip of the “spout” of the teapot asterism in Sagittarius.  Here your binoculars will show a spectacular cluster first described by Ptolemy in his second-Century work, the “Almagest”.  The span of the Milky Way between Ptolemy’s Cluster and the Summer Triangle is also a treasure trove for owners of small telescopes.  Many of the most popular “deep sky” objects on amateur observing list may be found in this region.

Saturn now rises at around 10:00 pm, and by midnight he’s high enough to get a first look through the telescope.  I was out with my 8-inch Newtonian last weekend, and got my first peek at the ringed planet for this year.  The planet’s rings look like bright spikes poking out from the sides of the disc.  Get used to this view; the rings will be edge-on to our line of sight next year, and the familiar appearance of the rings won’t return until 2026.

Ruddy Mars continues to chase bright Jupiter down in the early morning sky.  If you are out at 5:00 am you can catch the pair among the stars of Taurus, the Bull.  Mars will catch old Jove and pass him next week.

 
 

Commander, Naval Meteorology and Oceanography Command | 1100 Balch Blvd. | Stennis Space Center, Mississippi 39529

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