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September Night Skies

If we’re lucky for clear skies, September nights in the Southern hemisphere would give us the sky objects which mostly lie in and near Sagittarius over head.  Take a look at the following Messier objects you can find with your telescope. 

M24 (The MIlky Way Patch), M8 (The Lagoon nebula), M20 (The Trifid nebula), M7 (The Ptolemy’s cluster), M6 (The Butterfly cluster), M17 (Horseshoe nebula), M16 (The Eagle nebula), M22 (Globular cluster) and M11 (The Wild Duck).

 

M24 is a huge star cloud in Milky Way, a pseudo-cluster of stars spread thousands of light years along the line of sight, perceived through a chance tunnel in the interstellar dust.  In 1905, Fr. Secchi named this Milky Way patch “Delle Caustiche from the peculiar arrangement of its stars in rays, arches, caustic curves, and intertwined spirals.” The stars, clusters and other objects of M24 form a portion of a spiral arm (the Sagittarius or Sagittarius-Carina arm) which fills a space of significant depth, at a distance of 10,000 to 16,000 lightyears.  This starcloud is easily located with naked eye above the teapot asterism and north of Mu Sagittarii.

 

 M8 or The Lagoon nebula is estimated at 5200 lightyears away.  It is a giant cloud of interstellar matter which is currently undergoing vivid star formation, and has already formed a considerable cluster of young starts.  The brightest part of the Lagoon Nebula is called the “Hourglass Nebula.”

M20 or The Trifid Nebula is famous for its three-lobed appearance.  The red emission nebula with its young star cluster near its center is surrounded by a blue reflection nebula which is particularly eye-catching to the northern end.  It is estimated at 5200 lightyears away.

 M7 or The Scorpion’s Tail, or mostly known as Ptolemy’s Cluster is a large and brilliant group that can easily be detected with the naked eye. Ptolemy described it in 130AD as the “nebula following the sting of Scorpius.”  The cluster’s age is estimated at 220 million years and consists of about 80 stars brighter magnitude 10 in a field of about 1.3 degrees apparent diameter which at is distance of perhaps 800 lightyears.

 M6 or The Butterfuly cluster is described as a “charming group whose arrangement suggests the outline of a butterfly with open wings.”  It is estimated at 1600 lightyears away with 100 million years estimated age. It is situated at the closest angular distance from the Galactic Center, which is located in the constellation Sagittarius but very near to the 3 constellation edge of Sagittarius, Scorpius and Ophiuchus.

 M17or The Omega Nebula, also referred to the Swan Nebula, the Horseshoe Nebula, or the Lobster Nebula is another region of star formation and shines reddish with some graduation to pink which comes from the hot hydrogen gas emitted by the newly formed hottest stars within the nebula.  Estimated at 5000 lightyears away can be found easily and simultaneously with its neighbor M16.

 M16 The Eagle Nebula is another region of active star formation.  It lies perhaps or say estimated at 7000 lightyears away in the constellation Serpens, close to Scutum and Sagittarius.

 

  M22 has an estimated count of 70,000 stars and one of the brightest globular clusters in the sky particularly to those from mid-northern latitudes.  Discovered in 1665 by Abraham Ihle, it is estimated at 10,400 light years, visible to the naked eye as it is brighter than M13.

  M11or  The Wild Duck cluster in the Scutum (between Sagittarius and Altair) is approximately 220 million years old and 6000 lightyears away.  It contains an estimated 2900 stars, 500 of which are brighter than magnitude 14.  It is one of the richest and most compact of the galactic open clusters.

On the west, Virgo sets down with M5 globular cluster on celestial equator.  While on the east, arise 3 globular clusters namely M15 near Pegasus, M2 in Aquarius and M30 in Copernicus.

 M2, discovered on September 11, 1746 by Maraldi, was described as a “nebula without stars.”  It was resolved by William Herschel. M2 is a compact globular cluster which contains about 150000 stars.  It is difficult for the naked eye to see but can be an easy target if with binoculars or even opera glasses.  It lies within constellation Aquarius – from Alpha and Beta Aquarii, as well as Epsilon Pegasi and approaching us at the low velocity of 5.3 km/sec.

 M30 in Copernicus is about 26,000 light years away and has a core with an extremely dense stellar population.  It was originally discovered by Charles Messier on August 3, 1764 and also described it as round nebula, containing no stars.  It was again first resolved by William Herschel around 1784.  This nebula because of its location in the sky is usually an interesting object for amateur astronomers.

 

The Northern view near Vulpecula and Lyra lie M27 Dumbbell nebula, M57 Ring nebula, M56 globular cluster.  M92 globular cluster and M13 or The Hercules globular cluster  are both visible on the northern hemisphere as well.

 

  M27 or The Dumbbell Nebula, perhaps the finest planetary nebula in the sky, is among the brightest.  The estimated distance is 1200 light years away with the luminosity of about 100 times that of the Sun.  Other estimates that were given range from 490 to 3500 light years away.

  

  M57 or The Ring nebula, often regarded as the prototype of a planetary nebula, is an attraction in the northern hemisphere summer sky, estimated at 2300 lightyears away.

 M56, a less bright globular cluster, is located between Albireo and Lyra. It is estimated at 32900 lightyears and was discovered by Charles Messier on January 23, 1779, described it as a “nebula without stars,” and again was resolved by William Herschel in 1784.  It is approaching us at the high velocity of 14 km/sec.

 

  M13 is also called the “Great globular cluster in Hercules.”  In absence of the Moon, this globular cluster shows itself to the naked eye on the northern celestial hemisphere.  It is 25,100 light years away and perhaps contains about 100,000 to a million stars.  Its age is estimated at 24 billion years.

 

 M92 is another interesting globular cluster located in constellation Hercules, second to that of M13.  It is about 26,000 light years in distance and a bit younger than M13, about 16 billion years.  It is also visible to the naked eye, less brighter than M13.  It is approaching us at 112 km/sec.  It might be interesting for one to know that the Earth’s North Celestial Pole occasionally passes closer than 1 degree of this cluster at periods of the precession of Earth’s axis which happens about every 25,800 years.  So this cluster becomes a “Polarissima Borealis,” or “North Cluster,” in about 14,000 years (16,000 AD), as it was about 12,000 years ago (10,000BC). 

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Tags: Eagle, globular clusters, Messier objects, Milky Way, nebula, Polarissima Borealis, Ptolemy, Sagittarius, Trifid
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