M16, also known as the Eagle Nebula, is a young open cluster of stars embedded within an extremely large cloud of interstellar gas and dust in the constellation of Serpens (Cauda). It's located in the next inner spiral arm of the Milky Way, 7,000 light-years distant. The emission part of the nebula or HII region is catalogued as IC 4703 and is an active star-forming region, which has already created a significant cluster of young stars. The cluster itself lies at the heart of the Eagle Nebula and is known as NGC 6611. M16 was discovered by Philippe Loys de Chéseaux in 1745-6, but Charles Messier was the first to record the associated nebulosity on June 3, 1764.

The constellation of Serpens is faint but unique as its split into two separate sections. One half, named Serpens Caput, lies to the west of Ophiuchus and the other half, Serpens Cauda, lies on the eastern side of Ophiuchus. At the very southern tip of Serpens Cauda close to the Scutum and Sagittarius border is M16. It can be found 2.5 degrees west of γ Sct (mag. +4.7) and a few degrees north of the Omega Nebula (M17), M18 and the Sagittarius Star Cloud (M24). This beautifully rich area of the sky is a delight to scan with binoculars.

The Eagle Nebula was immortalised in 1995 when imaged several times by the Hubble Space Telescope. The resulting iconic photograph, titled the Pillars of Creation, showed three magnificent columns of interstellar gas and dust displayed in sensational detail.

M16 The Eagle Nebula showing the Pillars of Creation star forming region (credit:- NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University))

Finder Chart for M16 (credit:- freestarcharts)

Finder Chart for M16 - pdf format (credit:- freestarcharts)

M16 has an apparent magnitude of +6.2, which places it at the very edge of naked eye visibility, but easily within the range of binoculars or small telescopes. A pair of 7x50 or 10x50 models show a faint triangular shaped patch of light along with the brightest cluster stars. Through a 100mm (4-inch) scope roughly 20 stars are revealed, but spotting the emission nebula is much more challenging. Under dark skies the nebula hints at visibility, but due to its low surface brightness, medium to large amateur scopes are better suited to the task. Through 10-inch (250-mm) scopes at low powers, the nebula appears wispy with subtle details including dark obscuring matter to the north along with many more stars visible. To spot the famous Pillars of Creation an instrument of at least 300mm (12-inch) aperture is recommended.

In total, the nebula part of M16 covers 65 x 50 arc minutes of apparent sky with the open cluster spanning 7 arc minutes. This corresponds to spatial diameters of 130 x 100 light-years and 15 light-years respectively. The open cluster is about 5.5 million years old and contains at least 450 stars of which the brightest member shines at mag. +8.2.

M16 is best seen during the months of June, July and August.

M16 Data Table

Messier16
NGC6611 (cluster)
IC4703 (nebula)
NameEagle Nebula
Object TypeEmission nebula with open cluster
ConstellationSerpens
Distance (light-years)7,000
Apparent Mag.+6.2
RA (J2000)18h 18m 48s
DEC (J2000)-13d 48m 26s
Apparent Size (arc mins)7.0 x 7.0 (cluster), 65 x 50 (nebula)
Radius (light-years)7.5 (cluster), 65 x 50 (nebula)
Other NamesCollinder 375, Sharpless 49
Notable FeatureSubject of the famous Hubble Telescope Pillars of Creation photograph

Sky Highlights - March 2017

Comet
Comet 41P/Tuttle-Giacobini-Kresak now visible with binoculars as it heads towards perihelion

Mercury
Mercury heading towards greatest elongation east

Minor Planet
Vesta now visible with binoculars and small telescopes.

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for March 2017

Northern Hemisphere
Evening
West:- Venus (mag. -4.8 to -4.1 - first half of month), Mars (mag. +1.3 to +1.5), Uranus (mag. +5.9), Mercury (mag. -1.5 to -0.4 - second half of month)
Midnight
Southeast:- Jupiter (mag. -2.3 to -2.5)
Morning
Southwest:- Jupiter
Southeast:- Saturn (mag. +0.5)

Southern Hemisphere
Evening
West:- Venus (first half of month), Mars, Uranus
Midnight
North:- Jupiter
East:- Saturn
Morning
West:- Jupiter
Northeast:- Saturn
East:- Neptune (mag. +8.0 - second half of month)

Deep Sky
Naked eye / binoculars:-
Melotte 111 - Mel 111 - The Coma Star Cluster (Open Cluster)
Messier 44 - M44 - The Praesepe (Open Cluster)

Telescopes:-
Messier 67 - M67 - Open Cluster
Messier 51 - M51 - The Whirlpool Galaxy (Spiral Galaxy)
Messier 97 - M97 - The Owl Nebula (Planetary Nebula)
Messier 101 - M101 - The Pinwheel Galaxy (Spiral Galaxy)
Messier 65 – M65 – Spiral Galaxy
Messier 66 - M66 - Intermediate Spiral Galaxy
Messier 95 - M95 - Barred Spiral Galaxy
Messier 96 - M96 - Intermediate Spiral Galaxy
NGC 4244 - Spiral Galaxy
NGC 4565 - Needle Galaxy - Spiral Galaxy

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