M20 is the famous Trifid Nebula, a bright colourful emission and reflection nebula that's located in the constellation of Sagittarius. At magnitude +6.3, it's visible with binoculars. This remarkable object not only contains an emission and reflection nebula but also a dark nebula and an embedded open cluster. When photographed or imaged it looks spectacular, with the emission nebula appearing red, the reflection nebula blue and numerous dark lanes mixed in between. The dark lanes appear to cut through the nebula splitting it into three prominent sections, hence the popular name Trifid, which means divided into three lobes.

The much larger and brighter Lagoon Nebula (M8) is located two degrees south of M20, with tightly packed open cluster M21 positioned 0.75 degrees northeast of M20.

Charles Messier discovered both M20 and M21 on June 5, 1764. He referred to M20 as an envelope of nebulosity. The surrounding area of sky is the richest part of the Milky Way. Here you are looking towards the direction of the galactic centre, hence the abundance of stars, open clusters, globular clusters and nebulae. This wonderful region of sky is perfect to scan with binoculars or small telescopes, especially at low magnifications.

To locate the Trifid, first focus on the bright familiar teapot asterism of Sagittarius. The top three stars of the teapot are Kaus Borealis (λ Sgr - mag. +2.8), Kaus Media (δ Sgr - mag. +2.7) and φ Sgr (mag. +3.2). Imagine a line connecting φ Sgr to Kaus Borealis and then extending it for just over 6 degrees to arrive at M20.

The Trifid is best seen from southern and equatorial regions during the months of June, July and August.

M20 The Trifid Nebula (credit:- ESO)

Finder Chart for M20 (credit:- freestarcharts)

Finder Chart for M20 - pdf format (credit:- freestarcharts)

Finder Chart for M9 (also shown M4, M8, M19->M21, M23, M80 and M107) (credit:- freestarcharts)

Finder Chart for M9 (also shown M4, M8, M19->M21, M23, M80 and M107) - pdf format (credit:- freestarcharts)

M20 is a fine sight in 7x50 or 10x50 binoculars, appearing as fuzzy circular diffuse shape. A small 80mm (3.1-inch) telescope hints at dark lanes spreading from the center of the nebula, especially when viewed under dark skies. With a 150mm (6-inch) or 200mm (8-inch) scope, the Trifid becomes an exciting object. Its irregular shape is visible, along with the trisecting dark lanes, exquisite twists/turns and under good conditions hints of colour. Of course to really appreciate the full beauty of this object an image or photograph is required.

M20 is located 5,200 light-years from Earth and has a spatial diameter of 42 light-years. The dark nebula that gives the Trifid its appearance was cataloged by E. E. Barnard as Barnard 85 (B85) and in 2005 the Spitzer Space Telescope discovered 30 embryonic stars and 120 newborn stars, which had not been seen in visible light images.

M20 Data Table

Messier20
NGC6514
NameTrifid Nebula
Object TypeEmission and Reflection Nebula
ConstellationSagittarius
Distance (light-years)5,200
Apparent Mag.+6.3
RA (J2000)18h 02m 21s
DEC (J2000)-23d 01m 38s
Apparent Size (arc mins)28 x 28
Radius (light-years)21
Other NameCollinder 360

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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