M80 is a small but compact globular cluster located in Scorpius. It shines at magnitude +7.5 and therefore within the range of popular 7x50 or 10x50 binoculars. At its core, M80 contains a large number of "blue stragglers", stars that appear much younger than the age of the globular cluster itself! The likely reason is they have probably lost part of their cooler outer layers due to close encounters with other stars. Since M80 contains more blue stragglers than average it implies exceptionally high core stellar interaction rates.

M80 was discovered by Charles Messier on January 4, 1781. Though not conspicuous, M80 is easy to locate as its positioned just 4 degrees northwest of brilliant red supergiant star Antares (α Sco - mag. +1.0). The globular is situated halfway along an imaginary line connecting Antares with Acrab (β Sco - mag. +2.6). Located just west of Antares is magnificent globular cluster M4.

The finder chart below shows the position of M80. The globular is best seen from tropical and Southern Hemisphere latitudes during the months of May, June and July.

M80 globular cluster by the Hubble Space Telescope (NASA, The Hubble Heritage Team (AURA/STScI))

Finder Chart for M80 (also shown M4, M6, M9, M19 and M62)

Finder Chart for M80 (also shown M4, M6, M9, M19 and M62) - pdf format

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

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

When viewed with binoculars or small telescopes, M80 appears as a mottled ball of light. A small 80mm (3.1-inch) scope reveals a soft round structure that's not resolvable. Larger 200mm (8-inch) telescopes display a bright compact core and an outer halo that extends up to 5 arc minutes in diameter. On nights of good seeing and transparency the outer regions hint at resolution. Much better resolution is achieved with apertures of 300mm (12-inch) or greater, with the brightest member stars being of about 14th magnitude. On May 21, 1860 a bright nova (T Sco) reached magnitude +7.0 in M80 and for a short time it outshone the entire cluster.

M80 is located at a distance of about 32,600 light-years and contains at least 200,000 stars. In total it covers 10 arc minutes of apparent sky, which corresponds to a spatial diameter of 96 light-years. The cluster is estimated to be 12.54 billion years old.

M80 Data Table

Messier80
NGC6093
Object TypeGlobular cluster
ConstellationScorpius
Distance (kly)32.6
Apparent Mag.7.5
RA (J2000)16h 17m 03s
DEC (J2000)-22d 58m 30s
Apparent Size (arc mins)10 x 10
Radius (light-years)48
Age (years)12,540M
Number of Stars>200,000
Notable FeatureContains a relatively large number of blue stragglers

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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