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

Object TypeGlobular cluster
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 - July 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for July

Meteor Shower
Southern Delta Aquariids (Aquarids) meteor shower peaks on July 29

Northern Hemisphere
West:- Mercury (mag. -0.5 to +0.3) (second half of month)
Southwest:- Jupiter (mag. -2.0)
South:- Saturn (mag. +0.2)
West:- Jupiter
South:- Saturn
East:- Neptune (mag. +7.8)
Southwest:- Saturn
South:- Neptune
Southeast:- Uranus (mag. +5.8)
East:- Venus (mag. -4.1)

Southern Hemisphere
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
West:- Jupiter
North:- Saturn
East:- Neptune
West:- Saturn
North:- Neptune
Northeast:- Venus, Uranus

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

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