M68 is a magnitude +7.8 medium size globular cluster located in eastern Hydra that was discovered by Charles Messier on April 9, 1780. Although not as spectacular as other globulars such as Omega Centauri, 47 Tucanae or M13, it's easily visible with 7x50 or 10x50 binoculars where it appears obviously non-stellar. For owners of medium and large size amateur scopes this is quite a rewarding object.

Hydra is the night sky's largest constellation. However, despite it's great apparent size it contains only one reasonably bright star, Alphard (α Hya - mag. +2.0). Still locating M68 is quite easy since it's positioned just south of the relatively bright quadrangle of Corvus and 3.5 degrees southeast of star β Corvi (mag. +2.6).

Due to its declination of -26.7 degrees, M68 is best seen from the Southern Hemisphere during the months of March, April and May. From northern temperate locations it never climbs very high above the horizon.

Messier 68 globular cluster by the Hubble Space Telescope (credit:- NASA, The Hubble Heritage Team (AURA/STScI))

Finder Chart for M68 (credit:- freestarcharts)

Finder Chart for M68 - pdf format (credit:- freestarcharts)

Through a small 80mm (3.1-inch) telescope, M68 shows a bright centre surrounded by a fuzzy halo that gradually fades to the edges. On nights of good transparency and seeing the outer parts of M68 are resolved with a 200mm (8-inch) reflector. The core is not compact and amateur scopes of the order of 300mm (12-inch) or greater will resolve stars across the complete cluster face. In total, M68 spans 11 arc minutes of apparent sky although it appears somewhat smaller through the eyepiece.

M68 is located approximately 33,000 light-years distance. It has a spatial diameter of about 105 light-years and is estimated to contain more than 100,000 stars.

M68 Data Table

Messier68
NGC4590
Object TypeGlobular cluster
ConstellationHydra
Distance (light-years)33,300
Apparent Mag.+7.8
RA (J2000)12h 39m 28s
DEC (J2000)-26d 44m 34s
Apparent Size (arc mins)11 x 11
Radius (light-years)53
Age (years)11.2 Billion
Number of Stars>100,000
Notable FeatureRelatively metal poor cluster

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

Southern Hemisphere
Evening
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
Midnight
West:- Jupiter
North:- Saturn
East:- Neptune
Morning
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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