The Messier Objects

Charles Messier (1730–1817) was a French astronomer who had an obsession with comets. Getting fed up with discovering fuzzy blobs that turned out to be distractions, he made a catalogue of things to avoid in the night sky. His assistant and friendly rival Pierre Méchain assisted him in this task, and eventually he compiled a list of 103 objects. Later astronomers extended the list to 110 objects, though M102 is considered by many to be a duplicate entry.

Well, that's almost ten times as many objects as the number of comets he actually found, and the irony is that Messier's comets faded back into the obscurity of the outer solar system, while his list remains a favourite guide to many of the finest sights in the night sky!

The list includes several types of object, mostly globular clusters, open clusters, planetary nebulae and galaxies. Most are telescopic objects, but several can be seen with the naked eye, especially from dark sky sites. Here are some examples from the list:

	M1 Catalogue number: M1 Friendly name: Crab Nebula Constellation: Taurus Distance from Earth: ~6,500 light-years Size/Diameter: ~11 light-years across Object type: Supernova remnant M1 is the remnant of a supernova explosion observed by astronomers in 1054 AD — bright enough at the time to be seen in daylight. The tangled filaments of expanding gas visible here are still spreading outward at around 1,500 kilometres per second. At its core lies a pulsar, a rapidly spinning neutron star making one full rotation 30 times every second.
	M13 Catalogue number: M13 Friendly name: Great Hercules Cluster Constellation: Hercules Distance from Earth: ~25,000 light-years Size/Diameter: ~145 light-years across Object type: Globular cluster M13, the Great Hercules Cluster, one of the finest globular clusters visible from the northern hemisphere. It contains around 300,000 stars packed into a roughly spherical formation, with the core appearing as a dense, brilliant concentration of starlight. The cluster is estimated to be around 11.65 billion years old, making it nearly as old as the universe itself.
	M27 Catalogue number: M27 Friendly name: Dumbbell Nebula (also known as the Apple Core Nebula) Constellation: Vulpecula Distance from Earth: 1,300 light-years Size/Diameter: 3 light-years across Object type: Planetary nebula M27, the Dumbbell Nebula, one of the brightest planetary nebulae in the sky. It formed when a sun-like star reached the end of its life, ejecting its outer layers of gas before collapsing into a white dwarf — visible at the centre of the nebula. The distinctive double-lobed shape, with knotty clumps of gas still expanding outward, is clearly visible here
	M42 Catalogue number: M42 Friendly name: Orion Nebula Constellation: Orion Distance from Earth: ~1,344 light-years Size/Diameter: ~24 light-years across Object type: Emission/reflection nebula (stellar nursery) M42, Located in Orion's sword the Orion Nebula, one of the most studied and photographed objects in the night sky. It is an active stellar nursery where new stars are currently forming from collapsing clouds of gas and dust. At its heart lies the Trapezium, a tight grouping of young, hot stars whose radiation illuminates the surrounding nebula
	M51 Catalogue number: M51 Friendly name: Whirlpool Galaxy Constellation: Canes Venatici Distance from Earth: ~23 million light-years Size/Diameter: ~60,000 light-years acrossObject type: Spiral galaxy (interacting) M51, the Whirlpool Galaxy, a striking spiral galaxy in the process of interacting with its smaller companion, NGC 5195, visible at the end of one of its spiral arms. The gravitational interaction between the two galaxies has helped define M51's well-structured spiral arms, making it one of the most photogenic galaxies in the sky.
	M81 & M82 Catalogue numbers: M81 / M82 Friendly names: Bode's Galaxy / Cigar Galaxy Constellation: Ursa Major Distance from Earth: ~12 million light-years (both)Size/Diameter: M81 ~90,000 light-years \| M82 ~37,000 light-yearsObject type: Spiral galaxy / Irregular starburst galaxy This image captures M81 and M82, two interacting galaxies in Ursa Major. M81, on the right, displays well-defined spiral arms wrapped around a bright central core. M82, on the left, is seen edge-on and shows striking red filaments of hydrogen gas being driven out from its core — a direct result of gravitational disruption caused by its close relationship with M81. This interaction has triggered an exceptionally high rate of star formation in M82. The light captured here left both galaxies around 12 million years ago, long before the first members of the human family walked the Earth

All images on this page with the exception of M1 were captured by members of the Rosliston Astronomy Group's Astrophotography Special Interest Group. M1 was captured my the Moana Project. this is a source of free data on which you can practise your editing skills. Fancy joining us?