Astronomers are always talking about ‘M’ numbers, this and ‘M’ number that so what are these ‘M’ numbers ?

The ‘M’ is short for Messier and refers to in an object from the Messier Catalogue of ‘fuzzy’ objects.  Charles Messier was a French comet hunter who spent his life searching for and studying comets.  While searching the night sky for new comets, Messier kept finding ‘fuzzy’ objects which were not stars, looked like comets but did not appear to move like comets.  To avoid confusion Messier made a list of these ‘fuzzy’ objects so he could avoid them when he was searching for new comets.




Telescopes in Messier’s time were not as good as telescopes of today and even the telescope used by many amateurs today are far better than the best telescopes available in the late 1700’s.  We now know these objects are nebulae, galaxies, star clusters, planetary nebula and super nova remnants.  To Messier these objects were a nuisance, to the modern amateur astronomer they are the things to look for.  Click here to see the table of Messier objects.

There are now many other catalogues of deep sky objects such as the New General Catalogue (NGC Numbers) with millions of objects listed but the 110 Messier objects are still the things most amateur astronomers start observing.

GALAXIES are huge clusters of stars like our milky way galaxy.  Some Messier galaxies are M31 in Andromeda and M65, M66, M95 and M96 in Leo.

OPEN STAR CLUSTERS are groups of between tens to thousands of stars which have formed from a collapsing cloud of gas and dust.  M45 the Pleiades (Seven Sisters) in Taurus is one of the most beautiful of the open clusters.


GLOBULAR CLUSTERS are groups of between a few thousand and about a million stars which form a halo above and below the main disc of our galaxy.  M13 in Hercules is a good example.


NEBULAE are huge clouds of gas and dust which can be seen as hazy patches of light. Some nebulae (nebulae is the plural of the singular nebula), are places where stars can be seen forming. These young stars are particularly active and bright and often illuminate the remaining gas and dust in the nebula around them. M42 in Orion is one such example.


A PLANETARY NEBULA is the remains of a star of about the same size as our star, The Sun.  After about ten billion years the Hydrogen which has powered the star will run out.  The star becomes inflated like a giant balloon.  Eventually the outer parts of the star drift off into space and form a huge bubble.  As we look through the bubble we see more material through the edge so it appears more like a ring.  The Ring nebula in Lyra M57 is the most famous.

SUPER NOVA REMNANTS are the remains of a giant star which has destroyed itself in a massive explosion. One particular type of Super Nova produces a fuzzy patch. This is where a giant star between 5 to 30 times the mass of our Sun reaches the end of its existence.  The star becomes very unstable until it eventually explodes and completely destroys the itself.  The super nova remnant known as the Crab Nebula, in Taurus, is the first in Messier’s list and is therefore designated as M1.


Most amateur start observing using the Messier Catalogue to find suitable interesting objects which are not too hard to find. These pages are intended to help the beginner to astronomy identify what these objects are and what might be seen in binoculars and small telescopes. By clicking on the 'MESSIER LIST' below you can see the list of the 110 objects in Messier's Catalogue. By then clicking on the object number in the first column a page will be displayed giving the details of that object. There are some numbers which do not have object associated with them. These have over the years been identified as errors in the original catalogue, some being listed twice others being stars wrongly identified as non stellar.




Back to Home Page