Constellation - Capricornus

Constellation - Capricornus


Capricornus, the Sea Goat is one of the constellations of the zodiac. It is often known as Capricorn. Constellations of the zodiac all lay along the ecliptic line. This is the line that the sun, moon and planets follow across the sky. Capricornus was named in Ptolemy's 48 original constellations and remains in the current 88 official constellations. It is the second faintest of the zodiac constellations with Cancer being the faintest. It does however, have the honour of being the smallest of the zodiac constellations. 

The meteor shower associated with Capricornus is the Capricornids that peaks on July 30th and achieves a rate of around 20-30 meteors per hour.


Capricornus in Greek mythology is thought to represent the goat that fed Zeus when he was a baby. Zeus was saved from his father, Cronos by his mother, Rhea and Amalthea was the goat that fed him. The goat's broken horn is said to have become the horn of plenty.

However, the constellation is probably much older than this. Images of the sea goat have been found dating back 3,000 years. At this time the winter solstice occurred in Capricornus. 

Take the Tour:

Number Object Description Magnitude Surface Brightness
1 M72 Globular Cluster 9.2 12
2 C55 Planetary Nebula 8.3 6.2
3 M30 Globular Cluster 6.9 11
4 M75 Globular Cluster 8.6 11
5 C57 Galaxy 8.8 14.5

Each image is the size of a full moon for size comparison.



Messier 72 is a globular star cluster located about 55,000 light years away. It was discovered by Mechain in August 1780. This is a difficult to observe cluster that requires dark skies to resolve some of the 168,000 stars contained within. It has a very high luminosity for a globular cluster which is why it is visible at all from such a distance away. However, keep looking for it as it is travelling towards us at around 300 km/hr so may become easier to see one day.

C55, The Saturn Nebula:


Caldwell 55 or NGC 7009 is an easy to observe planetary nebula. This is a special object to see and is high on amateur astronomers list of must see objects. It takes the name of the Saturn nebula as it appears to have rings resembling the appearance that Saturn has in the eyepiece. It is found about 3,000 light years away and was discovered by Herschel in September 1782. Make sure you don't miss one of the nine 'rare celestial objects'



Messier 30 is a globular cluster found about 28,000 light years away. It was discovered by Charles Messier in August 1764. This can be quite a difficult cluster to find. The easiest way is to spot the two stars in Capricorn that are close to each other. However, this cluster is observable with good binoculars. A four inch telescope will start to resolve stars in the cluster. M30 was probably picked up by the Milky Way from a satellite galaxy as it follows a retrograde orbit. This cluster is special as it has undergone a core collapse which makes it one of the densest places in the Milky Way.



Messier 75 is another globular cluster located 67,500 light years away. It was discovered by Mechain in August 1780. This is a distant globular which makes it not much bigger than a star in the eyepiece. It can be a difficult globular to spot and requires dark skies ideally to find. A large telescope is needed to resolve the stars and in a mid-sized telescope it will appear grainy. 

C57, Barnard's Galaxy:


Caldwell 57 or NGC 6822 is a barred irregular galaxy located 1.6 million light years away. It was discovered by Barnard in 1881. This galaxy is a close neighbour to our own Milky Way and resembles the Small Magellanic Cloud in its appearance. With a surface brightness of 14.5 it is a challenge to observe.

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