Solar System

(The Queen)

The unmistakable 'W' shape of Cassiopeia is visible on most clear nights in the year. The reason for being in the sky for more than one season is because it is in close proximity to the celestial north pole. At the centre of the pole is Polarus, the Pole Star and everything that is near the pole appears to rotate around this star.

Sometimes this 'W' is upside down in autumn and looks like a celestial letter 'M'. It is hard to imagine this figure being a queen sitting on a throne but ancient people managed to.

Cassiopeia in mythology is most noted for proclaiming her beauty being greater than everyone else but she had other moments of glory such as stating that "Perseus must die" when his army fought the army of Agenor, one of Poseidon's sons. Perseus and Cassiopeia's daughter Andromeda were due to marry each other but the nefarious Cassiopeia plotted against Perseus and she wished Andromeda to marry Agenor. Agenor with a mighty army to showcase his strength attempted to claim Andromeda for his own but the noble Perseus was willing to thwart him. Eventually the battle between Agenor's and Perseus' armies was concluded and Perseus emerged as the victor and Cassiopeia was turned to stone along with her husband Cepheus the King with the head of the Gorgon Medusa.

It is quite apt that this constellation is somehow related to Andromeda. Within the boundaries of Cassiopeia are the two dwarf elliptical galaxies NGC 185 and
NGC 147. They are completely unremarkable except for the fact that they are companion galaxies of the Andromeda Galaxy! In the sky, the Andromeda Galaxy lies quite a bit below these two galaxies.

    A very wide view showing an area that encompasses Cassiopeia as well as parts of neighbouring Cepheus. This area is extremely rich in Milky Way stars and many parts are dimmed by dark nebulae. Hover your mouse over each object to find out what it is and objects with a hand icon link to a closeup image.      
Image copyright T. Hallas
M52 is a striking cluster with a dense field of the Milky Way behind it adding to its lustre. It contains a large number of 200 stars with the many blue stars being complemented by a sparse number of yellowish stars.
M103 could be described as a northern version of the Jewel Box Cluster in Crux. It comes complete with a trio of stars at the very centre with a ferociously red star in the middle. This trio and the main surrounding stars in the central region seem to form the shape of a five pointed star. Stars forming the shape of a star is not something you would expect to see in a cluster.
Owl Cluster (NGC 457):
With its wings outstretched to greet you, the Owl Cluster is a high flying avian shaped cluster near Delta Cassiopeiae. While watching this cluster with a small telescope, you might feel that you are being watched by the two 'eyes' of the cluster. The brightest of these two stars is Phi Cassiopeiae, which is visible with the naked eye. Finding this star with a finderscope is a good method of locating this amazing open cluster. Some people see a little green man (E.T) instead of an owl.
NGC 663:
A cluster of 100 stars, the brightest form a diamond shape in the middle. Attached to the upper star of the cross is a circle of stars that are within the diamond.
NGC 663 makes a stunning pair with the nearby NGC 654 and both are in front of a large swath of the Milky Way.
NGC 7789:
If densely populated open clusters are your thing, then this one is the best in Cassiopeia. Observing it can reveal that it has a 'star' appeal and there are thousand members in total with 300 or 400 in the main central region. It is fairly ancient with dozens of old yellow giants.
Tombaugh 4:
In 1930 the historic discovery of Pluto was made by Clyde Tombaugh. In 2006 the historic decision to demote the planet was made by the IAU. Anyway this is a cluster that belongs to a catalogue of open clusters that was created by Clyde Tombaugh. It is small so a large telescope will be needed to see its 30 stars and a larger telescope would be needed to see the background haze of red nebulosity.
Bubble Nebula (NGC 7635):
The Bubble Nebula is a crystalline looking bubble ejected by a powerful Wolf Rayet star. It is covered in places by gaseous arcs and knots that are the result of material being more dense than the surrounding gas in the bubble. The whole wind blown nebula is imposed on a HII region known as Sh2-162, which can be seen in the image at the top of this page.
Pacman Nebula (NGC 281) and IC 1590:

Queens, kings and heroes have all been immortalized in the heavens but a video game 'character'? The Pacman Nebula's name is due mainly to a large elongated dark lane of dust that cuts the pink emission nebulosity into two opposing parts that seem to be connected by nebulosity on the left side although the whole nebula might be one round patch in reality. As well as one main dark lane, surrounding this is what appears like black ink splilt on the delicate petals of a flower. These are secondary dark patches that further add to the enduring appeal of this nebula.

On the left side of the nebula, glowing arcs and knots stitch the edges of the main complex. Near the middle are dark globules that appear to have an outer glow when observed closely. These are Bok globules and are stellar factories where stars are being manufactured.

Lighting up the ethereal pastel hues of NGC 281 is the star cluster IC 1590. The centre of this cluster contains a close knit group of stars that are responsible for the ionization of the gas that makes the nebula glow.

Heart Nebula (IC 1805) and Soul Nebula (IC 1848):

It could be said that these two giant emission nebulae are the heart and soul of Queen Cassiopeia. They are very active foundaries of star formation and they are physically linked together, the bridge can't be seen optically but radio telescope observations have detected it.

The Heart Nebula appropriately has a heartbeat in the form of the star cluster Melotte 15. The cluster is only 50 light years in front of the Heart Nebula and is part of the Cassiopeia OB association. OB associations are groups of an extremely luminous type of star that is classed at type 'O', just as there are different blood types.

On the upper left side of the Heart Nebula, the open cluster NGC 1027 sparkles innocuously. On the opposite upper right side are the nebulae IC 1795 and NGC 896 where recent star formation occured only 100 000 years ago.

The Soul Nebula looks like a baby when it is viewed sideways. Because of this, it is sometimes called the Embryo Nebula. Around the edges, there are bright rims of gas where more labourous star formation is occuring. The main nebula is lit up by the energy of two groups of OB stars. Near the upper left side is the separate patch of nebulosity IC 1871. Immediately to the left of the main complex is the tiny bipolar nebula, Sh2-201.

IC 59 and IC 63 :

Gamma Cassiopeiae is a shell star in the middle of the Cassiopeia's 'W' figure. It is losing its mass to a disk that encircles the star. Ultraviolet radiation from the star is evaporating two reflection nebulae that are to the left of the star.

They are arch shaped and they scatter the blue starlight they receive from the star. IC 63 is more purple and pink than blue because of an emission component and
IC 59 is more blue. Although it seems almost improbable, the difference between the appearance of both nebulae is due to them being at varying distances from Gamma Cassiopeiae, IC 59 is more distant. The evidence for this is a large nebulous shell around Gamma Cassiopeiae that was detected by the Wisconsin
H-alpha Mapper survey, both nebulae are part of this Ha shell.

Like an arcane secret sworn to secrecy, there is a tiny yellowish nebula between the two. It is very hard to spot even in large telescopes and is an unexpected find.

Claw shaped and enormous, this nebula is to the south of the Bubble Nebula. The brightest part is catalogued as Sh2-157a. The whole nebula acts as a 'border guard' as half is vertically in Cassiopeia and the other half is in Cepheus.

Confusingly appearing as a supernova remnant, this rosy red arc of gas is actually an uncommonly shaped planetary nebula. To add to the wonderful cavalcade of confusion, the few star atlases that plot this nebula use the icon for diffuse nebula instead of the planetary nebula symbol.

Sh2-188's chemical composition was studied carefully and this proved its true nature as it has elements that are found commonly in planetary nebulae.

IC 289:
Round and conventionally shaped, this planetary nebula consists of a bright purple part intertwining with a faint dark turquoise shell.
Sailboat Cluster (NGC 225):
Floating in the night sky between Gamma and Kappa Cassiopeiae, this boat shaped cluster is very bright at magnitude 7. It has a dispersed structure that is best seen in binoculars or small telescopes. The brightest stars form a mini version of Cassiopeia, which is like a constellation in a constellation.
The very first of the 158 nebulae that Sidney van den Bergh catalogued in the 1960's, this is a dazzlingly azure reflection nebula set in an irridescent field of stars. It is south of Cassiopeia's second brightest star, Caph (Beta Cassiopeiae) at the edge of a strange supernova remnant. Another unique feature of the area around it is a curious white oval cocoon shaped cloud. Adding to its mystique is an area empty of gas making it look like a squashed yin yang symbol! This could either be a bizarre coincidence or an illusion constructed by the mind.
Also found near Caph is this incredibly dim emission nebula that will test the skills of advanced observers. It is fairly round and a small detachment towards the south is the brightest part. Contrastingly, dark patches blot the northern portion and these are probably more challenging to glimpse than the main part.
Sh2-188   Open cluster NGC 663  
Looking like a mini version of
NGC 3199 in Carina, Sh2-188 has a prominent bow shock.
One of the many clusters found in Cassiopeia is NGC 663. It lies in a rich portion of the Milky Way.
Image copyright K. Crawford Image copyright B. Hubl
M52 in Cassiopeia [closeup by Rob Gendler] NGC 7538 in Cepheus [closeup by Adam Block] Sh2-161 in Cassiopeia Bubble Nebula in Cassiopeia [closeup by Johannes Schedler] NGC 7510 in Cepheus IC 1470 in Cepheus [closeup by Günter Kerschhuber] Sh2-157 in Cassiopeia [closeup by Chuck Vaughn] Open cluster King 19 in Cepheus Open cluster Czernik 43 in Cassiopeia Sh2-159 in Cassiopeia