Galaxies are the homes of billions of stars and solar systems, which are held together by gravity. Galaxies come in many different shapes and sizes. The galaxy that our sun resides in is known as the Milky Way due to the bright white cloud that appears to span across our sky at night. Galaxies, like solar systems, tend to be flat and disc shaped although there are variations to this. The Milky Way is a spiral galaxy with our solar system position near the outer rim of the disc. As we look out into the deep regions of the universe, we look edge on through the disc and this is why there appears to be so many stars through the elliptic.
The most common shape of a galaxy is the swarf elliptical and irregular galaxy with the spiral galaxy being the largest group. There are other shapes such as barred spiral, elliptical and clustered galaxies. These systems vary from 15,000 to 150,000 light years in diameter and contain several hundred billion stars. Not all galaxies are lined up on the same plane as our galaxy and therefore can be observed; edge on, from above or face on and at various angles. A spiral galaxy such as M100 is face on allowing the spiralling arms to be clearly seen where a similar galaxy that is edge on will look like a fussy ball and a dark streak through the middle as seen with NGC 5128 known as Centaurus A.
A barred galaxy like NGC136 5 and M95 are spiral galaxies that exhibit a thin line through the middle of a glowing nucleus. This bar or line separates the galaxy and is most likely caused by outlying dust and ice absorbing or reflecting the light behind it. Elliptical galaxies are discs or clusters of stars that are old and dying. Similarly Lenticular galaxies have a central nucleus but no spiral structure. Both these and eliptical galaxies are very old galaxies.