Interactive Astronomy

They are disk-shaped galaxies that have swirling arms from the middle of the galaxy, like that of the Milky Way.

They are spiral galaxies whose arms come from a large cluster of stars in the Central Bulge. The large cluster of stars in the middle are known as the Bar and are shaped like a rugby ball.

They are flat disks like all spiral galaxies but do not have arms.

They are ball shaped galaxies which are spherical in shape. They mostly consist of old about-to-burn-out stars and globular clusters, although a minority of them actually houses extremely young stars. The astonishing fact about Elliptical galaxies is that no new stars are being produced. The best theory so far is that elliptical galaxies are formed when two or more galaxies collide and merge, and the impact force compresses and forms very young stars. The elliptical galaxy then uses up all of its gas needed to form stars. The theory gets more supporting evidence from signs of colliding galaxies today which had helped shape certain unique galaxies.

These galaxies are simply galaxies with no regular shapes grouped as one. New stars form all the time and Irregular galaxies are usually smaller than spirals. Irregular galaxies have plenty of gases which can form stars (interstellar gases).

Dwarf galaxies just mean smaller galaxies. They consist of spiral, elliptical and irregular ones and as long as they are small, they are in.