The vast majority of the stars discovered are part of huge
systems called galaxies. Millions or billions of stars - tiny
red dwarfs, sunlike stars, supergiants, neutron stars, nebulae,
clusters and many other kinds of stellar objects - are bond
together in a massive gravitational system that spans across
eons and eons of space, sometimes more than 100 000 light years.
In 1924 Edwin Hubble measured the distance to the Andromeda
galaxy. He found that it was about hundred thousand times more
distant than the nearest stars, hence he concluded that it was a
separate galaxy, like our own galaxy, the Milky Way. Edwin
Hubble changed our view of the universe. Later on he made a
system that classified the galaxies depending on their shapes.
This system is used even today by astronomers. There are many
kinds of galaxies: some are elliptic, others are formed like a
spiral, and yet other have these irregular shapes. Irregular
galaxies usually originally fit within Hubble's galaxy
classification, but they get their shapes