What characteristics do all galaxies share? What makes them different?

1 Answer
Feb 3, 2016

All galaxies contain groups of stars and other material held together by gravity.


Galaxies can contain anywhere between a few thousand and #100# trillion (#10^14#) stars.

Some galaxies (like our own Milky Way galaxy) have central black holes and some don't.

Galaxies can take a variety of shapes, e.g. spiral, barred-spiral, elliptical or irregular.

Galaxies differ in the range of ages and types of stars.