Colors of Galaxies
A galaxy’s color is due to the combined color of its stars.
A galaxy’s color also tells us whether star formation
occurred recently, within that galaxy. A galaxy with lots
of recent star formation has many young, blue stars
Ways of Measuring the Size of Galaxies
The number of stars contained in a galaxy can range from less than a million
stars, in dwarf ellipticals, to several trillion stars, in giant ellipticals. Galaxies can
be several thousand to hundreds of thousands of light-years across.