Other Components of the UniverseSection 9.6

Star Clusters

• A group of stars held together by gravity• Open star clusters – collections of 6 to 1000s

of younger stars• Globular clusters – ball shaped collection of

1000s to 1000000s of very old stars

Galaxies• Collections of millions/billions of stars, planets, gas

and dust measuring up to 100 000 ly across.• Come in different shapes/sizes– Elliptical – spherical to flat oval shape– Spiral – spinning pinwheels– Lenticular – central bulge surrounded by flattened disc– Irregular – no definite shape

The Milky Way• 2 spiral arms, central bulge of old stars, disc of

newer stars around the bulge• Our solar system is located on the inner edge of one

of the spiral arms (26 000 ly from the inner core).• There is a supermassive black hole at the center

Quasars – Powerhouse of Energy

• They are distant, young galaxies that emit large amounts of energy produced by a supermassive black hole at its centre.

• The central region is more luminous than normal – they look like stars though a telescope

Today’s Tasks

• Pg. 387 Classifying Galaxies– Complete #1, A-E (yes…E will be homework)

• Pg. 391 #1, 6, 8