The Hertzsprung – Russell Diagram

Astronomers use the H-R diagram to…* Show what stars are made of by looking at their color.

*Compare the colors, brightness, temperature, and mass of stars.

The Hertzsprung – Russell Diagram

*Look at the two stars, Sun and Zeta Eridani. Compare the two stars based on color, surface temp., and magnitude (brightness).

Sun is yellow– Zeta Eridani is Blue. Color is due to a stars temperature. Sun temp. is much lower(6,000 K) – Zeta Eridani temp. is much higher(40,000 K)

Sun is average magnitude – Zeta Eridani is very high magnitude.Sun and Zeta Eridani are Main Sequence stars. Incresed temp. = Increased Magnitude

Characteristics of a Galaxy

A Galaxy is a large group of stars, gas, and

dust held tighter by

gravity.

Types of Galaxies

Spiral Galaxy*Have spiral areas that

wind outward from inner regions.

*The arms are made up of stars and dust.

*Milky Way (our universe is a spiral).

*Brightest stars.*Most common galaxy.

Types of Galaxies

Elliptical Galaxy*Shaped like large

three –dimensional ellipses.

*Oldest stars.

Types of Galaxies

Irregular Galaxy*Have many shapes*Smaller than other

types of galaxies.*Newest stars.

Universe from Largest to Smallest

Universe Galaxy Solar System Planet