Lunar Phases

Size Largest stars = supergiants or giants The next step down in size are called medium stars. White dwarf stars are about the size of Earth THE SUN IS A MEDIUM STAR

Temperature The color of the star depends on temperature Red stars = cool stars Yellow stars = medium stars (the sun!) White = hot stars Blue = hottest of all stars

Brightness Brightness is the amount of light given off. Brightness depends on distance from Earth and actual brightness. Brightness is measured in 2 ways: absolute magnitude which is difficult (math!! Ahhh!!!) apparent magnitude which is easier (just look at it)

How did stars get there?

Star Birth Stars begin as nebula (gas and dust) Gravity acts on it – becomes protostar Nuclear fusion begins – a star is “born.”

Lifetime Earning Your Place in the Galaxy How long a star will last depends on its mass. Big stars with large mass, will burn up faster and have a short life. Stars with small mass have a long life because they do not burn up as fast.

Death :*( Average size stars lose layers (like a onion) and become white dwarf stars. Once fusion stops they are black dwarfs. Super massive stars explode into supernovae. Then they become a neutron star or black hole.

HR Diagram

There’s more out there than our Milky Way (mmm….candy)

Spiral Look like a pinwheel that rotates Lots of dust, therefore new stars Milky Way = our galaxy, a spiral galaxy

Elliptical Flat and oval shaped Very little gas and dust. Old stars.

Irregular Every other galaxy that’s not spiral or elliptical. No specific shape.

EM Spectrum EM Waves all travel at the speed of light Light is an EM wave. Gamma rays = super high energy Radio waves = super low energy