Light Years =distance = the speed of light =300,000 km/s =the further you look into the distance, the further back in time you are looking = how far light travels in one year

Life Cycle of a Star Stars appear to be different because of 1.Mass –how big it is 2. Stage of their life cycle –where it is in its life 1.Luminosity –how it shines 2.Surface temperature –how hot its surface is

Mass –measured on a balance -how much stuff is there not how much it weighs. Gravity causes weight

Stages of stars are mapped out based on if they are a High mass or Low mass star Low Mass Star Stage 1 –nebula = cloud made out of star forming materials like dust and gas (gravity begins to contract the material) Stage 2 –Protostar large mass of Hydrogen, high temp and contraction continues (not quite a star) (high temp causes contraction to stop and fusion to begin) (fusion is when two atoms are pushed together to form one)

Stage 3 –Star = undergoes fusion Hydrogen to Helium (orange, yellow, red) When Hydrogen is gone = gravity releases outer shell, star swells (the Hydrogen shell around the Helium core explains red swelling) Stage 4 –Red Giant = shell shrinks and Helium fusion begins Stage 5 –White Dwarf = small, hot, and dim

High Mass Star Stage 1 –nebula = fusion much faster because a large mass burns faster (fusion of the Hydrogen to Helium eventually turns it to iron) Stage 2 –Protostar = same as Low mass star Stage 3 –Red SuperGiant = similar to Low mass star

Stage 4 -Super nova –energy is released when the outer layer and elements are blown away Stage 5 -Newtron star –ball of neutrons left behind or -Blackhole –super dense remnants

Luminosity Total amount of power the Hydrogen radiates into space Amount of light that reaches us Sun looks bright because it is so close As materials get hotter, they emit more light, so as they cool, they emit less light

Spectral Class O –blue/hot B –blue-white/less hot A –white F –yellowish-white G –yellow K –orange M – red –low energy/low temperature

Hertzsprung-Russell Diagram Important tool for how stars change over time Luminosity Spectral temperature

Tools to study the Universe Telescopes –cause objects to appear larger Optical telescope –uses visible light only

Reflecting telescope

Refracting telescope

Radio telescope Curved radio waves –we can’t see them Frequency too low for our vision to see

Observatories Audio light pollution

Satellites In space Detect parts of electromagnetic spectrum (x-rays, gamma rays, radio waves)

Space Shuttles and Rockets Dansl'espace.wmv Dansl'espace.wmv To travel into space

Questions What is the best piece of equipment that you could use to observe stars in space? What does luminosity mean? What diagram refers to colors and temperature when we observe stars? What kind of telescope shows objects right-side-up? Which stages of a star’s life are represented in both large and small mass stars?