1. Stars, Galaxies, and the Universe

2. The Life Cycle of Stars First Stage
ball of dust and gas pulled together by gravity
nuclear fusion begins when star becomes denser (changing hydrogen to helium)

3. Main-Sequence Stars
Giants and Supergiants
2nd stage
longest stage
creating energy through nuclear fusion
3rd stage
red giant = large, reddish star late in life cycle
expands and cools once hydrogen is all used up

4. White dwarfs
Final stage
small, hot dim star that is the leftover center of an old star

6. Supernova
Neutron Star
gigantic explosion
massive star collapses and throws outer layers into space
follows a supernova
star that has collapsed under gravity to the point where all of the star’s particles are neutrons

7. Pulsar
Black Hole
spinning neutron star
object so massive and dense even light cannot escape its gravity
happens when center of collapsed star has a very high mass

8. Top – smaller star, like our sun
Bottom - large star, like Betelgeuse

9. Galaxies

10. Formation of the Universe
Cosmology
Galaxy
Movement
study of origin, structure, and future of the universe
scientists study movement of galaxies
measurements show galaxies are moving apart
Raisin Bread Model  As the universe expands, galaxies move further apart

11. Big Bang Theory
universe began with a tremendous explosion about 13.7 billion years ago
Radiation found coming from all direction in space left over from big bang

12. Structure of Universe
Age of Universe
every object is part of a
larger system
Ages of stars help calculate
the age of the universe
universe is at least as old as
oldest star
Distance between Earth and
other galaxies rate expansion

13. A Forever Expanding Universe
scientists predict if there was enough matter, gravity could eventually stop expansion and it would collapse to original state
they do not believe there is enough, so they think it will expand forever (even after stars die and it becomes cold and dark)