1. Astronomy Origin and Fate of the Universe

2. Hubble’s Law Hubble’s law basically says that the universe is expanding. That is to say that the space between galaxies is increasing; with greater distance is greater speed. Closer galaxies are moving apart slower than those galaxies farther away. HOW DO WE KNOW?

3. Hubble’s Evidence = Spectra Spectra Spectra are the colors produced when the wavelengths of light are separated.

6. The Doppler Effect The Doppler effect is a change of light or sound wavelengths as a source moves t tt toward or a aa away from the observer. Red shift = source is moving a aa away so wavelengths stretch into longer wavelengths Blue shift = source is moving c cc closer so wavelengths squeeze into shorter wavelenghts. B LUE TO YOU.

9. Deep Space Phenomena Based on the observed rates of expansion it is believed that about 15-20 billion years ago all matter was concentrated into one “primeval atom”. BIG BANG This “atom” exploded and sent all matter and space expanding = BIG BANG

10. What are Stars? Star = a hot, glowing sphere of gas that produces energy by fusion (of hydrogen molecules). –Some stars produce more energy therefore they are hotter.

11. How Do Stars Form? NebulaNebula = a cloud of dust and gas where stars are born. nuclear fusion –Here gravity pulls particles together and nuclear fusion starts at 10,000,000 o C and a star is born.

12. The Horse Head Nebula

13. More Horse Head Nebula Shots

15. Types of Stars Depending on the conditions within a nebula, different types of stars can form: Red Giants = big, “cool” stars White Dwarfs = “small”, hot stars

16. How Are Stars Classified? Stars are classified by: –Temperature –Color –Luminosity / Brightness

17. Stars are Classified by Temperature and Color. HOTCOLD BLUEWHITEYELLOWORANGEREDBROWN

18. What is a Main Sequence Star?

19. What is a Main Sequence Star? The H-R diagram represents a pattern that was discovered that allows stars to be compared by brightness and color. The majority of stars are found in a band stretching diagonally across the diagram called the “Main Sequence”. Stars start out in the M MM Main Sequence and as the core cools, they move onto the giant category. A few rare stars are bigger and brighter and become s ss supergiants.

20. Stars are Classified by Brightness Actual brightness is how bright a star really is. Actual brightness does not change, it is an absolute value. Example: a 40 watt light bulb is actually converting 40 watts of energy into light. Apparent brightness is how bright a star looks from earth. Apparent brightness changes depending on distance from earth and viewing conditions (atmosphere). Example: a 40 watt light bulb 10 feet away appears brighter than a 40 watt bulb 100 feet away.

21. …And After Stars are Born?

22. Life Cycle of a Star

24. Neutron Stars neutron star A neutron star results when a white dwarf collapses and the pressure converts the electrons into atomic nuclei to produce neutrons. neutron star supernova The outer portion of a neutron star may explode with incredible force producing a supernova.

25. Supernova What is a Supernova? Supernova is when the core of a star collapses and the outer portion explodes. This is the “death of a star”. What remains when a star dies out depends on the mass of the star. –M–Material from the explosion may form a new star called a p pp pulsar – a rapidly spinning neutron star. –T–The most massive stars collapse into black holes.

27. What is a Black Hole? Black Hole = the most dense thing known to exist in the universe. The gravity of a black hole is so great that even light can not escape the pull of a black hole.

28. The massive density of Black Holes creates a gravitational force that pulls in anything that comes within reach: the reach of this force is called the event horizon.

30. The fate of objects that enter a Black Hole is still uncertain. ?