1. The Universe: Galaxies, Stars, and Nebulae March 3, 2011

2. The Universe All physical matter and energy that exist in space: All physical matter and energy that exist in space: Planets Planets Stars Stars Galaxies Galaxies All the contents of intergalatic space All the contents of intergalatic space

3. A Planet Most scientist agree that a planet: Most scientist agree that a planet: Orbits a star – such as the Sun Orbits a star – such as the Sun Is round - due to the strength of its own gravitational pull Is round - due to the strength of its own gravitational pull

4. Galaxies NOT single stars – includes: Stars, Gas, and Dust NOT single stars – includes: Stars, Gas, and Dust Variety of shapes, sizes, and colors Variety of shapes, sizes, and colors Clustered in Groups Clustered in Groups Gravitationally attracted/held together Gravitationally attracted/held together

5. Galaxies Milky Way = part of Local Group Milky Way = part of Local Group 5 million light years across 5 million light years across In 1999 HST (Hubble Space Telescope) est. 125 billion galaxies; HST found 3,000 visible galaxies in space In 1999 HST (Hubble Space Telescope) est. 125 billion galaxies; HST found 3,000 visible galaxies in space

6. Galaxies Spiral = Milky Way Stars form “arms”, curve out from center, disk or pancake shaped Stars form “arms”, curve out from center, disk or pancake shaped Holds old & young stars, gas, & dust Holds old & young stars, gas, & dust http://www.hdwallpapers.com/photo/Space_pictures/Spiral_Galaxy_M81

7. Galaxies Elliptical Stars form shape like a football Stars form shape like a football http://www.astronet.ru/db/xware/msg/1226180

8. Galaxies Irregular No special shape = blobs w/threads No special shape = blobs w/threads Holds large amount of gas and dust Holds large amount of gas and dust http://apod.nasa.gov/apod/ap081229.html

9. Stars Large ball of gas that creates & emits its own radiation Variety of shapes, sizes, and colors Variety of shapes, sizes, and colors Nebula, Main Sequence, Red & Super Giants, White Dwarf, Brown Dwarf, & Supernova Nebula, Main Sequence, Red & Super Giants, White Dwarf, Brown Dwarf, & Supernova UM = M agnitude = degree of brightness UM = M agnitude = degree of brightness Lifecycle – NO star lives forever Born, Matures, Grows old, & Dies

11. Nebula – dense region inside begins to shrink, warm up, becomes a protostar http://www.calvin.edu/academic/phys/observatory/images/Astr110.Fall2006/deLa nge.html A Star is born Protostar – critical temperature is reached – hydrogen begins fusing into helium Protostar – critical temperature is reached – hydrogen begins fusing into helium http://photojournal.jpl.nasa.gov/

12. Once a star is born it becomes a Main Sequence Star – shines as nuclear reactions inside produce light and heat Main Sequence Star – shines as nuclear reactions inside produce light and heat But if it doesn’t have enough mass to produce radiant heat it becomes a Brown Dwarf But if it doesn’t have enough mass to produce radiant heat it becomes a Brown Dwarf http://www.for68.com/new/2005/12/su86402129331912150024200-0.htm http://dsc.discovery.com/news/2009/04/20/brown-dwarf-cool.html

13. At this point Stars can become a Super Giant or Red Giant Super Giant Star of greater mass Expands, cools, & turns red Star of greater mass Expands, cools, & turns red Super Giant EXPLODES blasting away outer layers becoming a Super Nova http://apod.nasa.gov/apod/ap001222.htmlhttp://news.discovery.com/space/beautiful-supernova-violence.html

14. Supernova can become either: Neutron Star – core collapses & becomes very dense Black Hole – core collapses completely & vanishes http://www.science.psu.edu/news-and-events/2007-news/Fox8-2007.htmhttp://www.nasa.gov/mission_pages/chandra/multimedia/photo09-078.html

15. If a Star becomes a Red Giant, then Red Giant – star of less mass expands, glows red as it cools, then Planetary Nebula – outer layer of gas puff off; hot core will be white dwarf http://smithsonianscience.org/2010/03/archaeological-%E2%80%9Cdig%E2%80%9D-in-outer- space-uncovers-an-ancient-star/ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html

16. Red Giant =Planetary Nebula = White Dwarf = White Dwarf Cooling White Dwarf – very dense, almost transparent White Dwarf Cooling – takes billions of years to cool then fades to black http://www.jpl.nasa.gov/news/features.cfm?feature=576http://imagine.gsfc.nasa.gov/docs/science/know_l1/dwarfs.html

17. Cooling White Dwarf = Black Dwarf Black Dwarf - A non-radiating ball of gas; star stops glowing http://news.discovery.com/space/intermediate-black-hole-implicated-in-stars-death.html