1. Nebular Hypothesis Theory Cornell Notes Page 41-42

2. What is a Theory? A theory is both a goal and a tool of research Theories ask the questions that look beyond the facts and laws of science Theory statements can be refuted, but not verified, no matter how strongly we believe in the truth of a theory. It is always possible for it to be falsified.

3. Nebular Hypothesis Theory The birthplace of our solar system was a NEBULA –A nebula is a “fuzzy” patch in the sky, either light or dark; a cloud of gas and dust –Our solar system evolved from a swirling cloud of dust (Nebular Theory) –Gravity caused the gases and dust to be drawn together into a denser cloud (rate of rotation increased)

4. Nebular Hypothesis Theory cont. –As a result the cloud collapsed to resemble a disk. Most of the mass collapsed in the center –Matter in the rest of the disk clumped together to form planetesimals = protoplanetary bodies –Hydrogen gas combined or fused to form helium atoms (nuclear fusion – a source of energy from the sun!) The Sun was born!!!

5. Examples of Nebulas Eagle Nebula

6. Examples of Nebulas Orion Nebula –Located in the constellation Orion

7. One last example Cats Eye Nebula

8. Our solar system Terrestrial planets: inner part of solar system Characteristics: small and rocky –Mercury –Venus –Earth –Mars

9. Our solar system Gas giants: larger planets Characteristics: colder and covered with Hydrogen (gas & liquid) –Jupiter –Saturn –Uranus –Neptune Pluto: no longer considered a planet but still there!!!

10. Planets (continued) Rotation is how long it takes for a point on planet to spin around and face the sun –Length of day Revolution is how long it takes a planet to go around the Sun; also known as orbit –Length of year

11. Other stuff in the solar system CometsAsteroidsMeteoroidsGasDustSatellites Space “Junk” Can you think of anything else?

12. Planets (con’t) Comets – Halley’s Comet – 76 yrs 2052 –Mixtures of frozen gases, ice and rocky debris –Outer solar system –Looping orbits bring close to the Sun, ice melts thus having streaming tailsAsteroids –Dark, rocky bodies that orbit the Sun

13. Milky Way Galaxy Swath of light formed by the glow of billions of stars Flat spiral collection of stars Largest celestial feature Formed 10 billion years ago

14. Other Galaxies Whirlpool GalaxyAndromeda Galaxy Sombrero Galaxy Large Magellanic Cloud

15. Halley’s Comet - http://science.discovery.com/videos/100- greatest-discoveries-shorts-halleys- comet.html http://science.discovery.com/videos/100- greatest-discoveries-shorts-halleys- comet.html http://science.discovery.com/videos/100- greatest-discoveries-shorts-halleys- comet.html Space Junk - http://www.natural- environment.com/images/blog/space_junk _2.jpg http://www.natural- environment.com/images/blog/space_junk _2.jpghttp://www.natural- environment.com/images/blog/space_junk _2.jpg