1. Formation of the Solar System and The Universe

2. Our Solar System Sun is the center of a huge rotating system of: Sun is the center of a huge rotating system of: –Planets –Their satellites –Smaller bodies Most of the mass of solar system is the sun (99.85%) Most of the mass of solar system is the sun (99.85%)

3. Our Solar System Planets move in elliptical orbit Planets move in elliptical orbit –All in same direction Terrestrial planets = small and rocky Terrestrial planets = small and rocky –Mercury, Venus, Earth, Mars Jovian planets = huge gas giants Jovian planets = huge gas giants –Jupiter, Saturn, Uranus, Neptune

4. Formation of the Solar System Between stars = gas and dust Between stars = gas and dust –Nebula = cloud of gas and dust Hydrogen, helium, heavier elements Hydrogen, helium, heavier elements Nebula begin rotating slowly and contract because of gravity Nebula begin rotating slowly and contract because of gravity –Clouds contract --> spin faster

5. Nebular Theory Nebular theory states that the sun and all bodies in the solar system formed from a rotating disk of interstellar gas and dust. Nebular theory states that the sun and all bodies in the solar system formed from a rotating disk of interstellar gas and dust. –4.6 billion years ago This cloud is roughly spherical and so dense that it begins to collapse under its own gravity This cloud is roughly spherical and so dense that it begins to collapse under its own gravity

6. Nebular Theory As the speed of rotation increased, the center of the disk flattened. As the speed of rotation increased, the center of the disk flattened. The dense center formed the sun and planets formed along the flattened, nebular cloud The dense center formed the sun and planets formed along the flattened, nebular cloud Nebular theory Nebular theory Nebular theory Nebular theory

7. How the Solar System Formed

8. Planetesimals Planetesimals = small, irregularly shaped bodies Planetesimals = small, irregularly shaped bodies –Solid bits of matter collided and clumped together = accretion –Planetesimals grew larger –Enough mass --> exert a gravitational pull on other objects –Grew into planets

9. Birth of Planets Inner solar system = close to sun Inner solar system = close to sun –Temperatures high Only metals and silicate minerals Only metals and silicate minerals Too hot for ices of water, carbon dioxide Too hot for ices of water, carbon dioxide Outer solar system = cold enough for ices of water Outer solar system = cold enough for ices of water –Accumulations of solid bits of material and large quantities of ices –Large enough to capture gases (hydrogen and helium) --> grew into giants

10. Galaxies Galaxies = groups of stars, dust, and gases held together by gravity Galaxies = groups of stars, dust, and gases held together by gravity Our galaxy = Milky Way Our galaxy = Milky Way –More than 100 billion stars in Milky Way –Looks milky because the solar system is located within a flat disk We view it from inside and see stars in every direction We view it from inside and see stars in every direction

11. The Milky Way Galaxy Interstellar matter blocks our vision Interstellar matter blocks our vision –Radio telescopes Size = large spiral galaxy Size = large spiral galaxy –Disk = 100,000 light-years wide –Nucleus = 10,000 light-years thick Milky Way = taken by a camera mounted on a satellite

12. The Milky Way Galaxy Structure Structure –At least 3 spiral arms –Sun is in one of these arms about 2/3 of the way from the center –Stars in arms rotate around the nucleus –Outermost arms move slowest

13. Types of Galaxies Spiral Galaxies Spiral Galaxies Elliptical Galaxies Elliptical Galaxies Irregular Galaxies Irregular Galaxies

14. Spiral Galaxies Disk-shaped Disk-shaped –Greater concentration of stars near center –Arms extend from nucleus –Both young and old stars Youngest in arms Youngest in arms –20% of all galaxies Barred spiral = stars arranged in shape of bar Barred spiral = stars arranged in shape of bar –Milky Way? –10% of al galaxies

15. Elliptical Galaxies Round to oval Round to oval Most are small Most are small No spiral arms No spiral arms Contain old stars Contain old stars 60% of all galaxies 60% of all galaxies

16. Irregular Galaxies Irregular shapes Irregular shapes Made up of mostly young stars Made up of mostly young stars 10% of all galaxies 10% of all galaxies

17. Galaxy Clusters Galaxies grouped in clusters Galaxies grouped in clusters –May contain thousands of galaxies Our cluster contains 28 + galaxies Our cluster contains 28 + galaxies Galaxy clusters make up superclusters Galaxy clusters make up superclusters

18. The Expanding Universe Doppler Effect = perceived change of wavelength of a wave that is emitted from a source that is moving away or toward an object Doppler Effect = perceived change of wavelength of a wave that is emitted from a source that is moving away or toward an object –Takes time for the wave to be emitted nearer to you than the end Listener’s perspective = wave appears to be stretched Listener’s perspective = wave appears to be stretched Opposite for wave moving toward you Opposite for wave moving toward you

19. The Doppler Effect Light from a source moving away from you appears redder Light from a source moving away from you appears redder –Waves are lengthened Moving toward you appears bluer Moving toward you appears bluer –Waves are shortened

20. How are Doppler shifts measured? From dark lines in spectrum From dark lines in spectrum –Comparing them with standard spectrum –We’ll talk about this more in depth when we discuss stars

21. Doppler Effect in Astronomy Determines whether a body in space is moving way from or toward Earth Determines whether a body in space is moving way from or toward Earth –Large Doppler shifts = higher speeds –Small Doppler shifts = slower speeds

22. Red Shift Most galaxies have Doppler shifts toward red end of spectrum Most galaxies have Doppler shifts toward red end of spectrum –Earth and source are moving away from each other

23. Hubble’s Law Greater red shifts = faster speeds Greater red shifts = faster speeds Hubble’s Law = more distant galaxies have greater red shifts --> they must be moving away from us at a speed that is proportional to their distance Hubble’s Law = more distant galaxies have greater red shifts --> they must be moving away from us at a speed that is proportional to their distance Red shifts of distant galaxies tell us that the universe is expanding Red shifts of distant galaxies tell us that the universe is expanding

24. The Big Bang Remember…all galaxies are moving away from us Remember…all galaxies are moving away from us –We are not at the center of the universe Big Bang = the universe began as a violent explosion from which the universe continues to expand, evolve, and cool Big Bang = the universe began as a violent explosion from which the universe continues to expand, evolve, and cool –Universe was a dense, hot, supermassive ball 13.7 billion years ago --> violent explosion --> material hurled in all directions 13.7 billion years ago --> violent explosion --> material hurled in all directions –All matter and space created –Atoms formed –Gases cooled and condensed --> formed the stars

25. The Big Bang

26. Evidence for the Big Bang Red shift of galaxies Red shift of galaxies –Universe is still expanding Cosmic background radiation = energy Cosmic background radiation = energy –Coming from every direction in space –Produced during big bang

27. How will the universe end? Will it last forever? Will it last forever? –Stars slowly burn out –Invisible matter, black holes, dark and cold universe The Big Crunch? The Big Crunch? –Galaxies stop moving away –Combine into high-density, high-energy mass –Fiery death

28. Citations Spin Around the Solar System, A: How the Solar System Works. United Learning. 2001. Spin Around the Solar System, A: How the Solar System Works. United Learning. 2001.unitedstreaming. Stargazing: How the Sky Works. United Learning. 2002. Stargazing: How the Sky Works. United Learning. 2002.unitedstreaming. What's Out There? Our Solar System and Beyond. Rainbow Educational Media. 1997. What's Out There? Our Solar System and Beyond. Rainbow Educational Media. 1997. Waves: Energy in Motion. AIMS Multimedia. 1996. Waves: Energy in Motion. AIMS Multimedia. 1996.unitedstreaming. Deep Space: The Universe and Its Future. AIMS Multimedia. 2004. Deep Space: The Universe and Its Future. AIMS Multimedia. 2004. unitedstreaming. unitedstreaming.