1 / 22

Our Universe Structure

Our Universe Structure. Smallest to largest: Planets  Stars /Solar systems GalaxiesGalaxy ClustersUniverse Universe contains hundreds of billions of galaxies. Galaxies contain hundreds of billions of stars. Imagine the possibility of finding life. Life on other planets IS possible!

chi
Télécharger la présentation

Our Universe Structure

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Our Universe Structure • Smallest to largest: • PlanetsStars/Solar systemsGalaxiesGalaxyClustersUniverse • Universe contains hundreds of billions of galaxies. • Galaxies contain hundreds of billions of stars. • Imagine the possibility of finding life. • Life on other planets IS possible! • If only one planet in each galaxy had life. . . • Now imagine the probability of finding it! • 1.0 X 1022!

  2. Distance - factors • Distance indicators = objects whose diameter or absolute magnitude is KNOWN • Look-back time = looking at galaxies millions of light-years away = looking at light that left galaxy millions of years ago, like looking back in time.

  3. Distances • Astronomical Unit = distance between Earth and Sun, 93 million mi. (solar system) • Recall: Light Year = distance light travels in one year, 9.46 X1015 m (near by stars) • Parsec = 3.08 X 1016 m = 3.26 light years (stars within our galaxy) • Megaparsec = 1 Mpc = 3.26 million light years (galaxy clusters & galaxies)

  4. Types of Galaxies • Spiral • Elliptical • Irregular

  5. Spiral Galaxies • Usually disk shaped with a greater concentration of stars in the center. • Arms sweep outward. • 20% of all galaxies - From nucleus • 10% of all galaxies - From a rigid bar • Tend to spin faster in the center. • Contain both young and old stars • Has both gas and dust to make new stars!

  6. Milky Way Galaxy • Spiral galaxy example • 100,000 L.Y. across • 10,000 L.Y. thick at the nucleus • Three spiral arms (splintered) • Our solar system is 2/3 way down one arm (30,000 L.Y. away from nucleus) • Spherical halo/bubble made of gas and globular clusters.

  7. Milky Way Edge View

  8. Artist Milky Way Galaxy

  9. Artist Milky Way Galaxy

  10. Elliptical Galaxies • Range of shapes- round to oval • Depends on our frame of reference! • Depends on eccentricity. • Most are small, but the largest galaxies known are elliptical • 200,000 L.Y. diameter • 60% of all galaxies • No arms or bars • No visible gas or dust-which means no NEW stars are forming. • Composed of old stars • Lack hot, bright stars • Stars concentrated near center.

  11. Elliptical Galaxy NGC 4881

  12. Irregular Galaxies • Make up 10% of known galaxies • Composed of young and old stars • Clouds of gas and dust w/o nucleus or arms • Huge! Can see 2 with your eye alone • Large and Small Magellanic Clouds • Named after Magellan who discovered them in 1520. • 150,000 L.Y. away, nearest neighbors

  13. Large Magellanic Cloud

  14. Small Magellanic Cloud

  15. eaRTH SPACe science All galaxy types represented. Make your own at: http://mygalaxies.co.uk

  16. Galaxy Clusters • Group of stars is a galaxy • Galaxies are also grouped into clusters • May contain thousands of galaxies • Our cluster is called the Local Group • Has at least 28 galaxies • Galaxy clusters can be grouped into superclusters • Believed to be the largest grouping in the universe.

  17. Collisions • May dominate galaxy evolution • Galaxies collide, stars don’t • Galaxies are much closer together than stars • Causes rapid star formation and one may “steal” gas/dust from the other. • Galactic cannibalism • Milky way vs. Large & Small Magellanic clouds • Evidence in distortions and computer models • Last a hundred million years

  18. Galactic Cannabilism Image of Lg. Magellenic cloud. Dots are stars stolen from Sm. Mag. Cloud. Proof = opposite rotation, odd orbits, and different composition of LMC. (rotation, orbit, & composition similar to SMC)

  19. Cartwheel Galaxy

  20. Hubble’s Law • Edwin Hubble, 1929 • Realized that dimmer galaxies are likely farther away. • The farther the galaxy, the greater the red shift. • Red shift = when a light source is moving away from the observer, the light waves get “stretched” causing it to appear redder than it really is. • Hubble’s law - the farther the galaxy is from us, the faster it is moving away. • Vr=Hd, H = Hubble’s constant, value still being determined (70-100 km/sec/Mpc)

  21. Red Shift • Top = Red shift: object moving away • Middle = No shift: object not moving toward or away • Bottom = Blue shift: object moving toward • Example: Sounds/Doppler Effect

More Related