Galaxies and the Universe: Galaxies and the Universe


Objectives: Objectives Identify the Earth’s place in the Milky Way galaxy Describe our concept of the milky way galaxy. Compare the different types of galaxies Explain the clustering of stars and galaxies in the universe Explain the usefulness of making observations of the universe different wavelengths.


Galaxy: Galaxy A galaxy is a cluster of 100-200 billion stars It is currently being shown that most galaxies have a massive blackhole at their center (including ours) All stars rotate around the central blackhole. Infrared image of the Andromeda galaxy taken by the Spitzer space telescope


Milky way galaxy: Milky way galaxy The Galaxy is about 80-100 thousand light years in diameter It orbits the center of the universe It contains more than 200 billion stars orbiting its center Our solar system is located on a outer arm of the spiral http://upload.wikimedia.org/wikipedia/en/0/09/Milky_Way_2005.jpg Photograph of milky way from the Lund Observatory


Three types of galaxies: Three types of galaxies Spiral- nuclei of stars in the center with arms that radiate outward Elliptical- have little or no measurable gas or dust and are composed completely of stars. They have no disks at the center and appear oblong in shape. Irregular- small and faint with unevenly spread stars M32 elliptical galaxy- taken at the Lowell Observatory


The Universe- Clusters of galaxies: The Universe- Clusters of galaxies Galaxies are clusters of billions of stars Galaxies are arranged in clusters and superclusters There appears to be huge clusters of galaxies with expanses of “empty” space in between.


Telescopes to study the stars: Telescopes to study the stars Space based telescopes look at light without the interference of the Earths atmosphere Different wavelengths show us different aspects of stars, and other planetary bodies Different wavelengths gather more information for analysis and comparison. Infrared images of black holes at the center of galaxies from the Hubble Space Telescope


Telescopes continued…: Telescopes continued… Routinely telescopes will collect radiation from the radio, infrared, visible, UV, and x-ray ranges to obtain more information about our universe Visible UV radio Infrared Supernova


Assessment: Assessment What galaxy is Earth in? Name and describe the three types of galaxies. How is matter distributed in the Universe? Why do scientists look at stars in different wavelengths of electromagnetic radiation?