Universe Cycle - Universe (5)
Pre Lab 

   
OBJECTIVES:
  • Differentiating terms used to describe the Universe.
  • Comparing the components of the Universe.
VOCABULARY:
  • galaxy
  • globular cluster
  • white dwarf star
  • neutron star
  • black hole
  • binary star
  • main sequence star
  • quasar
  • pulsar
  • planet
  • solar system
  • asteroid
  • comet
MATERIALS:

Students use the Internet to learn about the Universe


A barred spiral galaxy

BACKGROUND:

The Universe contains many components, which vary considerably in size. In this exercise, students will use the internet to research definitions for a number of astronomical objects, which are listed in the "Vocabulary." Here are definitions to help you guide the studentís work.

A galaxy is a large scale aggregate of stars, plus some gas, dust, and possibly solar systems, which are held together by gravity.

A globular cluster is a roughly spherical group of hundreds of thousands to about a million stars, also held together by gravity. Globular clusters seem to be made of very old stars.

A star is a ball of hot gas held together by its own gravity. Gravity also causes stars to undergo nuclear fusion within their interior. The energy release causes the star to shine. The energy of fusion balances the starís gravity, preventing it from collapsing. However, when a starís internal energy dwindles, the star may fade from sight into a white dwarf star, or a neutron star, an extremely high density object composed of 99% neutrons. Neutron stars are probably remnants from supernova explosions. A pulsar is a rapidly spinning neutron star. For reasons that are not fully understood, pulsars emit regular bursts "pulses" of radiation.

Stars come in a variety of types. These include:

  1. Binary Stars - A system of two stars, orbiting around one another. Binary (and other multiples) stars are very common. Astronomers estimate that about half of all stars are members of multiple-star systems.
      
  2. Main Sequence Stars - Stars on the "main sequence" part of the Hertzprung-Russell (H-R) diagram, which classifies stars in terms of absolute magnitude and temperature. Main sequence stars get brighter as they get hotter. Our Sun and the majority of the stars in the Universe are on the Main Sequence.
      
  3. Giant and Supergiant Stars - Large stars that occur above the main sequence, which are unusually large and cool. Supergiant stars are brighter than giant stars.

    A quasar (short for quasi- stellar radio source) is a point source, no more than one light year in diameter that emits tremendous amounts of energy, as much as hundreds of galaxies. Current hypotheses suggest that quasars are powered by super massive black holes.

    A solar system is an arrangement of planets and other small bodies around a central star or stars. The planets are kept in place by gravity.

    A planet is a spherical body which circles a star in a regular orbit.

    A comet is a kilometer-scale mass of frozen gas and rock which orbits the Sun. Comets are leftovers from the formation of the Solar System.

    An asteroid is a mass of rock and minor amounts of frozen gas. Like comets, asteroids are leftovers from forming the planets. Most asteroids are in orbits between Mars and Jupiter. They range in size from dust specks to over 300 kilometers in length.

PROCEDURE:
  1. Have the students define the words on the worksheet using the Internet or other resources. We recommend the Internet because information on the Universe continues to increase as we develop new ways to gather data. Many sites on the Internet can allow students to easily learn the latest astronomical discoveries. You can easily do a search on each of the vocabulary words.
      
  2. You may want to use the following sites:
      
    http://oposite.stsci.edu/pubinfo/Anim.html 
    Animations of planets and galaxies. The home page for this site contains links to many Hubble Space Telescope pictures.
      
    http://www.damtp.cam.ac.uk/user/gr/public/ 
    Cambridge Relativity of Cambridge University. Discusses Cosmology, Black Holes, Inflation, Cosmic stings, and more. Good illustrations and graphics.
      
    http://windows.ivv.nasa.gov/
    Windows to the Universe from NASA - a comprehensive educational website for planetary science and astronomy.
     
    http://www.nationalgeographic.com/features/97/stars/ 
    Star Journey - a National Geographic site which includes star charts of the night time sky.
      
    http://www.astro.wisc.edu/~dolan/constellations/ 
    The Constellations and their Stars. A detailed website that includes interactive sky charts and pictures of stars and galaxies.

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