Astronomy Test 1 Review - Universe, Galaxies, Stars, Solar System

    Things for Unit Test 1 you should UNDERSTAND, KNOW, and be able to DO...
    • As our technology has progressed, so has our understanding of celestial objects and events.
    • The Earth and Universe is in a constant state of change.
    • How can we understand things at great distances we can’t see or touch?
    • What is the scale of the universe?
    • What is the Earth and Sun’s position in the universe?
    • Gravity influences the motions of celestial objects. The force of gravity between two objects in the universe depends on their masses and the distance between them.
    • Eight planets move around the Sun in nearly circular orbits.
    • The universe is vast and estimated to be over ten billion years old. The current theory is that the universe was created from an explosion called the Big Bang. Evidence for this theory includes:
      • cosmic background radiation
      • a red-shift (the Doppler effect) in the light from very distant galaxies.
    • Stars form when gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier ones occurs. Fusion releases great amounts of energy over millions of years.
      • The stars differ from each other in size, temperature, and age.
      • Our Sun is a medium-sized star within a spiral galaxy of stars known as the Milky Way. Our galaxy contains billions of stars, and the universe contains billions of such galaxies.
    • Our solar system formed about five billion years ago from a giant cloud of gas and debris. Gravity caused Earth and the other planets to become layered according to density differences in their materials.
      • The characteristics of the planets of the solar system are affected by each planet’s location in relationship to the Sun.
      • The terrestrial planets are small, rocky, and dense. The Jovian planets are large, gaseous, and of low density.
    • Asteroids, comets, and meteors are components of our solar system.
    Vocab Terms: Background Radiation, Big Bang theory, blue shift, celestial object, Doppler effect, electromagnetic spectrum (radiation), galaxies, light year, luminosity, magnitude, main sequence star, radiation, red shift, star life cycle, stellar life cycle, supernova, telescope, gravity, asteroid, constellation, Rotation, Revolution, Jovian and Terrestrial Planets
    • Classify stars based upon luminosity and temperature
    • Classify planets