Space Physics - Key Terms

    Cards (10)

    • Universe
      all existing matter, energy and space
    • Galaxy
      a collection of millions / billions of stars held together by gravitational attraction
    • Nebula
      a cloud of particles and gases
    • Protostar
      the hot dense mass that forms when a nebula collapses, which evolves into a star once nuclear fusion can occur
    • Main sequence
      a stable period in the lifecycle of a star, during which the outward acting fusion energy and inward acting force of gravity are in balance
    • Supernova
      a large star that explodes because the forces within it are no longer balanced / stable, releasing vast amounts of energy
    • Orbit
      the curved path followed by a planet, satellite, comet, etc. as it travels around a body that exerts a gravitational force upon it; also applies to the paths of electrons around a nucleus (which exerts an electrostatic force of attraction)
    • Circular motion
      produced when an object rotates with a constant speed but changing velocity; the instantaneous velocity is perpendicular to the centripetal force
    • Body
      an object that has three dimensions and mass
    • Red-shift
      the observed increase in the wavelength of light from distant galaxies, towards the red end of the spectrum