Astrophysics


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  • Astronomy
    • The Solar  System
      • The Solar System consists of the Sun and all the objects that orbit it. This includes the 8 planets, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. And lots of dwarf planets, like Pluto! And their moons and comets and asteroids.
      • Planets and Moons
        • A  planet is a very large spherical object that orbits a star which has cleared its surrounding of debris.
          • A moon is a natural satellite of a planet.
      • Asteroids And Comets
        • An asteroid is a rocky minor planet. It orbits the Sun between Mars and Jupiter in the Asteroid belt/beyond Neptune in the Kuiper belt
          • A comet is a small, icy body, made up of rock. Tis held together by frozen gases and water, that orbits the sun. Has a highly elliptical orbit.
            • Comets spend a lot of time far from the Sun. They plunge inwards to pass around the Sun, and then return to the cold outer reaches of the Solar System.
    • Gravity and Orbits
      • Pluto's orbit is surrounded by smaller objects, that hasn't been cleared by its gravitational field.
        • Mass is the amount of matter in an object and is measured in kilograms. Mass isn't a force and has the same value anywhere in the Universe,
          • Weight is a force caused by the pull of gravity acting on a mass. Weight is measured in newtons, + has both magnitude and direction.   Weight has different values depending on where the object is in the universe.
            • W = m x g     weight of object = mass of object x acceleration of gravity.
              • Your weight is the force of gravity acting on you. It depends on both your mass and the gravitational field strength of the planet / object you are on. The surface gravity of a body depends on...
                • Satellites -     The force acting on satellites is gravity. Orbits that are close to the Earth, have a greater force of gravity, since they are going the fastest.
                  • 2 types of satellites  ~ Polar orbits and Geostationary orbits.
                    • Polar orbits   has low orbits, moves around the poles, moves very fast, an orbit takes up to an hour.
                      • Uses~ Weather monitoring, Mapping, Spying. The red light appears when the satellite is gathering intelligence.
                        • Polar orbits are used for mapping the earth because the is rotating on its axis, and is very rapid in rotating. And simultaneousl-y the polar orbits move around the poles rapidly, so that, you get a different view each time.
                          • Geostatiomary orbits don't need a dish to track a satellite, has a high orbit, moves around the equator, takes up to 24 hours, moves @ 3020 m/s. And it is always over the same point on earth.
    • Redshift
      • The colour of light depends on its wave length; red light has a longer wavelength than blue.
        • frequency x wavelength = speed of wavelength.
          • The Doppler Effect = the apparent change in frequency/ wavelength due to relative motion between source and observer. The change in frequency and wavelength of a wave as it moves towards or away from you
            • High frequency -  low frequency     If source move towards observer-high frequency            if. If source moves away from observer-low frequency.  .
              • When light is emitted from the galaxy it travels towards Earth.
                • When  this  light is blue shifted, the galaxy moves towards Earth.
                  • Hubble's Law - The recession velocity of a galaxy is directly proportional to its distance from the Earth.
                    • V=(const) d.     Hubble's Constant.
                      • The Expanding Universe - Every galaxy is moving away from every other galaxy.
                        • Redshift - Galaxies are moving away       Hubble's Law- The more distant a galaxy the faster it is moving.
                          • We can remember this as a bun with currants after putting it in the oven, every currant is away from other currant. The universe must be expanding if every galaxies moving away from each other.
    • Absorption Spectra
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