space 1

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space 1
2012-12-16 12:31:36

chapter 7
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  1. Celestial object
    Any object that exists in space, such as a planet,a star, or the Moon
  2. Astronomer
    A scientist who studies astronomy
  3. Revolution
    • The time it takes for an object to orbit another object
    • e.g. Earth's revolution around the Sun is 365.24 days
  4. Rotation
    • The turning of an object around an imaginary axis running through it
    • e.g. Earth'd rotation around its axis is 24 h
  5. Constellation
    A group of stars that seem to form a distictive pattern in the sky
  6. Light-year
    The distance that travels in one year, about 9.5 x 10^12 kn
  7. Apparent magnitude
    The brightness of a star as seen from Earth
  8. Asterism
    A smaller group of stars that form patterns within a constellation
  9. Pointer stars
    The Bid Dipper's two end stars are called pointer stars because they point towards Polaris, the North Star.

    (You can find Polaris using the pointer stars)
  10. Tides
    The rising and falling of ocean waters caused by the Moon's and Earth's gravity
  11. Phases of the moon
    • the monthly progression of changees in the appearance of the Moon that result from different portions of theMoon's sunlit side being visible from Earth
  12. Lunar eclipse
    The phenomenon in which the full Moon passes into Earth's shadow
  13. Solar eclipse
    The phenomenon in which the shadow of the Moon falls on Earth's surface
  14. Why do we have seasons?
    Because Earth does not rotate in an upright position, its tilted on its axis. In the summer months, the northern hemisphere is tilted towards the Sun. In the winter months the northern hemisphere is tilted away from the Sun. 
  15. Planet (include inner planet & outer planet)
    A planet is an object that orbits one or more stars(and is not a star itself), is spherical, and does not share its orbit with another object

    Inner planets in our solar system include: Mercury, Venus, Earth and Mars

    Outer planets in our solar system include: Jupiter, Saturn,Uranus and Neptune
  16. Solar system
    A group of planets that circle one or more stars
  17. Retrograde motion
    The movement of an object in the sky, usually from a planet, from east to west, rather than its normal motion from west to east; this effect is generally produced when Eath is passing the planet in its orbit
  18. Astronomical unit
    The average distance between Earth and the Sun, about 150 x 10^6 km
  19. Orbital radius
    The average distance between the Sun and an object that is orbiting the Sun
  20. Geocentric model
    • A model of the solar system stating that Earth is the centre of all planetary motion, with the plantes and the Sun travelling in perfect circles around Earth
  21. Heliocentric model
    • A model of the solar system in which the Sun is in the centre with the planets orbiting it in perfect circles.
  22. Comet
    An object composed of ricky material, ice, and gas; comes from the Kuiper Best or Oort Cloud
  23. Asteroid
    An object in space that ranges in size from a tiny speck, like a grain of sand, to 500 km wide; most asteriods originate in the asteriod best between Mars and Jupiter
  24. Meteoroid
    A piece of rock moving through space
  25. Meteor
    A meteoroid that hits Eaths's atmosphere and burns up
  26. Meteorite
    A metereoroid that is large enough to pass through Earth's atmosphere and reach the ground, without being totally burned up
  27. Trans-Neptunian object
    An object that circles the Sun beyond the orbit of Neptune