chap 7

  1. Celestial object
    Any object that exists in space
  2. Astronomer
    A scientist who studies space.
  3. Revolution
    The time it takes for an object to orbit another object.Earth's revolution takes 364 ¼ days.
  4. Rotation
    The turning of an object around an imaginary axis running through the centre. Earths rotation takes 24 hours
  5. Constellation
    A group of starts that seem to make a distinct pattern in the sky
  6. Light year.
    The time light travels in a year. Equal to about 9.5 x 1012 
  7. Apparent magnitude
    The brightness of a star from perspective on earth.
  8. Asterism
    A constellation inside a constellation or between two or more constellations.
  9. Pointer stars
    A star or group of stars that point in a certain direction and are used to tell direction.
  10. Tides
    The rise or fall of the water in the sea due to the gravitational interaction of the moon and the earth.
  11. Phases of the moon
    The monthly progression of changes in the appearance of the Moon that result from different portions of the Moon's sunlight side being visible.
  12. Lunar eclipse
    The phenomenon in which the moon appears darkened as it passes into the earth's shadow.
  13. Solar Eclipse
  14. The phenomenon in which the sun is obscured by the moon.
  15. Whats the reason for the seasons.
    • The Earth's axis is tilted at an angle of 23.5 degrees. This means that the Earth is always "pointing" to one side as it goes around the Sun. When North America is pointing to the sun we are getting direct sunlight this creates hotter temperatures. This
    • happens during our summer months.
  16. Planet (include inner planet & outer planet)
    A celestial body moving in an elliptical orbit around one or more star. Does Not share its orbit with other objects. Inner planet - a planet whose orbit lies within the asteroid belt, i.e., Mercury, Venus, Earth, or Mars. Outer planet - a planet whose orbit lies outside the asteroid belt, i.e., Jupiter, Saturn, Uranus, or Neptune
  17. Retrograde motion
    The movement of a planet from east to west rather than its normal west to east usually due to earth passing this planet in its orbit. 
  18. Astronomical Unit
    The average distance between earth and the sun. Equal to 150 x 10 to the power of 6  
  19. Orbital radius
    The average distance between the sun and an object orbiting the sun.
  20. Geocentric model
    A model of the solar system stating that the earth is the centre of all planetary motion and the sun and planets orbit the earth in perfect circles.
  21. Heliocentric model
    A model of the solar system stating that the sun is the centre of all planetary motion and the earth and other planets orbit the earth in perfect circles.
  22. Comet
    An object composed of rocky material, Ice, and gas comes from the Kuiper Belt or Oort Cloud.
  23. Asteroid
    An object in space that ranges from a tiny spec like a grain of sand to 500 km wide; most asteroids originate in the asteroid belt between mars and Jupiter.
  24. Meteroid
    A piece of rock moving through space.
  25. Meteor
    A meteoroid that enters earth's atmosphere
  26. Meterite
    A meteoroid that enters earth's atmosphere and reaches the ground.
  27. Trans-Neptunian Object
    An object that circles the sun beyond neptune.
Card Set
chap 7