astronomy

phases of the moon/ tides/ eclipses/ seasons

Phases Of The moon

waxing and waning
  • waxing means growing or expanding illumination
  • waning means shrinking or decreasing
crescent and gibbous
  • crescent means less than half illuminated
  • gibbous means more than half illuminated
lunar cycle
  • this cycle takes 29.5 days. The moon completes its orbit around the earth in 27.3 days (sidereal month) but the earth has not finished its orbit around the sun (synodic) cycle until it reaches the point in its orbit where the sun is in the same position.
Mr. Lee - Phases of the Moon rap
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TIdes

Neap and Spring tides
  • Neap tides: Especially week tides. The sun and moon are perpendicular to each other. They occur during quarter moons.
  • Spring tides: Especially strong tides. Occur when the Earth, moon, and sun are in line. Occur during the full moon and new moon.
Semildiurnal and Diurnal tides
  • Semildiurnal tides: Two high tides and two low tides in one day.
  • Diurnal tides: One high tide and one low tide in one day.
Sun and moon impact on tides
  • The sun impacts tides because its gravitational pull can heighten the moons effects or counteract them depending on where the moon is in relation to the sun.
  • The moon impacts tides because its gravitational pull causes the rise and fall of the water. The side of the earth that faces the moon will have slight bulge in the water.
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Eclipses

lunar and solar


  • Lunar eclipse: The moon is in the earth's shadow
  • Solar eclipse: The moon is between the earth and the sun.
penumbra and umbra shadows



  • Penumbra shadow: slight darkening of the moon
  • umbra shadows: all light is blocked

Seasons

Revolution and rotation
  • Revolution is the movement of one object around the center of another object. Example: the earth moving around the sun or the moon moving around the earth
  • Earth rotates on its axis. One rotation is one day (24 hours)
Axis
  • We have seasons because of the tilt of the earth's axis. The Earth's axis is tilted at an angle of 23.5 degrees. The axis is an imaginary line between the north and south poles
Why is a year a year
  • A year is the time it takes the earth to orbit the sun. The Earth's orbit around the sun takes 365.24 days. The .25 becomes an extra day on February 29, every 4th year (leap year)
Northern hemisphere and southern hemisphere and equator


  • Right now in the northern hemisphere it is winter but over on the other side of the world (the Southern hemisphere) its summer.
  • The equator is an imagery line drawn around the center of the earth equally distance from both poles, dividing the Northern and Southern hemispheres.
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Why do we have seasons?