Additional Rotation and Revolution Notes (Including Moon Phases)

All bodies in the solar system are in constant motion.

Day

  • The Earth rotates on its axis as it revolves around the Sun. It takes approximately 24 hours, aday,for acomplete rotation to occur. This counterclockwise motion occurs from west to east, causing the Sun toappear to rise in the east and set in the west.

Year

  • While the Earth rotates on its axis, it is also revolving around the Sun. It takes 365 1⁄4 days (ayear), forthis motion/orbit to occur.
  • he Earth revolves around the Sun in anellipticalorbit.

Moon Phases

New Moon

  • The moon is lined up between the Earth and Sun
  • When the Moon is exactly lined up with the Sun (as viewed from Earth), we experience aneclipse
  • The illuminated half of the moon is facing away from the Earth, and therefore the part that faces us is all dark
  • The Moon and the Sun rise and set at about the same time

Waxing Crescent Moon

  • As the Moon moves around the Earth, we see more and more of the illuminated half
  • It looks as if the moon is getting bigger each night
  • The moon is smaller than a quarter moon
  • The Moon is waxing.

Quarter Moon

  • A week after the new moon, when the Moon has completed about a quarter of its turn around the Earth, we can seehalfof the illuminated part
  • From Earth, we are now looking at the sunlit side of the Moon from off to the side.
  • A quarter of the Moon
  • The first quarter phase.
  • The Moon is nowone-quarterof the way through the lunar month

Waxing Gibbous Moon

  • During the next week, we keep seeing more and more of the illuminated part of the Moon
  • Waxing gibbous
  • Gibbous means "humped"

Full Moon

  • Two weeks after the new moon, the moon is now halfway through its revolution around the Earth
  • The illuminated half is facing the Earth
  • We can see a full disk
  • Full moon
  • At this time the Moon rises at the time the Sun sets, and it sets when the Sun rises
  • If the Moon happens to align exactly with the Earth and Sun, then we get a lunar eclipse. the full sunlit face of the Moon.
  • The Moon has now completed one half of the lunar month

Waning Gibbous Moon

  • From this point, until it becomes new again, the illuminated part of the Moon that we can see gets smaller
  • A gibbous moon is larger than a quarter moon, but smaller than the full moon
  • Waning
  • The first week after the full moon, the phase is called waning gibbous

Last Quarter Moon

  • Three weeks after the new moon , we again can seehalfof the illuminated part
  • This is usually called last quarter
  • Sometimes called third quarter
  • The side that we saw dark at the first quarter phase is now the lit side

Waning Crescent Moon

  • During the fourth week, the Moon appears to get smaller and smaller
  • Waning crescent .