GRAVITY Causes spherical shape of planets Decreases as items move farther apart Increases with size of objects
Rotation Movement on an axis Causes day and night Takes 24 hours (one day) to complete one rotation (or 23 hours 56 minutes)
Revolution Movement around another body Earth around the sun Causes seasons 365 ¼ rotations (days) for one revolution Satellite – one body orbits another –(The earth is a satellite of the sun)
EARTH The orbit is elliptical (oval) in shape The tilt is 23.5º and always points toward the north star
Solstice Time when the sun is the furthest distance from the earth. Summer solstice – Longest day, June 21 st or 22 nd, Northern hemisphere’s toward the sun Winter solstice – Shortest day, December 21 st or 22 nd, Southern hemisphere toward the sun
Equinox The sun is directly over the earth’s equator. The tilt is not toward or away from the sun. Spring equinox – March 21 or 22 nd Fall equinox – September 21 st or 22 nd
Moon Maria – dark colored regions on the moon Craters – large depressions formed by meteors (meteorite when it falls to the earth) Moon rocks – give us clues on how the moon was formed
Moon continue: One rotation takes 27.3 days One revolution takes 27.3 days This means we will always see the same side of the moon
Moon Phases It takes 29.5 days to complete all eight phases.
Moon Phases http://www.astro.wisc.edu/~dolan/java/MoonPhase.html http://www.astro.wisc.edu/~dolan/java/MoonPhase.html New MoonCrescent waxing 1 st Quarter Gibbous waxing Full Gibbous waning Last (third) Quarter Crescent waning
Eclipse Solar Eclipse – earth moves into the moons shadow Lunar Eclipse – sun, moon & Earth are lined up with each other.
Tides Neap Tide –Earth, moon, and sun form a right angle –During the quarter moons –Weaker tides overall due to suns counter gravity Spring Tide –Earth, moon and sun are lined up –During Full and New moon –Stronger tides due to gravity from moon and sun