1. Earth, Moon, and Sun

2. Revolution and Rotation
Revolution – object’s path as it orbits another body in space
Earth’s revolution is 365 1/4 days (leap year)
Rotation – spin of an object in space
Earth spins about its axis (imaginary line through center of Earth from pole to pole)
Earth’s rotation is 23 hours and 56 minutes
Day – time required for Earth to rotate once on its axis

3. Earth’s Position and the Sun
Earth is positioned so half of the planet is lit (pointing towards the Sun) and half is dark (pointing away from the Sun)
The Sun’s rays
hit the Earth more directly at the equator, that is why it is hotter
are dispersed at the poles, that is why it is colder
The Seasons
23.5° tilt causes the seasons
Has nothing to do with how close to the sun we are
The North Hemisphere points away from the Sun in the winter
Equinox – Sun directly above the equator
Solstice – Sun farthest North or South of the equator

4. Season’s Yearly Cycle March Equinox (March 21st)
Vernal Equinox – spring begins in northern hemisphere
Daylight hours equal night hours
June Solstice (June 22)
Summer Solstice – summer begins in northern hemisphere
North pole pointed towards Sun
More daylight hours in northern hemisphere
September Equinox (September 23)
Autumnal Equinox – fall (autumn) begins in northern hemisphere
Neither Northern or Southern hemisphere are pointed towards the Sun
December Solstice (December 22)
Winter Solstice – winter begins in northern hemisphere
North pole pointed away from Sun
Fewer daylight hours in northern hemisphere

6. Moon Phases Moon has revolution around Earth which equals 27.3 days
Moon rotates on its axis at the same rate (about 27 days)
Phases of Moon – different appearances of moon due to its changing position
Waxing – sunlit part of the moon gets larger
Waning – sunlit part of the moon gets smaller
Gibbous - almost fully lit
Cresent – cresent, sliver shaped

7. Eclipses Eclipse – shadow of celestial body falls on another body
Lunar Eclipse
Earth comes between Sun and Moon
Shadow of Earth falls on Moon
Moon appears red because of Earth’s atmosphere reflecting the sunlight
Solar Eclipse
Moon comes between Earth and Sun
Shadow of moon falls on Earth

8. Moon and Tides
Earth and Moon pull together due to gravity (force of attraction between two objects)
Tides – daily movements of ocean water that change the level of ocean’s surface
On the side of Earth that faces the Moon, the ocean water bulges due to gravitational pull (same on opposite side of Earth due to the fact that Earth spins)
2 high tides and 2 low tides a day
Sun helps a little too
Tidal Range – difference between levels of ocean water at high and low tide
Spring tides – tides with the greatest tidal range
Neap tides – tides with the smallest tidal range