Earth and Moon NotesChapter 24

GRAVITYGRAVITY

• Causes spherical shape of planets

• Decreases as items move farther apart

• Increases with size of objects

RotationRotation

• Movement on an axis

• Causes day and night

• Takes 24 hours (one day) to complete one rotation (or 23 hours 56 minutes)

RevolutionRevolution

• 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)

EARTHEARTH

• The orbit is elliptical (oval) in shape

• The tilt is 23.5º and always points toward the north star

SolsticeSolstice

• Time when the sun is the furthest distance from the earth.

• Summer solstice – Longest day, June 21st or 22nd, Northern hemisphere’s toward the sun

• Winter solstice – Shortest day, December 21st or 22nd, Southern hemisphere toward the sun

EquinoxEquinox

• The sun is directly over the earth’s equator.

• The tilt is not toward or away from the sun.

• Spring equinox – March 21 or 22nd

• Fall equinox – September 21st or 22nd

MoonMoon

• 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: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 PhasesMoon Phases

It takes 29.5 days

to complete all eight

phases.

Moon PhasesMoon Phaseshttp://www.astro.wisc.edu/~dolan/java/MoonPhase.htmlhttp://www.astro.wisc.edu/~dolan/java/MoonPhase.html

New Moon Crescent waxing

1st QuarterGibbous waxing

Full Gibbous waning

Last (third) Quarter

Crescent waning

EclipseEclipse

• Solar Eclipse – earth moves into the moons shadow

• Lunar Eclipse – sun, moon & Earth are lined up with each other.

TidesTides

• 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

CREDITSCREDITS

• http://www.astro.wisc.edu/~dolan/java/MoonPhase.html