The Earth, Moon,and SunCh. 15

How Does Earth Move?•Earth moves in space in two

major ways: __________ and __________.– Earth _________ on its _______ (the

imaginary line passing through the N & S pole)

– Earth _________ around the _______ on an elliptical ________.

rotation revolutionrotates axis

revolves

sunorbit

How Does Earth Move?•The __________ of Earth causes us

to have ___________ every ______.

•The ________ of Earth every ______ ___ causes us to have a _________.

rotationday & night

24 hrs

revolution

365 ¼day

year

The History of the Calendar:

•___________:– based their calendar on star

motion and calculated about 365 days. They broke them into 12 months with an extra 5 days at the end.

Egyptians

The History of the Calendar:

•__________:– Used the Egyptian calendar but

adjusted it to add ¼ of a day (“leap year”).

Romans

The History of the Calendar:

•__________:– The calendar we use today, based

off the Roman calendar but adjusted by 11 minutes a year.•Named after Pope Gregory XII

Gregorian

Planetary Movement

What Causes the Seasons?•The sun rays hit’s Earth’s surface

________ (more at the ______ than at the ____).

•Earth has _______ because its _____ is tilted at ____ degrees as it revolves around the sun.

unevenly Equatorpoles

seasons axis23.5

Earth’s Seasons• The sun appears farthest north once

a year and farthest south once a year; this is known as the _______.

• In the Northern Hemisphere when:– the sun is farthest ______ it is the

_______ solstice (around ______ 21st) and we have the longest day.

– the sun is farthest ______ it is the _______ solstice (around ______ 21st) and we have the shortest day.

Dec.

north summerJune

south winter

solstice

Earth’s Seasons•Halfway between the solstices

neither hemisphere is tilted toward the sun, and we have __________in the day and night. This is known as the _______. – the _______ (or spring) occurs around

______ 21st

– the ________ (or fall) occurs around ______ 21st Sept.

equinoxvernal

Marchautumna

l

equal hours

Seasons in the N and S

The Earth & Moon

Ch 15 Lesson 2

The Moon Dance

The Moon’s Formation

Rotation and Revolution• The Moon rotates on its axis and

revolves around the Earth, just as the Earth revolves around the Sun.

• The Moon’s rotation takes 27.3 days around Earth.

• It takes about 29.5 days for the Moon to complete the cycle of phases.

Moon Phases• Moon phases are the different forms that

the Moon takes in its appearance from Earth

• There are 4 main phases of the Moon: – New: occurs when the Moon is between

Earth and the Sun– Waxing: means that more of the half

moon can be seen each night– Waning: means that less of the half

moon can be seen each night– Full: occurs when all of the Moon’s

surface facing Earth reflects light

Moon Phases

Moon Phases…cont.

Eclipses• There are two types of eclipses

– Solar eclipse: occurs when the Moon moves directly between the Sun and Earth and casts its shadow over part of Earth•Umbra: the darkest part of the Moon’s shadow

•Penumbra: a partial solar eclipse seen from Earth

– Lunar eclipse: when Earth’s shadow falls on the Moon

Total Eclipse

Solar Eclipse

Lunar Eclipse

http://home.hiwaay.net/~krcool/Astro/moon/moonorange/

The MoonIt’s Affect on the Oceans

• The Earth and the Moon are attracted to each other like magnets. The Earth has a gravitational field that holds objects to it’s surface, but water is always moving therefore can not be held down.

• Tides are the periodic rise and fall of the ocean waters. High and Low tides occur because of the Moon’s gravitational pull.

• The ocean moves between high & low tides, about 12 hours 25 minutes b/w the two.

Spring & Neap Tides

Spring tide: When the Earth, Moon, and Sun are aligned to cause exceptionally high and low tides. This happens during the Full and New Moon.

Neap tide: Smaller difference between high and low tides that occur during quarter phases.

Moon & Tides

High Tide

Low Tide

The Importance of Understanding the Tides

• Commercial and recreational fisherman use their knowledge of tides and tidal currents to help them improve their catches.

• Ships navigating through shallow water ports and waterways must be knowledgeable of the time and height of the tides as well as the speed and direction of the currents.

• Oceanographers study tidal fluctuations to better understand the ocean circulation and relationship to world climate issues.