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The Earth, Moon, and Sun Ch. 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 ________. revolution. rotation.
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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 ________. revolution rotation rotates axis revolves sun orbit
How Does Earth Move? rotation • The __________ of Earth causes us to have ___________ every ______. • The ________ of Earth every ______ ___ causes us to have a _________. 24 hrs day & night revolution 365 ¼ day year
The History of the Calendar: Egyptians • ___________: • 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.
The History of the Calendar: Romans • __________: • Used the Egyptian calendar but adjusted it to add ¼ of a day (“leap year”).
The History of the Calendar: Gregorian • __________: • The calendar we use today, based off the Roman calendar but adjusted by 11 minutes a year. • Named after Pope Gregory XII
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 Equator poles seasons axis 23.5
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. solstice north summer June south winter Dec.
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 equal hours equinox vernal March autumnal Sept.
The Earth & Moon Ch 15 Lesson 2
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
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
Lunar Eclipse Solar Eclipse
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 Neap tide: Smaller difference between high and low tides that occur during quarter phases. 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.
Low Tide High 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.