The Earth, Moon, and Sun

Gravity and Motion The force that pulls an apple to the ground also pulls satellites (including the moon and International Space Station) toward Earth, keeping them in orbit. Gravity attracts all objects toward one another. Newton’s Law of Universal Gravitation states that every object in the universe attracts every other object.

Gravity and Motion The strength of the force of gravity between two objects depends on two factors: The mass (amount of matter in an object) of the objects Earth is extremely massive and therefore exerts more force than you The distance between the objects The force of gravity decreases as the distance increases The further an object, the less gravity is exerted on the object

Gravity, Mass, and Weight

Gravity, Mass, and Weight The measure of the force of gravity on an object is called weight. If you go to the moon, what would change, your mass or your weight? Your WEIGHT would change depending on your location (like the moon) because the gravity is different there (1/6th as much) Why is gravity different on the moon than on Earth? The moon has less mass than Earth, so it also has less gravitational pull.

Orbital Motion of the Moon Newton concluded that inertia (1st Law of Motion) and gravity keep Earth in orbit around the sun, and the moon and ISS in orbit around Earth.

Earth in Space Ch 15 Lesson 2

How Does Earth Move? revolution rotation rotates axis revolves sun Earth moves in space in two major ways: __________ and __________. Earth _________ on its _______ (the imaginary line passing through the N & S pole) *Remember – to rotate means “to spin” Earth _________ around the _______ on an elliptical ________. *Remember – to revolve means “to go around something” rotation rotates axis revolves sun orbit

How Does Earth Move? rotation day & night 24 hrs revolution 365 ¼ days The __________ of Earth causes us to have ___________ every ______. The ________ of Earth every ______ ______ causes us to have a _________. day & night 24 hrs revolution 365 ¼ days year

Planetary Movement

What Causes the Seasons? unevenly 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. Equator poles seasons axis 23.5

In the Northern Hemisphere when: 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.

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 New: occurs when the Moon is between Earth and the Sun 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

Lunar Eclipse Solar Eclipse

15.3 Tides Ch 15 Lesson 2

The Moon It’s Affect on the Oceans The Earth and the Moon are attracted to each other because of gravity. 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.

Moon & Tides

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.

How the Universe works: secret history of the moon