The Sun-Earth-Moon System

Earth

Properties of Earth The Earth is spherical – It is not a perfect sphere, though. It bulges at the equator and is flatter at the poles 2. All objects are attracted by gravity to the center of the Earth 3

More Properties of the Earth 3. The Earth has an axis – an imaginary vertical line around which the Earth spins 4. The spinning of Earth on its axis, or rotation, causes day and night to occur 4

Magnetic Field The Earth acts as though there is a giant bar magnet inside – possibly caused by the spinning of the Earth and it’s iron based core The Earth’s magnetic field protects us from solar radiation and solar storms The magnetic poles are not at the geographic poles 5

What causes changing seasons? Revolution – the Earth’s yearly orbit around the sun Ellipse – the stretched out oval shape of the Earth’s orbit 6

A Tilted Axis The number of daylight hours is greater for the half of the Earth that is tipped toward the sun The tilt of the Earth causes different parts of the Earth to receive different amounts of sunlight 7

Vocabulary Solstice – the day when the Sun reaches its greatest distance north or south of the equator Equinox – the day when the Sun is directly above the equator 8

The Moon – Earth’s Satellite

Motions of the Moon It takes 27.3 days for the Moon to rotate once on it’s axis It takes 27.3 days for the Moon to revolve once around the Earth So… We always see the same side of the Moon! The Moon appears to shine because it reflects light from the Sun 10

Phases of the Moon

Phases of the Moon Moon phases – the different forms the Moon takes in its appearance from Earth New Moon – occurs when the Moon is between the Earth and the Sun A new moon occurs when the lighted side of the moon is facing the Sun and the dark side is facing the Earth

Waxing Phases of the Moon Waxing – more of the lit half of the Moon can be seen each night Waxing Crescent – thin slice of the moon First Quarter – half of the lit side is visible Waxing Gibbous – more than ¼ of the Moon is visible Full Moon – all of the Moon’s surface facing the Earth reflects light 13

Waning Phases of the Moon Waning – less of the moon is visible each night Waning Gibbous – just after the full moon Third-Quarter – only half of the lit side of the Moon is visible Waning Crescent - just before there is a new moon

Lunar Cycle

Eclipse

Solar Eclipse A solar eclipse occurs when the Moon moves directly between the Sun and Earth and casts its shadow over part of the Earth The eclipse may be a total or partial eclipse Umbra – the darkest part of the Moon’s shadow Penumbra – the lighter area around the umbra

Lunar Eclipse Lunar Eclipse occurs when the Moon moves into the Earth’s penumbra and then enters into the umbra 18

The Earth’s Interior The Kola Superdeep Borehole is an abandoned Cold War attempt by the Soviets to drill to the center of the Earth. The hole was drilled between 1970 and 1994, is 9 inches wide and reaches a depth of approximately 7.5 miles (40,230 feet) below the Earth’s surface. Scientists are still analyzing the information they obtained while drillilng Geologists use seismic (earthquake) waves to study the interior of the Earth. Seismic waves travel at different speeds when the material they are moving through changes

Scientists study meteorites to learn about the Earth’s interior Meteorites were formed in the early solar system. Some meteorites are made up of iron and nickel which is what the core of the Earth is believed to be made up of Map showing major impact basins

Earth’s Spheres All of the Earth’s layers interact, so the Earth’s Earth’s Spheres All of the Earth’s layers interact, so the Earth’s surface is constantly changing Atmosphere –thin layer of air Hydrosphere – all the water on Earth Biosphere – all living things on Earth Lithosphere – solid part of the Earth

Layers of The Earth based on chemical composition Crust – thin brittle layer of Earth Mantle Core

Fun Facts About the Crust The crust is made up of 30 slow moving rocks The moving plates are from 5 to 25 miles (8 to 40 kilometers) thick

Crust – 2 types Oceanic Crust Made of basalt lava that flows onto the seafloor Between 3-8 miles thick

Continental Crust Average thickness – 22 miles Made of many different types of rocks Less dense than oceanic crust

Mantle Trivia The mantle is approximately 1800 miles (2880 kilometers) thick The temperature of the mantle is between 1600 degrees and 8000 degrees Fahrenheit (871-4,426° C

Earth’s Mantle Hot, solid rock The mantle is made mostly of the rock peridotite – a rock high in magnesium and iron

More on the Mantle Heat flows through the mantle through the process of convection

Core Trivia The outer core is a liquid made of melted iron and nickel. It is 1,400 miles (2,240 km) thick and reaches a temperature of 11,000°F (6087°C) The inner core is solid iron and nickel and is 800 miles across (1280 km) and has a temperature over 13.000 °F (7,200°C)

The Earth’s Core Density calculations show that Earth’s core is metal Seismic waves show that the inner core is a solid and the outer core is a liquid Metallic meteorites and the magnetic field are also clues about the makeup of the core