magnet

~Earth Layers~

INNER CORE Iron and Nickel Magnetic Solid	OUTER CORE Iron and Nickel Magnetic Liquid Cause of Earth's Magnetic Field
LOWER/MID-MANTLE Aesthenosphere Soft/Magma Exhibits "Plasticity" Convection Currents	UPPER-MANTLE Lithosphere Rigid/Solid Moho Boundary
OCEANIC CRUST Dark-Colored Rock Sample: Basalt More Dense Fine-Textured Thin Layer	CONTINENTAL CRUST Light-Colored Rock Sample: Granite Less Dense Coarse-Textured Thick Layer

Continental Crust: 40 - 70 km thick / Density = 2.7 gm/cm3

Oceanic Crust: 5 km thick / Density = 3.0 gm/cm3

Upper Mantle: 660 km thick / Density = 3.3 gm/cm3

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~Convection in the Mantle~

Hot matter rises, then cools and sinks.

Click here: Mantle Convection Video Clips / Video

Click here: Seussville / Other Slime Recipes / Oobleck

Oobleck simulates "Plasticity" in the Mantle:

* Under Conditions of High Temperature ~~~> flowing liquid

* Under Conditions of High Pressure ---> rigid solid

Q: What is the source of movement in the Earth's crust?

A: Convection Currents in the Mantle.

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Fun Fact:

Scientists have only drilled 14.16 kilometers (8.8 miles) into the Earth.

Learn More: Deepest Hole / Gravity Express Train / Superdeep Borehole

Question: How do people know what the core and mantle are like... if we have never drilled down that deep?

Answer: Direct evidence from rock samples and indirect evidence from seismic (earthquake) waves.

Click here: Earth's Interior

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~Iron and Nickel~

IRON

Symbol (Fe)
Magnetic Metal
Used in making steel
Atomic Number: 26
Forms Rust: (Fe2O3)
Learn more: Iron

Iron Filings

Iron Ore

Old-Fashioned Iron

Antique Coal Iron

Steel Beams

NICKEL

Symbol (Ni)
Magnetic Metal
Used in making steel
Atomic Number: 28
Used in batteries
Learn more: Nickel

Nickel Filings

Nickel Ore

Nickel Coin Composition:

75% Copper 25% Nickel

Nickel Foil

Nickel-Cadmium Battery

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~Solar Radiation and Earth's Magnetosphere~

Solar radiation being deflected by Earth's protective magnetic field

Van Allen Radiation Belt

Click here: MagnetosphereA / MagnetosphereB

The Magnetosphere Provides Protection

A Solar Flare can Disrupt Satellite Communications

Solar Flare and Earth's Magnetic Field

Coronal Mass Ejection (CME): Solar Flare

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~Aurora Borealis: Northern Lights~

~Aurora Australis: Southern Lights~

Click here for: Aurora Gallery / Cause of Aurora

Solar Radiation excites Molecules in the Upper Atmosphere

Aurora as seen from the Space Shuttle

Ring of Aurora Australis (Southern Lights) at Earth's South Pole

Above: Close up of Aurora on Jupiter

Below: Auroras on Jupiter and Saturn

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~Magnetic Compass and Orienteering~

Click here: Letterboxing - a Geographic Scavenger Hunt

Click here: Lobster Magnet Song

Van Allen Radiation Belt

The South Pole of a Magnet is Attracted to the North Magnetic Pole of Earth

Topographic Map and Compass

"Put the RED in the shed"

Compass Rose

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~Magnetic Pole Reversals~

Click here: Sea Floor Spreading Video

Magnetic Pole Reversals

Like all magnets, Earth's magnetic field has two opposing regions, or poles, positioned approximately near geographical North and South Poles. During a period of normal polarity the region of attraction corresponds with the North Pole.

Today, a compass needle, like other magnetic materials, aligns itself parallel to the magnetizing force and points to the North Pole. During a period of reversed polarity, the region of attraction would change to the South Pole and the needle of a compass would point south.

Studies of the magnetism retained in rocks at the time of their formation (like small compasses frozen in time) have shown that the polarity of the magnetic field has reversed repeatedly throughout geological time.

The reason for polar reversals is not known. Although the average time between reversals over the last 10 million years has been 250,000 years, the rate of reversal has changed continuously over geological time. The most recent reversal was 780,000 years ago; scientists have no way of predicting when the next reversal will occur. The reversal process probably takes a few thousand years.

Learn more: Magnetic Flip-Flop / Historical Chart

And more: Nova - Magnetic Storm

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~Bar Magnets~

The Earth Acts like a Giant Bar Magnet

Magnetic Force Field Lines in Two Dimensions (Iron Filings)

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~Magnetic Domains~

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(N--> * <--S) OPPOSITE POLES ATTRACT (S--> * <--N)

(S<-- * --> S) LIKE POLES REPEL (N<-- * --> N)

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~Iron in Breakfast Cereals~

Click here for: Eat your Breakfast Metals / Iron in Cereals

Plastic-Coated Magnet

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~Links~

Click here for: Magnetism Animation

Click here for: Megamagnetmania

Click here for: Dietary Iron

Click here for: Multi-Links

Click here for: More Magnet Games

Click here for: Create your own Compass

~Foods that Contain Iron~

Spinach, Kale and Broccoli

(dark green leafy vegetables)

~*~

Red Meat

~*~

Iron-Fortified Breads, Cereals and Pasta

Food Pyramid

~Animals Affected by Magnetism~

It has been demonstrated that such diverse creatures as homing pigeons, salamanders, bats and bees can detect a magnetic field.
For more information, click here: Magnetism and Animals

~Birds~

Scientists believe that migratory birds, like these Canada geese, may use the Earth's magnetic field to plan the dining locations along their migration routes.

~Bees~

The Earth's magnetic field changes on a daily cycle.
It is suspected that this cycle is used by bees to maintain their internal clock.
Sensitivity to the magnetic cycle would be especially useful to bees who remain inside the hive and are unable to detect sunrise and sunset.
It has been experimentally shown that subtle magnetic disturbances can disrupt the bee's time-keeping abilities.

~Fish~

It has been shown that sharks and salmon navigate using Earth's magnetic field.
Electromagnetic sensitivity requires a medium of high electric conductivity. The salt water habitat of marine animals provides a means for such condictivity.
When fish swim in the ocean, they cross geomagnetic field lines, which creates electric voltages in their bodies.
It has been found that certain fish, namely sharks, rays, and skates, use this phenomenon to navigate in ocean waters.
Scientific studies have found that electromagnetic receptor organs in certain fish are sensitive to voltage differences in a magnetic field.

~Sea Turtles~

Sea turtles have an extraordinary sense of time and location.
They are highly sensitive to the Earth's magnetic field and use it to navigate.
They can live up to 189 years.
The fact that most species return to nest at the locations where they were born seems to indicate an imprint of that location's magnetic features.

Loggerhead Sea Turtle

Hawaiian Green Sea Turtle

All Species of Sea Turtles are Threatened or Endangered