Earth, Space and Magnetism Magnets Earth, Space and Magnetism

How could Earth’s magnetic fields trigger volcanic activity?

Noncontact Forces •What are examples of forces (pushes or pulls) you see in your everyday life? •Can you think of a force that you see every day that’s not a contact force? •Do you think those forces gain or lose strength as the distance between the interacting objects changes? This is a discussion slide

https://www.youtube.com/watch?v=8PyqL9y7VZo

Notes from video Magnets come from minerals found in earth Earth is a giant mineral Three significant metals can become magnetized Iron Nickel Cobalt Magnetism is a form of energy

Magnetism Magnets attract and repel each other Only certain materials are magnetic Caused by spinning electrons Most materials… half of the electrons spin one way, half the other way Other a(iron, nickel, cobalt)… most of the electrons spin the same direction – these materials are “magnetic”

Magnetism (continued) “Magnetic” and “magnetized” are different “magnetic” substance must be “magnetized” in order for it to become a magnet How? Another strongly “magnetic” substance must enter its magnetic field Can also be magnetized by an electrical current, but only until the current is turned off Electric currents generate magnetic field

Magnetism vs. Gravity How are they the same? How are they different? Both noncontact forces Both decrease in strength as objects move away from each other Earth’s outer core must be moving in order to create electric current and Earth’s magnetic field Movement of outer core relies on the force of gravity How are they different? Gravity exists in all objects that have mass Magnetism depends on the properties of the substance Magnetism can work in 2 directions, gravity only works in 1 direction Magnetism affected by alignment of electrons in object, gravity only depends on gravitational force

Magnetism vs. Gravity How are they the same? How are they different? Both noncontact forces Both decrease in strength as objects move away from each other How are they different? Gravity exists in all objects that have mass Magnetism depends on the properties of the substance Magnetism can work in 2 directions, gravity only works in 1 direction

https://www.youtube.com/watch?v=yEYy_nVC4L0

Discussion questions Earth has an iron core gives it magnetic field Inner Core: solid iron due to pressure of gravity Outer Core: liquid iron, nickel and trace metals Flow of liquid iron creates electrical currents What role do these electrical currents play in the magnetic field of the Earth? How does the Earth’s core act like an electric generator? Answer to 2nd question: as core flows through the geomagnetic field the motion creates electric current; which creates a magnetic field

History of Earth’s Magnetic Field Geomagnetic poles don’t align with the Earth’s North and South Poles Breakdown the word “geomagnetic” : What do you think it means? Geomagnetic poles spontaneously change due to activity beneath the Earth’s surface Volcanic rock has a significant amount of magnetic particles Earth’s geomagnetic poles recorded in volcanic rock How do you think the rock records Earth’s magnetic field at a certain period of time?

History of Earth’s Magnetic Field (continued) As the lava cools it become solid rock The strongly magnetic particles line up along Earth’s field Their arrangement and direction they point is what enables us to see what the magnetic north and south poles were during the time the rock was formed

Space View of Earth’s Magnetic Rocks Depiction of the magnetism in Earth’s rocks: http://www.bbc.com/news/science-environment-39340609 Map constructed using data from the European Swarm satellite Stripes of magnetism seen where new crust is constantly formed Shows the change in Earth’s magnetic poles over time - provides evidence for plate tectonics Detection from space is difficult - magnetic field of molten core interferes with magnetic field of the crust Certain regions have a much stronger magnetic field Example #1: Bangui anomaly in western Africa Possible impact site of a large iron asteroid over 500 million years ago Example #2: Kursk anomaly in central Russia Substantial amount of iron mined

Space Technology and Earth’s Magnetic Field Swarm trio of satellites (European Space Agency) currently measuring Earth’s magnetic field Provides data for maps of magnetism in Earth’s crust Why is this important information to have? Magnetism also generated by electric fields high above the Earth Our magnetic field helps protect us from the intensity of the sun Very subtle effect on Earth’s magnetism caused by movement of salt water ocean currents Why do you think salt water currents would affect Earth’s magnetism? Question answers: #1. understanding the distribution of commercially important mineral resources and investigating Earth’s geological history, understand large-scale tectonics better #2. Movement of salt water can conduct electricity, this electrical current affects the Earth’s magnetic field

Space Technology and Magnetic Observatories Observatories worldwide measuring Earth’s magnetic field at its surface and in space Study of the magnetic field in and around Earth’s atmosphere = space weather Observatories give real-time data of strength of magnetic field Satellite magnetometers measure Earth’s magnetic field in space

Volcanoes and Earth’s Magnetic Field Are volcanoes caused by tectonic plates pushing together or sliding apart? Why does this movement cause volcanoes? The Earth and sun’s magnetic fields are weakening How could this affect the number of erupting volcanos? Sea-floor spreading and volcanic material show changes in Earth’s magnetic field Answers to questions: #1. Both, but plates that slide apart are going to usually have more active volcanoes #2. New crust formed to fill the gap Connections of magnets and volcanoes: If magnetic field weakening, could indicate a flip is nearing, the weakening allows the sun to heat up the Earth, increases temperature of the Earth’s mantle, temperature increases that causes sea floor spreading and increased volcanic activity.

Instructional Segment 2: Essential Question “How could gravity and energy flow affect volcanic eruptions and mass extinctions?” How can what you learned today about magnetism (a form of energy), gravity and the Earth’s layering help answer this question? Looking back at Instructional Segment #1… is magnetism potential or kinetic energy? What about gravity?

Resources http://www.physics.org/article-questions.asp?id=64 https://www.nationalgeographic.org/encyclopedia/magnetism/ http://www.bbc.com/news/science-environment-39340609 https://www.youtube.com/watch?v=BCzCmldiaWQ http://www.cam.ac.uk/research/news/increase-in-volcanic-eruptions-at-the-end-of- the-ice-age-caused-by-melting-ice-caps-and-glacial