# magnetism and the sun neiu 19 ~ nasa endeavour 5 march 2008

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• Magnetism and the SunNEIU 19 ~ NASA Endeavour 5 March 2008

• What do you know about Magnetism???

• Seeing MagnetismPlease observe and respond to the following questionsWhat is happening that is impacting the speed and direction of the iron filings?What did you observe about iron filings near the bar magnet?Why do you think that this happened?

• MagnetismForce of NatureAll atoms are magnetic meaning that they have charges moving within themFor an object to act as a MAGNET, the magnetic fields within it (charged particles) must align with one anotherIn order to line up, the charged particles must be able to move freely

• Charged ParticlesExternal Magnetic Field

• Is it Magnetized or Not?

• What Do Magnets Do?MAGNET WARS!!!

• What Do Magnets Do?Attract or repel other magnets (exert a force)

Attract other magnetic metals

Have at least 2 distinct ends (poles) eachLike poles repel, opposite poles attract!

Notes:Do not need to touch to exert force (can exert force through empty space)Can turn other magnetic metal objects into temporary magnets

• What is a Force?Force is a push or pull that causes a change in motion.

A Force Field is the pattern in space of how that force is felt by other objects.

Fundamental Forces arise from fundamental properties of matter: Gravity arise from Mass: mass attracts massElectric force arises from Charge: two kinds of charge (positive and negative), like charges repel and opposite charges attractGravitational field of a point of massElectric field of 2 opposite chargesElectric field of 2 like charges

• Describing the Earths Magnetic FieldIntroducing Magnetic Field Lines !!!

• Magnetic FieldMagnetic field of a Bar Magnet: 2 poles, called North and South

Dipole field

Field has direction: lines point away from N and toward SDefinition of a Pole: Where lines meet (converge)

e.g.: lines of longitude on a globe meet at poles

• Moving molten iron in Earths outer core causes most of Earths magnetic field.

Magnetic field poles are NOT aligned with geographic poles. They also wander and flip (500,000 yrs between flips, 10,000 yrs to complete flip).Earth: A Huge Bar Magnet

• Earths Magnetic Field

• The Suns Differential RotationThe Sun does not rotate as a solid body: its equator rotates once every 25 days, while regions near the poles rotate every 30 days.

• Your Hypothesis: What happens to the Suns Magnetic Field?Follow the North/South Field LinesWhat begins to happen?

• The Suns Magnetic FieldImagine the Sun as a bar magnet, with magnetic field lines cutting through it. The field lines are attached to the Sun.After a while, differential rotation stretches and stresses the field lines. Kinks develop.

• Solar Magnetic Field Line Twisting!Solar rotation causes magnetic field lines to become twisted and stretched to the breaking point. These eventually break and reconnect, creating heat, intense active regions, and solar blasts of charged particles.

• Stretching the Magnetic FieldThe magnetic field kinks appear on the surface as pairs of sunspots.The spots appear dark because they are cooler than their surroundings their energy is stored in the magnetic field.

• Images from NASA SOHOs EIT

• Prominences and FlaresEventually, something has to give. Just like a rubber band, the field lines will break and release their energy.Solar ProminenceSolar Flare

• Solar Flare from TRACE

• The Sun and EarthWhen the Sun has a lot of sunspots, solar flares, and prominencesThe earth is warmed by all the additional energyThe earth is bombarded with cosmic rays (i.e., high energy hydrogen and helium nuclei that are ejected from the Sun. (In other words, a stronger solar wind Stream of charged particles emitted from the sun.) The earths magnetic field and atmosphere protects us from these particles; those that get through are funneled into the atmosphere at the poles.

• Impact!Solar Flares can accelerate solar wind particles to nearly the speed of light

Can harm astronautsCan harm NASA Satellites

• Solar Wind

• Questions????

The sun was born out of a collapsing cloud of interstellar gas. As the infant sun forms, tangled magnetic fields act like magnetic brakes to slow-down the star's spinning. As a newly-born T-Tauri star, it spends the next 50 million years settling down to a more quiet state. (Courtesy: M.A. Garlick - NASA)