Magnetism and the Sun NEIU 19 ~ NASA Endeavour 5 March 2008

What do you know about Magnetism???

Seeing Magnetism Please observe and respond to the following questions 1)What is happening that is impacting the speed and direction of the iron filings? 2)What did you observe about iron filings near the bar magnet? 3)Why do you think that this happened?

Magnetism Force of Nature All atoms are magnetic  meaning that they have charges moving within them –For an object to act as a MAGNET, the magnetic fields within it (charged particles) must align with one another –In order to line up, the charged particles must be able to move freely

Charged Particles External 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) each Like 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 mass Electric force arises from Charge: two kinds of charge (positive and negative), like charges repel and opposite charges attract Gravitational field of a point of mass Electric field of 2 opposite charges Electric field of 2 like charges

Describing the Earth’s Magnetic Field Introducing Magnetic Field Lines !!!Magnetic Field Lines

Magnetic Field Magnetic field of a Bar Magnet: 2 poles, called North and South Dipole field Field has direction: lines point away from N and toward S Definition of a Pole: Where lines meet (converge) e.g.: lines of longitude on a globe meet at poles

Moving molten iron in Earth’s outer core causes most of Earth’s 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

Earth’s Magnetic Field

The Sun’s Differential Rotation The 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 Sun’s Magnetic Field? Follow the North/South Field Lines What begins to happen?

The Sun’s Magnetic Field Imagine 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 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 Field The 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 SOHO’s EIT

Prominences and Flares Eventually, something has to give. Just like a rubber band, the field lines will break and release their energy. Solar Prominence Solar Flare

Solar Flare from TRACE

The Sun and Earth When the Sun has a lot of sunspots, solar flares, and prominences  The earth is warmed by all the additional energy  The 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 earth’s 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 astronauts Can harm NASA Satellites

Solar Wind

Questions????