Science topics Science topics

MagnetismMagnetism Sun spotsSun spots Solar flaresSolar flares Corona mass ejectionsCorona mass ejections

MagnetismMagnetism

Magnetism is the force where objects Magnetism is the force where objects are attracted or repelled to one another. are attracted or repelled to one another.

Magnets attract metals containing iron, Magnets attract metals containing iron, nickel, and/or cobalt but not most other nickel, and/or cobalt but not most other materialsmaterials

Magnets have two poles where Magnets have two poles where magnetic strength is most powerful. magnetic strength is most powerful.

http://www.youtube.com/watch?v=uj0DFDfQajwhttp://www.youtube.com/watch?v=uj0DFDfQajwhttp://www.youtube.com/watch?v=HQdLFEiVeCAhttp://www.youtube.com/watch?v=HQdLFEiVeCA

Magnetism and EMRMagnetism and EMR

Keep in mind electricity is just Keep in mind electricity is just another form of electromagnetic another form of electromagnetic radiationradiation

When a current (EMR) moves or When a current (EMR) moves or flows, it creates a magnetic fieldflows, it creates a magnetic field

Electric current is the source of Electric current is the source of magnetism.magnetism.

Electric current is charge in motion & Electric current is charge in motion & anywhere there is an electric current anywhere there is an electric current there is a magnetic force field there is a magnetic force field Anywhere there is charge there is an Anywhere there is charge there is an electric force field presentelectric force field present

If an object has no net electric If an object has no net electric current flowing through it, there will current flowing through it, there will be no magnetic fieldbe no magnetic field

MagnetismMagnetism

Bar Magnet with magnetic compasses placed around it. Note how the heads of the compass needles point toward the magnetic south pole and away from the magnetic north pole of the Bar Magnet.

(http://cse.ssl.berkeley.edu/SegwayEd/lessons/exploring_magnetism/Exploring_Magnetism/Exploring_Magnetism.pdf)

Magnetic Field line tracing of a bar magnet with a dipole magnetic field using compasses.

Jump Rope GeneratorJump Rope Generator

Jump Rope Generator worksheetJump Rope Generator worksheet

SunspotsSunspots Sunspots are places where strong Sunspots are places where strong

loops of the Sun’s magnetic fields loops of the Sun’s magnetic fields poke through the Sun’s surface poke through the Sun’s surface

The magnetic fields trap plasma The magnetic fields trap plasma inside and do not allow it outside the inside and do not allow it outside the loops, causing the area to be cooler loops, causing the area to be cooler than average on the photosphere than average on the photosphere and makes sunspots appear darker. and makes sunspots appear darker.

Scientists have found that Scientists have found that sunspots sunspots are like magnetic poles of a bar are like magnetic poles of a bar magnet. Draw what you predict the magnetic field above the surface of magnet. Draw what you predict the magnetic field above the surface of

the Sun looks like in the region around the sunspots. the Sun looks like in the region around the sunspots.

Scientists have found that sunspots are like magnetic poles of a bar Scientists have found that sunspots are like magnetic poles of a bar magnet. Draw what you predict the magnetic field above the surface of magnet. Draw what you predict the magnetic field above the surface of

the Sun looks like in the region around the sunspots. the Sun looks like in the region around the sunspots.

Sunspots and Coronal LoopsSunspots and Coronal Loops

Above the sunspots, the magnetic Above the sunspots, the magnetic field loop also traps hot plasmas = field loop also traps hot plasmas = coronal loops. coronal loops.

SunspotsSunspots

Sunspots drift in position relative to one Sunspots drift in position relative to one another on the photosphere because of another on the photosphere because of convection beneath the photosphere plus convection beneath the photosphere plus the differential rotation of the Sun. the differential rotation of the Sun.

These motions distort the sunspots’ These motions distort the sunspots’ magnetic fields and cause them to twist up magnetic fields and cause them to twist up and become more and more complicated and become more and more complicated in shape. in shape.

The more complicated the magnetic fields The more complicated the magnetic fields shape become, the more energy they storeshape become, the more energy they store

PhotospherePhotosphere Visible surface of the Sun about Visible surface of the Sun about

100 km thick 100 km thick Sun rotates on its axis once in Sun rotates on its axis once in

about 27 days - equatorial about 27 days - equatorial regions rotate faster (about 24 regions rotate faster (about 24 days) than the polar regions days) than the polar regions (rotate once in <30 days). (rotate once in <30 days).

The Sun's rotation axis is tilted The Sun's rotation axis is tilted by about 7.25 degrees from the by about 7.25 degrees from the axis of the Earth's orbit so we axis of the Earth's orbit so we see more of the Sun's north pole see more of the Sun's north pole in September of each year and in September of each year and more of its south pole in March.more of its south pole in March.

http://solarscience.msfc.nasa.gov/images/sunturn.gif

Solar FlaresSolar Flares

Sudden, rapid, and intense increases Sudden, rapid, and intense increases in brightness in relatively small in brightness in relatively small regions in the Sun’s atmosphereregions in the Sun’s atmosphere

Solar flares occur when magnetic Solar flares occur when magnetic fields in the Sun’s atmosphere fields in the Sun’s atmosphere rapidly change shape and generate rapidly change shape and generate currents of electrically charged currents of electrically charged plasmas. plasmas.

Solar FlaresSolar Flares

The energy released by flares takes The energy released by flares takes the form of light, heat, and the the form of light, heat, and the movement of large amounts of movement of large amounts of plasma. plasma.

Light from across the entire Light from across the entire electromagnetic spectrum, from electromagnetic spectrum, from radio waves to gamma rays, can be radio waves to gamma rays, can be generated in the biggest flares. generated in the biggest flares.

Solar Flares and CME’sSolar Flares and CME’s

Some flares also seem to generate Some flares also seem to generate gigantic eruptions of matter that are gigantic eruptions of matter that are ejected out into interplanetary space ejected out into interplanetary space = Coronal Mass Ejections (or CME for = Coronal Mass Ejections (or CME for short). short).

Solar Flares and EMRSolar Flares and EMR

Light is also produced in solar flares. Light is also produced in solar flares. • Plasma consists of charged particles Plasma consists of charged particles • Plasma moves through magnetic field Plasma moves through magnetic field

associated with the sunassociated with the sun• When charged particles move through a When charged particles move through a

magnetic field they do not follow magnetic field they do not follow straight paths but spiral around. This straight paths but spiral around. This spiraling motion is an acceleration that spiraling motion is an acceleration that causes the charged particles to radiate causes the charged particles to radiate light light

Coronal mass ejectionsCoronal mass ejections Powerful eruptions that can blow up Powerful eruptions that can blow up

to 10 billion tons of the Sun's to 10 billion tons of the Sun's atmosphere into interplanetary atmosphere into interplanetary space.space.

Traveling away from the Sun at Traveling away from the Sun at speeds of approximately one million speeds of approximately one million mph (1.6 million kph), CMEs can mph (1.6 million kph), CMEs can create major disturbances in the create major disturbances in the interplanetary medium and trigger interplanetary medium and trigger severe magnetic storms when they severe magnetic storms when they collide with Earth's magnetosphere.collide with Earth's magnetosphere.

CME’sCME’s Large geomagnetic storms directed Large geomagnetic storms directed

towards Earth can damage and even towards Earth can damage and even destroy satellites, are extremely destroy satellites, are extremely hazardous to Astronauts when hazardous to Astronauts when outside of the protection of the outside of the protection of the Space Shuttle performing Extra Space Shuttle performing Extra Vehicular Activities (EVAs), and they Vehicular Activities (EVAs), and they have been known to cause electrical have been known to cause electrical power outages.power outages.

Space WeatherSpace Weather Solar storm from the Sun travels through Solar storm from the Sun travels through

space and impacts the Earth’s space and impacts the Earth’s magnetosphere.  magnetosphere. 

Studying space weather is important to our Studying space weather is important to our national economy because solar storms can national economy because solar storms can affect the advanced technology we have affect the advanced technology we have become so dependent uponbecome so dependent upon

Space WeatherSpace Weather Energy and radiation from solar flares and Energy and radiation from solar flares and

coronal mass ejections can:coronal mass ejections can:• Harm astronauts in space Harm astronauts in space • Damage sensitive electronics on orbiting Damage sensitive electronics on orbiting

spacecraft… spacecraft… • Cause colorful auroras, often seen in the Cause colorful auroras, often seen in the

higher latitudes… higher latitudes… • Create blackouts on Earth when they Create blackouts on Earth when they

cause surges in power grids. cause surges in power grids.

Solar WindSolar Wind

The solar wind speed is not uniformThe solar wind speed is not uniform Always directed away from the SunAlways directed away from the Sun Solar wind speed is 800 km/s over Solar wind speed is 800 km/s over

coronal holes and low (300 km/s) over coronal holes and low (300 km/s) over streamers. streamers.

High and low speed streams interact High and low speed streams interact with each other and pass by the Earth with each other and pass by the Earth as the Sun rotates and can produce as the Sun rotates and can produce storms in the Earth's magnetosphere.storms in the Earth's magnetosphere.

Solar windSolar wind

The solar wind consists of particles, The solar wind consists of particles, ionized atoms from the solar corona, ionized atoms from the solar corona, and fields, in particular magnetic and fields, in particular magnetic fields.fields.

As the Sun rotates the magnetic field As the Sun rotates the magnetic field transported by the solar wind gets transported by the solar wind gets wrapped into a spiralwrapped into a spiral

Variations in the Sun's magnetic field Variations in the Sun's magnetic field are carried outward by the solar windare carried outward by the solar wind

Solar windSolar wind

Solar wind streams off of the Sun in all Solar wind streams off of the Sun in all directions at speeds of about 400 km/s directions at speeds of about 400 km/s (about 1 million miles per hour). (about 1 million miles per hour).

Source of the solar wind is the Sun's Source of the solar wind is the Sun's corona where the temperature is so high corona where the temperature is so high that the Sun's gravity cannot hold on to it.that the Sun's gravity cannot hold on to it.

We do not understand the details about We do not understand the details about how and where the coronal gases are how and where the coronal gases are accelerated to these high velocities. accelerated to these high velocities.

MagnetosphereMagnetosphere

Solar wind and its magnet field, is Solar wind and its magnet field, is strong enough to interact with the strong enough to interact with the planets and their magnetic fields to planets and their magnetic fields to shape shape magnetospheresmagnetospheres

A magnetosphere is the region A magnetosphere is the region surrounding a planet where the surrounding a planet where the planet's magnetic field dominatesplanet's magnetic field dominates

Magnetosphere protects life on Magnetosphere protects life on EarthEarth

Because ions in the solar plasma Because ions in the solar plasma (wind)are charged(wind)are charged• They interact with these magnetic fieldsThey interact with these magnetic fields• Solar wind particles are swept around Solar wind particles are swept around

planetary magnetospheres. planetary magnetospheres. • Life on Earth has developed under the Life on Earth has developed under the

protection of this magnetosphere. protection of this magnetosphere.

Shape of Earth’s Shape of Earth’s MagnetosphereMagnetosphere

Solar wind compresses its Solar wind compresses its sunward side to a distance of sunward side to a distance of 6 to 10 times the radius of the 6 to 10 times the radius of the Earth. Earth.

A shock wave is created A shock wave is created sunward of Earth like a sonic sunward of Earth like a sonic boom – called the boom – called the bow shockbow shock. .

Most of the solar wind Most of the solar wind particles are heated and particles are heated and slowed at the bow shock and slowed at the bow shock and detour around the Earth. detour around the Earth.

Solar wind drags out the Solar wind drags out the night-side magnetosphere to night-side magnetosphere to possibly 1000 times Earth's possibly 1000 times Earth's radius (exact length unknow) radius (exact length unknow)

This extension of the This extension of the magnetosphere is known as magnetosphere is known as the the magnetotailmagnetotail. Many other . Many other planets in our solar system planets in our solar system have magnetospheres of have magnetospheres of similar, solar wind-influenced similar, solar wind-influenced shapes.shapes.

Earth’s MagnetosphereEarth’s Magnetosphere

Magnetosphere is dynamic and Magnetosphere is dynamic and fluctuates with timefluctuates with time

http://pixie.spasci.com/DynMod/movie20000714.gifhttp://pixie.spasci.com/DynMod/movie20000714.gif

Magnetism in spaceMagnetism in space

In space there is no magnetic iron, yet In space there is no magnetic iron, yet magnetism is widespread. magnetism is widespread.

Sunspots consist of glowing hot gas, Sunspots consist of glowing hot gas, yet they are all intensely magnetic. yet they are all intensely magnetic.

The Earth's own magnetic powers The Earth's own magnetic powers arise deep in its interior, and arise deep in its interior, and temperatures there are too high for temperatures there are too high for iron magnetsiron magnets

It is all related to electricityIt is all related to electricity

Remember: anywhere there is an Remember: anywhere there is an electric current there is a magnetic electric current there is a magnetic force field and anywhere there is force field and anywhere there is charge there is an electric force field charge there is an electric force field presentpresent

So movement of sunspots with So movement of sunspots with plasma and CME’s will pass through plasma and CME’s will pass through magnetic fields and produce electric magnetic fields and produce electric fields fields

On the left, a model of the magnetic field (spiral lines) of the Sun (in the middle) is shown as one looks down on the Sun’s axis of rotation. This magnetic field is known as the interplanetary magnetic field (IMF). The orbits of Mercury, Venus, and Earth are shown as circles. The spiral of the IMF shown here is due to the fact that the IMF is attached to the rotating Sun, but we draw it from a non-rotating perspective from above.