Magnetosphere (magnetic field). Convection of liquid metals in the outer core creates the Earth's magnetic field. Extends outward from the Earth for several thousand kilometers - PowerPoint PPT Presentation
Magnetosphere (magnetic field)Convection of liquid metals in the outer core creates the Earth's magnetic field. Extends outward from the Earth for several thousand kilometersDeflects the Sun's solar wind. Without this field, the solar wind would directly strike the Earth's atmosphere. This could potentially have removed the Earth's atmosphere, rendering it nearly lifeless, as is hypothesized for Mars.
Earths Magnetic FieldEarth is a giant dipole magnetMagnetic poles are very close to the geographic poles May result from different rotation speeds of outer core and mantle
2Polar WanderingThe apparent movement was called polar wandering. The best explanation for this movement is that the poles are stationary, and the continents moved.
In the 1950s, research showed that the poles had been in differentpositions in the past.3Polar Wandering* Further evidence for plate tectonics
Misnomer - The magnetic poles havent moved.the plates have moved.
Magnetic ReversalsEarths present magnetic field is called normal. Magnetic north is near geographic north.
At various times in the past, Earths magnetic field has completely reversed, with magnetic south near the north geographic pole. This is referred to as a magnetic reversal.5Magnetic ReveralsNorth magnetic pole switches with South magnetic pole4-5 during the last 10 myNo idea when it will flip againMagnetic ReversalsMeasuring paleomagnetism and dating continental lava flows led to the realization that magnetic reversals existedthe establishment of a magnetic reversal time scale
7Dynamo Theory:- Rapid Rotation- Metal (electrical conductor)magnetic field generation requires:What makes the Earth a magnet?- Liquid Core
Will a compass lead youdirectly to the geographicNorth Pole???
Van Allen Belts - Two regions surrounding Earth that capture high-energy charged particles
Particles originate in solar wind
a) outer belt - contains mostlylighter electronsb) inner belt contains heavierprotons
Wed die in the Van Allen Belts
Charged particles escape Van Allen belts near the North and South magnetic polesCharged particles then collide with air molecules, get excited, then=> Produce spectacularlight show called AURORA