Earth’s Magnetic Field
The Earth’s magnetic field, like a bar magnet, has a north and a south magnetic pole, with magnetic lines of force resembling meridians of longitude in that the magnetic lines of force come out of one pole and follow the curve of the Earth toward the other pole. Each magnetic pole is at a location where the magnetic lines of force converge and are vertical. This point on the Earth’s surface is also known as the dip pole, as this is the one location in each hemisphere where a compass needle, if designed to swing in all directions, would point straight down with a dip angle of 90º. Interestingly, neither magnetic pole is at the same location as its corresponding geographic pole. For example, the current location of the north magnetic pole is at approximately 81.3º N, 110.8º W. The word current has to be used because the location of the magnetic poles changes constantly due to variations in the processes that create the Earth’s magnetic field.
There is an interesting history behind the search for the magnetic pole and you could learn about the migrating magnetic pole and practice mapping and geographic skills by using the teacher-created activity Motion of the Magnetic Pole (see Internet Resources below). This is one of many lessons and activities developed by a cadre of teachers participating in POETRY, the education outreach of NASA’s IMAGE (Imager for Magnetopause- to-Aurora Global Exploration) mission. The IMAGE mission was a six-year mission ending in 2005 that focused on a study of the Earth’s magnetosphere by imaging the magnetosphere in non visible wavelengths. Use the POETRY website (see Internet Resources below) to find lessons and activities written by classroom teachers for all grade levels.
Magnetic effects in space—http://archive.org/details/skylab_magnetic_effects
Magnetic field calculators—www.ngdc.noaa.gov/geomag- web/#declination
The Magnetic Sun—http://solar.physics.montana.edu/ypop/Spotlight/Magnetic
Motion of the magnetic pole—http://image.gsfc.nasa.gov/poetry/activity/s8.htm
Planetary magnetic fields PowerPoint—http://education.gsfc.nasa.gov/nycri/units/pmarchase/3b-magnetic_field.ppt
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.