This is for verification; students should recognize that they should not depend on a single source to draw a conclusion. This data is updated every minute. It is a good idea to obtain the data over several days prior to the day that students measured. NASA scientists use a variety of sources. They use solar and terrestrial instruments that gather data: from space and from the Earth's surface. Terrestrial data is acquired from an observatory whose main function is to monitor changes in the Earth's magnetic field.

Scientists use a graph called the Kp, planetary index, of the Earth's magnetic field which is calculated from data collected by 13 geomagnetic observations. For a complete explanation/activity of how to interpret and use observatory data go to: http://sunearth.gsfc.nasa.gov/sunearthday/2003/educators_guide2003/pdf/ssa_m.pdf