Data

The aurora can wrap all the way around Earth's polar regions, and it can exhibit remarkable changes in its geometry and brightness. This image was gained from Professor Frank's camera on board the Polar spacecraft.	Imagine what it would be like if molecules of air suddenly got together and decided to start whistling, all by themselves. It doesn't happen in a simple gas, but it does happen in space. This is a spectrogram of radio and plasma waves, from Professor Gurnett's instrument on Cassini when it flew by Earth in 1999. The vertical axis is frequency, the horizontal axis is time.	Electrons which cause the aurora are shown in this spectrogram of electron energy, from Professor Kletzing's sounding rocket experiments.
Radio waves in Earth's ionosphere are produced by the same mechanisms that are responsible for the aurora. Professor Mutel's group uses data from Cluster to calculate where this noise originates, as shown by the red dots. They use the four spacecraft as if they were four radio telescopes, and triangulate the source of the radio waves.	Map of the pressure of electrons in the Earth's magnetosphere, as compared to the magnetic field pressure, from Professor Scudder's instrument on Polar. The 40 km X 40 km region shown here is tiny by the standards of space physics, but what is even tinier is the intense spot at the center, called an X-point, which is like a highway interchange where electrons change directions.

Last updated July 28, 2003. © The University of Iowa 2003. All rights reserved. Contact information. Send questions or comments to the webmaster. The Department of Physics and Astronomy is a part of the College of Liberal Arts & Sciences.