We have completed maintenance on DiscoverMagazine.com and action may be required on your account. Learn More

A Slinky That Lights the Sky

By Lauren Gravitz
Jun 1, 2003 5:00 AMNov 12, 2019 5:51 AM


Sign up for our email newsletter for the latest science news

NASA's Polar satellite has revealed one of the power sources behind the gossamer glow of the aurora: Alfvén waves, oscillations in Earth's magnetic field that resemble the quivering of a Slinky toy. John Wygant of the University of Minnesota and Andreas Keiling of the Center for Space Research on Radiation in Toulouse, France, used Polar's instruments to study energy flowing along the lines of the geomagnetic field. "Field lines have a certain tension. Charged particles are tied to those lines, so when the field wiggles around, they wiggle too," Wygant says. Magnetic waves moving along those lines can catch electrons and accelerate them to speeds up to 30,000 miles a second. Eventually the particles crash into air molecules, giving up their energy in the form of the green, blue, red, and violet light of the aurora. Wherever Keiling and Wygant detected a powerful electromagnetic wiggling, the associated field lines led down to a region of aurora. Polar's instruments also showed that the energy in each electron stream was proportional to the intensity of the display. Similar Alfvén waves may transport energy away from the surface of the sun, heating the solar atmosphere to millions of degrees.

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.