Science Graphic of the Week: Zebra Stripes Discovered in Earth’s Radiation Belts
- 4:55 pm |
What’s neither black nor white but is radiating in a donut-shaped region of space around the Earth? The Van Allen belts, of course. And this week, scientists have discovered a new structure within these radiation belts, which they are calling ‘zebra stripes.’
The Van Allen belts, which extend high above our planet’s atmosphere, are made of high-energy protons and electrons emanating from the sun that have become trapped in the Earth’s magnetic field. The belts were discovered in the 1950s, but in 2012 NASA launched twin satellites called the Van Allen probes to study them in detail. In the course of their work, the satellites noticed a population of highly energetic electrons that are slanted relative to the rest of the belts. Because of their tilt, researchers thought they look like zebra stripes. The colorful graphic above shows the newly discovered structure’s banded pattern, making them look a bit more like those terrible Fruit Stripe chewing gum packs you bought as a kid when all the good flavors were sold out.
Most activity in the Van Allen belts is governed by the sun. When our local star is near the peak of its solar cycle and producing large amounts of activity, radiation levels in the belts can significantly increase (which sometimes becomes problematic for astronauts). When scientists first saw the zebra stripe pattern, they assumed it was in some way connected to the sun’s activity. Surprisingly, it’s not the sun but the Earth that is responsible for the Van Allen zebra stripes.
As it travels through the radiation belts, the Earth’s magnetic field generates a weak, oscillating electric field that permeates the inner parts the of the Van Allen belts. Our planet (and its magnetic field) are tilted, which explains the orientation of the zebra stripes. The changing electric field attracts groups of electrons, making them stretch and fold through the Van Allen belts like taffy. A video from NASA shows this taffy-like process occurring, resulting in the graphic above.