You are here:

Physics/Northern Lights

Advertisement


Question
Sir,

I watched a documentary on the Northern Lights and it said that some of the particles from the Solar Wind gets "trapped in Earth's magnetic field" and that the "bounce off" the poles several times a second and continue to oscillate between the North and South poles.

My question is..1) What causes them to bounce off the poles and 2) Where do they bounce off..the ice of the poles or in the air above the poles.
Finally 3) Do they stay there'..in their trapped state forever or do they get "liberated" at some point.

Thanks!

Answer
For 1) Forces from magnetic fields are perpendicular to the fields and the direction of motion.  As the field gathers at the poles, it causes forces on the spiraling particles which oppose their motion towards the poles.  It's kinda hard to explain without drawing it in a sketch...but you can envision that there are components of force perpendicular to the direction that they are traveling in if the magnetic field is coming in together. 2) They will bounce back and forth between poles in theory...but they will eventually lose energy to collisions with atoms in the very upper atmosphere.  That will cause their orbits in the magnetic field to get smaller and smaller until they just neutralize with their counterparts (electrons with positive ions and protons/etc with electrons) to become neutral atoms.

Physics

All Answers


Answers by Expert:


Ask Experts

Volunteer


Dr. Stephen O. Nelson

Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

©2016 About.com. All rights reserved.