Van Allen belts contain high energy electrons and protons, but what about the area between the belts?

Is it "regular" space, just like it is past the belts? Anything interesting going on there? "Just" exosphere?

I suspect that it is more protected by the Earth's magnetic field than the space past the belts -- when compared to the side facing the sun, correct?

Google searches for "between Van Allen belts" and similar don't come up with much useful data.

  • $\begingroup$ The wikipedia article on the belts has plots of proton flux that should give you a rough idea of how much radiation is between the belts. $\endgroup$ Mar 31, 2016 at 6:39
  • $\begingroup$ Everything above ~50-80 km starts to become ionized and the ionization fraction increases exponentially with altitude. By a few 100 km the gas is basically 100% ionized. This plasma extends out into space and the region of high density surrounding Earth is called the plasmasphere (typically extends to ~4-6 Earth radii). The radiation belts are just high energy particles on trapped trajectories, all other space is mostly low energy particles. $\endgroup$ Jan 19, 2021 at 23:26

1 Answer 1


I simulated a highly elliptical orbit in SPENVIS with a low inclination of 8 degrees, that went past the outer belt.

Orbit in fixed reference system

Altitude vs time

Judging by the graphs created in SPENVIS (AP-8 and AE-8 models with maximum solar activity) and the link in 2012crampion's comment, the area between the belts still has a relatively high electron and proton flux, just a few orders of magnitude lower, but much higher than outside of the belts proper.

Electron flux vs time

Proton flux vs time

Also, Earth's magnetic field seems pretty strong, so my guess is that the area doesn't see much cosmic rays and solar particles, compared to the apogee.

Magnetic field vs time

  • 1
    $\begingroup$ Where in those plots are the belts? $\endgroup$
    – Hobbes
    Apr 5, 2016 at 17:39
  • $\begingroup$ In the altitude v orbital time plot we can see which orbital hours are spent on the heights that correspond to the belts. Then we use those hours as the reference for other plots. Altitudes of the belts should be looked up on Wikipedia as an exercise to the reader :D $\endgroup$
    – Alfis
    Apr 5, 2016 at 19:19

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