On Friday 9th October, we welcomed back Sam Walton to give us an update on the last talk he gave on Space Weather.  This time it was the Van Allan Radiation Belts OR “Gosh space is radioactive!”

He explained how the plasma from the sun in the form of mass coronal ejections or solar wind radiate from the sun and find their way to Earth.  It only takes 2 or 3 days to reach us and can cause damage to our satellites and affect our atmosphere

Diagrams were shown of the radiation belts where the Earth’s atmosphere acts as a deflection shield.  They showed two distinct belts – one inner and one outer.  The inner being much smaller than the outer.  They form a “doughnut” around the earth.  This doughnut contains magnetically trapped, high energy particles which were discovered by James Van Allan in 1958 after the launch of Explorer 1, the first US satellite.

Our current technology  is susceptible to these radiation particles.  As Sam explained they can upset instruments and electronics and it has become a pressing matter to understand and predict solar events.  He showed us where many of Earth’s satellites are in a geo-stationary orbit around the planet and how easy it would be for this radiation to disrupt  them.

It’s not just satellites.  The ISS could be affected.  As astronauts stay in orbit for longer, their radiation exposure may also increase, leading to concerns about long-term habitation for astronauts in space.

Sam likened some coronal mass ejections to a tsunami.   As with a tsunami triggered by an earthquake, so a CME can trigger a shock in specific areas of the radiation belts.

The talk was very informative and questions were asked which Sam was able to answer to members’ satisfaction.  He was thanked and asked if we would email him some feedback on the talk, which I was happy to do.


Marilyn Bentley