The Earth’s magnetosphere helps protect us from high-energy particles from the Sun. Occasionally, these particles get through the magnetosphere and cause problems with electronics on Earth as well as create dangerous situations for satellites and astronauts. It is commonly referred to as space weather and in order to get new information scientists have sought out an unlikely source. They are looking at declassified data from cold war nuclear testing.
From 1958-1962 the US and the USSR conducted high-altitude nuclear tests to see how these weapons worked in the upper atmosphere. The results were similar to known space weather events, just on a smaller scale. The blasts created large amounts of expanding plasma that distorted Earth’s magnetic field lines. Charged particles created from the blasts remained for a number of weeks to years. At least one of these tests was so powerful that it caused an aurora to appear in the sky near the equator.
By studying the information collected in these tests scientists can learn more about how they affected the magnetosphere and man-made objects like satellites. The only other way to collect data is to watch the Sun and wait for something to happen.
The infographic below has more details on the tests.