The space climate is undergoing an extremely interesting phase – a 100-year period of heightened solar activity is coming to an end.
The sun and weather are the favourite topics of discussion every summer. Kalevi Mursula, professor of space physics at the University of Oulu is interested in both but his interest goes beyond the atmosphere. Mursula studies space climate, including radiation and particles in our solar system.
At the moment, the space climate is undergoing an extremely interesting phase.
The engine of the space climate is the sun, which exerts is influence on its environment by emitting light and releasing solar wind, a stream of charged particles. Now a 100-year period of heightened solar activity is coming to an end.
Keeping tabs on solar activity is important.
Increased solar activity refers to strong solar winds and electromagnetic eruptions called solar storms. When coming into contact with the Earth’s atmosphere, these eruptions may disrupt the functioning of electric devices and communication networks.
Last week, Helsingin Sanomat reported physicist Dr. Pete Riley’s calculations indicating that the likelihood of a disruptive solar storm over the next decade is 12 per cent.
“All our data on space particles are from the period of heightened solar activity. It’ll be interesting to see how the decrease in the activity affects the space climate.”
The task is made easier by the large quantity of data available to scientists as solar radiation is being monitored on dozens of wavelengths across the electromagnetic spectrum.
Researchers also gather additional information by observing the particle concentration in the near-Earth space.
Observing the past
But the Academy of Finland’s Centre of Excellence, the Research on Solar Long-term Variability and Effects (ReSoLVE) team, led by Mursula, is not satisfied with the current state of knowledge.
The scientists at the centre want to find out what has occurred in the sun’s activity over the past 150 years.
“We have both direct and indirect observations on solar activity available to us. For example, the number of sunspots have been observed for a long time.”
Information dating even further back can be gathered from drillings on ice caps, which contain isotopes that make it possible to draw conclusions on earlier changes in solar activity. These isotopes indicate that the sun was exceptionally active during the 20th century but periods of even greater activity took place thousands of years ago.
The reason behind the fluctuation in solar activity is not yet known. One hypothesis is that these long solar cycles are caused by the gravity forces of the planets in the solar system.
However, the current knowledge does not support this hypothesis.