June 9, 2017

By: André Gradvohl, IEEE Senior Member and Assistant Professor at University of Campinas

We all know that the Sun is one of the main sources of heat for the Earth. What most of us do not know is that many phenomena occurring in the Sun have an impact on strategic services on Earth. It affects telecommunications, power transmission and even some flight routes that cross the poles. We call this Space Weather, the repercussion of solar phenomena on our planet. The effects of Space Weather are mitigated so they do not affect our day to day life.

The Sun produces its energy through the nuclear fusion of hydrogen nuclei into helium. This activity generates light, radiation, and plasma, as well as a very strong magnetic field. The solar magnetic field keeps changing all the time and these changes cause the Space Weather. Among the main phenomena that occur in the Sun and reach the Earth are sunspots, solar explosions, and coronal mass ejections or CMEs.

One of the results of solar activity is sunspots. These spots appear in the solar photosphere – the visible part of the Sun – as dark spots, since they are areas with a lower temperature than the rest of the photosphere. In addition to being darker, they have associated magnetic fields.

When two sunspots with opposing magnetic fields approach, they create magnetic arcs. These arcs can rupture and, when this happens, a solar explosion occurs. One of the effects of this explosion is the emission of X-rays.

There are five classes of X-ray explosions:

  1. Classes A and B are very weak.
  2. Class C is intermediate and has little repercussions on Earth.
  3. Class M explosions already have some consequences, such as brief blackouts of radio transmissions at the poles of the Earth.
  4. Class X explosions can cause radiation storms and radio blackouts on a global scale.

In some of these explosions, in addition to X-ray emissions, there may be coronal mass ejections (CME). The coronal mass is formed mainly by protons and electrons, which are ejected at very high speed. They travel around 500 to 1000 kilometers per second.

When it arrives on Earth, the CME causes the Aurora Borealis (in the North Pole) and the aurora Australis (in the South Pole). However, depending on its volume, the CME compresses the terrestrial magnetosphere and ionosphere, two invisible layers – one magnetic and other electron formed – that protect the Earth. When these layers are compressed, problems occur in GPSs and in high-frequency radio transmissions. They can also cause problems for satellites, astronauts, or other equipment in orbit.

Therefore, just like the Earth’s weather, we also need techniques to predict the effects of the Space Weather. There are centers in Brazil and around the world dedicated to making these predictions. The next step in the research is to forecast these predictions automatically. For this, we are already studying methods of data mining and Big Data to predict these phenomena as far in advance as possible.


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