Solar particle event facts for kids
.gif)
A solar particle event (SPE) is a powerful burst of energy from the Sun. It's also called a solar radiation storm. These events happen when tiny particles, mostly protons, get super-fast. This can happen in the Sun's outer layers during a solar flare. Or it can happen in space when a coronal mass ejection (CME) creates a shock wave. Other particles, like helium, can also speed up. These fast-moving particles can reach Earth. They can even get through Earth's magnetic shield. This can partly change the ionosphere, a layer in our atmosphere. Strong protons are a danger to spacecraft and astronauts.
Contents
What Are Solar Particle Events?
SPEs happen when charged particles in the Sun's atmosphere speed up a lot. These fast particles are called solar energetic particles. They can escape into space. Once in space, they follow the Sun's magnetic field.
When these particles reach Earth, our planet's magnetic field guides them. They are pulled towards the North and South poles. There, they can enter Earth's upper atmosphere.
What Causes Solar Particle Events?
Scientists are still studying how these particles get so fast. But SPEs are usually put into two main groups.
Gradual Events
Gradual SPEs are thought to be caused by coronal mass ejections (CMEs). CMEs are huge bubbles of gas and magnetic field from the Sun. As they burst out, they create shock waves. These shock waves push particles to very high speeds. Gradual events are linked to certain radio signals from the Sun. They also have particles similar to the Sun's outer layer. These events create the strongest particle storms near Earth.
Impulsive Events
Impulsive SPEs are usually linked to solar flares. Solar flares are sudden, bright flashes on the Sun. During a flare, magnetic fields can reconnect. This process can speed up particles. Impulsive events are shorter and less intense near Earth. They are also linked to different types of radio signals.
Sometimes, an event can have features of both types. Scientists call these "hybrid" events.
How Do SPEs Affect Earth?
Most protons from SPEs do not have enough energy to get through Earth's magnetic field. But during very strong flares, protons can get super-fast. They can then reach Earth's magnetic field. They enter the atmosphere near the North Pole and South Pole.
Polar Cap Absorption Events
Fast protons that enter the polar regions hit air particles. They release their energy by causing ionization. Most of this energy goes into the D-region of the ionosphere. This is a layer about 50 to 80 kilometers high. This area is key for radio communications. It's where most radio signals are absorbed.
More ionization from these protons increases absorption. This can completely block radio communications in polar regions. These events are called polar cap absorption events. They start when incoming protons are strong enough. They last as long as the proton energy stays high.
These events cause problems for planes flying over the poles. Planes on polar routes often rely on high-frequency (HF) radio. If a polar cap absorption event is happening, planes must change their routes. This ensures they can still use HF radio.
Ground Level Enhancements
Some SPEs are extremely strong. They can produce protons with very high energy. These protons can create other particles when they hit the atmosphere. This can increase neutron levels on the ground. These rare events are called ground level enhancements (GLEs).
So far, 73 GLE events have been recorded. The strongest one ever was on February 23, 1956. Some events also produce other heavy particles. But protons are still the main radiation risk.
Dangers from Solar Particle Events
For Humans
Planes flying high over the poles have measured more radiation during SPEs. In 2019, new centers were set up. They give advice on space weather for international flights. This helps airlines know how to deal with space weather. Flights away from the polar regions are much safer from SPEs.
Astronauts outside Earth's magnetic field face a bigger risk. This includes astronauts traveling to the Moon or on its surface. But if astronauts are in low Earth orbit, they are safer. They can also stay in the most protected parts of their spacecraft. The closer a spacecraft gets to the poles, the more radiation it will get.
For Spacecraft
Fast protons from SPEs can electrically charge spacecraft. This can damage electronic parts. They can also make electronics act strangely. For example, a spacecraft's memory might change. This could lead to wrong commands being run.
Energetic proton storms also harm solar panels. Solar panels turn sunlight into electricity. Over years, spacecraft can lose a lot of power. This might mean important instruments have to be turned off.
When fast protons hit cameras on spacecraft, they cause flashes. This can make it hard to get clear images of the Sun or stars. In extreme events, spacecraft might even lose their way. This makes it hard for people on Earth to control them.
See also
- Heliophysics
- List of solar storms
- Solar energetic particles
- Space weather
