In this post, it is explained the coronal mass ejection phenomena and its interaction with Earth`s magnetosphere.
What is it and how it is formed?
It is a plasma cloud with a magnetic field ejected from Sun. Usually occurs together with solar flares in regions whose magnetic field is very strong. Just like the solar flares, also are formed when magnetic fields are twisted and realigned by magnetic reconnection.
To know about solar flares, click in the button below.
A coronal mass ejection can travel through space with speed between 250 km/s (kilometers per second) and 3000 km/s. The slower coronal mass ejections can take days to reach Earth. While the faster take from 14 to 17 hours.
The coronograph
This instrument serves to observe the ejections and see your parameters: size, speed, direction, and density. Allows the observation of the chromosphere and outer corona blocking the solar disk`s light, like a lunar eclipse.
The coronograph is a telescope with a circular bulkhead which blocks the solar disk and has an H-α filter. In Earth, must be used in high altitudes and very clear days to minimize light diffusion.
The coronograph can be installed in spacecrafts like the Soho to study the Sun.
Forming auroras
When a coronal mass ejection hits Earth`s magnetosphere, electrons from coronal mass colide with air molecules, the later absorb energy and then emit in form of light.
In the northern hemisphere is called northern lights and in southern hemisphere, southern lights. The aurora`s color depends on the element of atom which absorbs the electron and altitude
- Pink color: altitude below 90 km and nitrogen gas (N_{2}).
- Red color: altitude above 300 km and oxygen atoms.
- Blue or purple: altitude between 200 and 300 km and N_{2}.
- Green: oxygen or nitrogen and altitude between 100 and 200 km.
When appears and how affect the technologies?
The coronal mass ejection is more dangerous than solar flares. If the ejection is strong enough, can generate geomagnetic storms which can damage electronic parts of satellites and wireless communication systems with energetic particles. Can melt copper winding of transformers, damaging electric energy supply network.
The ejections follow a solar cycle, the number of sunspots increases in average each 11 years, can vary from 8 to 15 years. A bigger number of sunspots indicate higher probability to occur a coronal mass ejection.
