“Coronal holes” Phenomenon on the Sun

November 2, 2022

An image of coronal holes was shared by NASA recently.

What are coronal holes?

Coronal holes are regions on the Sun’s surface where the fast solar winds are spurted out into the outer space. Since they have little solar material, they have lower temperature. Therefore, they appear much darker than their surrounding regions. In these dark regions, magnetic field is open to interplanetary space, sending solar material in a high-speed stream of solar winds.
The cause of the coronal holes is unknown. They can last between several weeks to months. This common phenomenon occurs throughout the solar cycle that lasts for over 11 years. Coronal holes can last longer during the solar minimum – a period when the Sun’s activity is significantly low.

What does coronal hole’s presence indicate?

Coronal holes are critical for understanding the space environment surrounding the Earth, where space technologies and astronauts travel. This is because, they correlate to areas on the Sun where magnetic fields are pushed up and into the outer space instead of looping back down to the surface like they do elsewhere. Scientists monitor and research the fast moving solar wind streams from the coronal holes since they sometimes interact with the Earth’s magnetic field and create geomagnetic storm.

How does the geomagnetic storm impact the Earth?

Geomagnetic storms are related to the Earth’s magnetosphere – a space around the planet that is influenced by its magnetic field. During certain situations, a high-speed solar stream reaches the Earth via the magnetosphere and hit the atmosphere over the poles. This disturbs the magnetosphere since there is a very efficient exchange of energy from the solar wind in the space environment around the Earth. In certain circumstances, geomagnetic storm can cause changes in the ionosphere. This disrupts radio and GPs signals that travel through ionosphere and affect communications.

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