Coronal Holes: NASA image shows Sun ‘smiling’ down at us

Source: The post is based on the article “NASA image shows Sun ‘smiling’ down at us” published in Indian Express on 2nd November 2022.

What is the News?

NASA Solar Dynamics Observatory has shared an image of the sun seemingly ‘smiling’. NASA explained that the patches are called coronal holes which can be seen in ultraviolet light but are typically invisible to our eyes.

NASA has explained that these patches are called coronal holes which can be seen in ultraviolet light but are typically invisible to our eyes.

What are Coronal Holes?

Coronal Holes are regions on the sun’s surface from where fast solar wind gushes out into space.

Because they contain little solar material, they have lower temperatures and thus appear much darker than their surroundings. 

The holes are not a unique phenomenon, appearing throughout the sun’s approximately 11-year solar cycle.

Coronal holes can last between a few weeks to months. They can last much longer during solar minimum – a period of time when activity on the Sun is substantially diminished, according to NASA.

What do Coronal holes tell us?

These ‘coronal holes’ are important to understanding the space environment around the earth through which our technology and astronauts travel.

Scientists also study these coronal holes because they sometimes interact with earth’s magnetic field, creating what’s called a geomagnetic storm which can expose satellites to radiation and interfere with communications signals.

What is a Geomagnetic storm?

A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth. 

The largest storms that result from these conditions are associated with solar coronal mass ejections(CMEs) where a billion tons or so of plasma from the sun, with its embedded magnetic field, arrives at Earth. 

Geomagnetic storms can cause changes in the ionosphere, part of the earth’s upper atmosphere. Radio and GPS signals travel through this layer of the atmosphere and so communications can get disrupted.