NASA Spotlight: Details of the solar corona in today’s astronomical picture

The image featured by NASA on Tuesday (16) shows the solar corona, the structure of the Sun that would normally be hidden by the light of our star. To observe it, it is necessary to use instruments or, who knows, wait for a total solar eclipse like the one that occurred in April, when the picture was taken.

Pictured below is the result of a combination of short and long exposures of the eclipse, which was observed in Australia. Through digital manipulation techniques, the photographer was able to highlight the long, spreading structures of the crown, which can be seen during the phenomenon.

The procedure helped highlight some of the characteristics of the solar corona, such as its different layers, the brightness of the gases present and the magnetic fields. The rosette structures are solar outcrops, filaments of gas extending from the photosphere into the corona.

So-called Baily Grains also appear in the image – you’ll find them in the bright spots visible at the edge of the Sun’s disk. It is caused by the Moon: The Moon’s surface is irregular, and while it hides the Sun during an eclipse, it allows some of the light to shine through in some areas, forming bright spots.

What is the solar corona?

The corona is the outermost part of the sun’s atmosphere. It reaches about a million degrees Celsius, while the surface temperature of the sun is about 5500 degrees Celsius. Even at such a high temperature, the corona is dimly bright because it is about 10 million times less dense than the surface of the Sun.

In the corona, particles move at speeds high enough to escape the sun’s gravity and travel through space via the solar wind. When phenomena such as solar flares occur, a larger than normal amount of particles escape and interact with Earth’s atmosphere, affecting power grids and communication with satellites.

Because the Sun’s surface is so bright, the corona is often obscured from our view and cannot be seen without the appropriate instruments. That changes during a total solar eclipse, which occurs when the moon comes between the Earth and the sun, blocking the sun’s light.

source: APOD