2021 55¢ Sun Science – Coronal Loops
Value: 55¢ 1-ounce First-class rate (Forever)
Issue Date: June 18, 2021
First Day City: Greenbelt, MD
Type of Stamp: Commemorative
Printed by: Banknote Corporation of America
Printing Method: Flexographic, Foil Stamping
Format: Pane of 20
Quantity Printed: 18,000,000
The Sun is made up of a number of different parts. Perhaps one of the most well known is the corona. This word is Latin for "crown" and refers to the layer of plasma that surrounds the Sun. (You may have heard of it in relation to total solar eclipses – the best time to view the corona.)
Scientists have measured the Sun's corona as extending hundreds of thousands of miles into space. They've also estimated temperatures of over one million degrees kelvin. That's more than 1.8 million degrees Fahrenheit. Interestingly, this makes the Sun's corona hotter than its surface. To give some perspective on what this means for our solar system, let's take a look at Mercury. This tiny planet is 35 million miles away from the sun and still experiences temperatures of up to 800 degrees Fahrenheit during the day!
Much about the Sun's corona is still a subject of mystery for scientists. However, we do know that the far edges of the corona are pulled away from the Sun by something called magnetic flux. This generates solar wind, which can sometimes reach Earth. Thankfully, our atmosphere protects us from the harmful effects of this intense solar radiation. We do, however, get something positive from this radiation – the beautiful aurora events that take place at Earth's North and South Poles.