2021 55¢ Sun Science – Coronal Hole
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
Our Sun is classified as a G-type main-sequence star, also known as a red-orange-yellow star. Many stars in this category are the same size as our Sun, though there are also smaller and larger examples. Regardless of size, G-type main-sequence stars have surface temperatures that fluctuate from 5,300 to 6,000 degrees kelvin. That's equal to about 9,000 to 10,000 degrees Fahrenheit!
All the heat and energy produced by G-type main-sequence stars are created by the same reaction. Deep inside the core of these stars, nuclear fusion is taking place. In this reaction, hydrogen atoms are forced together to form new helium atoms. Our Sun completes this reaction at an astounding rate – about 600 million tons of hydrogen is transformed into helium every second. Four million tons of matter is converted into energy during this process.
Nuclear reactors on Earth create energy through the opposite process – fission, which splits atoms instead of joining them. While this still creates a huge amount of energy, it is nowhere near the amount produced by nuclear fusion. However, because of the massive cost of creating a productive nuclear fusion reactor, scientists have not yet been able to make this dream a reality. It puts into perspective just how valuable the power from our sun really is.