U.S. #5600
2021 55¢ Sun Science – Solar Flare
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
Self-Adhesive
Quantity Printed: 18,000,000
Our Sun is the most powerful force in the solar system. It measures approximately 864,000 miles in diameter and is made up of intensely hot plasma. It is the light and heat given off by this plasma that makes life on Earth possible.
Even before humans understood what the Sun was, it was always recognized as extremely important. In fact, many early cultures worshipped it as a god. Later on, the predictability of the Sun's path gave rise to the development of history's first calendars. One of those calendars, the Gregorian, is what we continue to use to this day.
Scientists can't say for sure how the Sun was formed, but the most likely scenario is that it was triggered by a shockwave from a nearby supernova (exploding star). Scientists were able to make this hypothesis by analyzing the elements present within our solar system. Since supernova explosions generally scatter heavy elements like gold and uranium – present in high quantities in our solar system – that is most likely what sparked the formation of the Sun.
It's amazing to think about how much we've learned about the Sun throughout human history. Just imagine how many of its secrets we have yet to uncover!