U.S. #5604
2021 55¢ Sun Science – Sunspots
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
If you've heard of sunspots, you may wonder what they actually are. These spots are caused by areas of lower temperature on the Sun's surface. Since these cooler regions are not as bright as the surrounding areas, they appear as dark spots. (If it were possible to separate sunspots from the Sun's surface, they would shine brighter than the full moon.)
The first recorded sunspot observations were in China before 800 BC. Since then, scientists have found that the number, size, and location of sunspots vary throughout the Sun's 11-year solar cycle. They can be as small as 10 miles across or as wide as 100,000 miles. Some larger sunspots can even be seen without a telescope – though you still need to look through a solar filter to avoid damaging your eyes. Sunspots may last anywhere from a few days to several months.
Sunspots occur in areas of significant magnetic activity and are often seen in conjunction with other solar phenomena. This includes coronal loops, solar flares, and coronal mass ejections. Scientists are able to use the study of sunspots to better predict space weather caused by these corresponding events. Some of this weather can even impact Earth. For example, members of the amateur radio community love increased sunspot activity as it leads to increased radio range. It's amazing what our Sun can do from so far away!