[Sunspot observation by Kris Larsen. Groups of sunspots are labeled]
It might surprise you to learn that the sun is actually variable star – it varies (albeit very slightly) in the amount of light that it sends earthward. The complex and ever-changing magnetic field of the sun creates both brighter than average (faculae) and dimmer than average (sunspots) regions on its visible “surface” (called the photosphere) that are continually changing in size and number. While a given sunspot group or faculae region may last for as little as a day or as long as two months, over a roughly 11-year period the numbers of these active regions waxes and wanes, creating the so-called sunspot cycle. Since the time of Galileo, observers have been monitoring sunspot activity. While this is a fun and scientifically useful activity, it must be done safely, as the sun is the only variable star that poses a danger to your eyesight if you aren’t careful. You should never look directly at the sun with your eyes or any optical equipment unless you are properly using an approved solar filter.
To this end, the Solar Section of the American Association of Variable Star Observers (which I am currently fortunate to serve as president) has recently released a Solar Observing Guide. Written by long-time AAVSO solar observer Frank Dempsey (with additional content by fellow Solar Section members and solar safety experts), this guide is a must for anyone contemplating solar observing. Anyone interesting in taking up this task should also seek the aid of a seasoned mentor to help them get started.
The sun changes every day, and safely observing these changes is an experience that will have you coming back again and again. But “safety first” is a must!
– Kris Larsen