The Best Optical Filters for Solar Observation

Solar cycles are measured by the ebb and flow of naturally occurring sun spots. These spots appear as dark cooler spots. As Solar Cycle 24 progresses towards its minimum solar activity with over 100 days of displaying zero sunspots, astronomers and solar researchers alike, look forward to the sun “waking up” and ushering in Solar Cycle 25. Solar cycles have an average 11-year life span. During this new 11-year cycle we can expect to start seeing a heightened number of sunspots and solar events in the upcoming years. Activity should peak around the year 2025. This paper is intended to illustrate the variety of optical filters available for viewing solar activity and how they can improve the precision and value of the data collected.

Astronomers can choose to study the sun across a broad spectrum (e.g.; visible “white” light, or infrared) or choose among several narrow band wavelengths, H-Alpha and CaK, being the most prominent.