On April 8, a total solar eclipse will cross North America. For millennia, solar eclipses have fueled the imagination of cultures around the world, inspiring myths, legends, and even fear. Ancient civilizations interpreted these events as omens, often associating them with the wrath of the gods or impending doom. Even today there is a viral TikTok video post claiming the April eclipse is sign of the end of the world. Nevertheless, as science advanced, so did our understanding of these phenomena. Today, solar eclipses serve as invaluable research opportunities, allowing scientists a chance to study the Sun's corona, the outer layer of its atmosphere, which is typically obscured by its brilliance. For non-scientists they are a rare occasion to experience the wonder and beauty of the universe.
A total eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. What is visible during a total eclipse depends on the location. Only in the area known as the “path of totality” will the Moon’s shadow completely cover the sun. When this happens, the sky darkens as if it were twilight, and often birds cease their chirping and the temperature cools significantly. Lengths of the period of totality vary from eclipse to eclipse. This year it will be about four minutes with a maximum length of totality of 4:28. The overall length of the eclipse will be about two and half hours. You can use NASA's Eclipse Explorer to follow the progress.
There are several stages that occur during an eclipse. The first state is the partial eclipse during which the Sun appears to have a crescent shape as the Moon passes between it and the Earth. Just before totality, shadow bands - wavy, dark lines - may appear on the ground or buildings. These are caused by particles in the Earth’s upper atmosphere. Next is a short phase when the Sun’s rays stream through the valley’s along the Moon’s horizon causing bright spots known as Baily’s Beads. As these disappear, eventually only a single bright spot remains along the edge of the Moon’s shadow. This is known as the diamond ring effect. Finally, the eclipse reaches totality when there is no longer any direct sunlight. During totality, observers might glimpse the Sun’s chromosphere, characterized by a thin pink circle surrounding the Moon, and the corona, which presents as radiant white streams extending from the Sun's outer atmosphere. After totality the phases repeat in the opposite order.
Safety is key when viewing an eclipse. Solar viewing glasses can protect the eyes when looking directly at the sun. Indirect methods such as pinhole projectors create an image of the Sun on a surface where you can safely see the progress of the eclipse. Solar filters are needed for telescopes and binoculars. All these options will be available at the Library’s Eclipse Viewing Party on April 8 between 12:48 and 3:18pm on the MARC lawn. Dubuque is not on the path of totality but is relatively close so we should see some significant changes if the weather is good. Don’t miss this chance. The next total solar eclipse that can be seen from the contiguous United States won't be until August 23, 2044!
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