A total solar eclipse will cross over North America on Monday, April 8, 2024. As the moon crosses in front of the sun, the skies will darken and stars will become visible. Millions of Americans in the path of totality will be treated to this rare astronomical show; a partial eclipse will be visible across the contiguous United States.
Viewing an eclipse can be dangerous if you don't take proper precautions. The only safe way to look directly at the sun is through special-purpose solar filters, according to the National Aeronautics and Space Administration. These special filters are used in eclipse glasses and hand-held solar viewers. Eclipse glasses are available for purchase at big-box stores, electronics supply outlets and online; look for solar viewers that carry the certification insignia ISO 12312-2.
"The concern over improper viewing of the sun during an eclipse is for the development of 'eclipse blindness' or retinal burns," said associate professor of optometry Dr. Ralph Chou in an article published by NASA.
Chou said children and young adults are most at risk as the high level of visible and near-infrared radiation from the sun can cause heating and "cook" the exposed tissue of the eye. As there are no pain receptors in the retina, the damage might not be noticed for several hours.
Set Rules for Your Viewing Party
NASA outlines do's and don'ts of viewing the eclipse:
• Do not look directly at the sun
• Do not use homemade filters or ordinary sunglasses, even very dark sunglasses
• Use special solar filters, such as eclipse glasses or handheld solar viewers, to view the eclipse (beware of fakes!)
• Read and follow filter instructions and supervise children
• In any stage of eclipse, do not look at the sun through a camera, telescope, binoculars or other optical device, and never use solar filters with these devices, as concentrated solar rays will damage them and can cause serious eye injury
• Inspect your solar filter before use; if it is scratched or damaged, discard the filter
• Pinhole projection is a safe way to view the sun in indirect fashion; Exploratorium provides instruction on "How to Build a Sun Viewer" and other methods of safely viewing the sun
How Often Do Solar (or Lunar) Eclipses Occur?
The range is from four to seven eclipses each year, according to EarthSky.
• One calendar year has a minimum of four eclipses, two solar and two lunar
• The last time there were seven eclipses in a single year was 1982, and the next time will be 2038
• Few people see the shallow solar eclipses that occur regularly in the Arctic and Antarctic regions
Additional Resources
• American Academy of Ophthalmology
• American Astronomical Society
• NASA: Eye Safety During a Solar Eclipse
• EarthSky
• Exploratorium
