The Great American Eclipse of August 21, 2017 is coming up quickly! This is the first eclipse to be visible in the continental U.S. in almost 40 years. More details here: https://eclipse2017.nasa.gov/.
In such an eclipse, the Moon gets in front of the Sun and blocks some or all of its light. In Oakland, we will have a partial eclipse, with 76% of the Sun’s area covered by the Moon. For us, the eclipse will begin at 9:01 am, and reach maximum at 10:15 am. By 11:37 am, the Sun will be uncovered once more. Such a partial eclipse -- where some of the Sun’s bright surface is showing -- is not safe to look at with the naked eye (or sunglasses). You must use special eclipse-viewing glasses or project an image of the Sun!
Your Oakland Public Library is a distribution site for safe viewing glasses through a partnership with StarNet Libraries. We have a limited number to hand out to individuals and families, starting next week. If you need a large number for a group or class, please purchase them in bulk at this site, which offers discounts to educators. These glasses have a special filter material that reduce the light of the Sun so much that it’s safe to look at.
These glasses can be used to look at the Sun any time, not just during an eclipse. Also, note that it's not the eclipse that's dangerous to look at - it's the Sun. The Sun’s intense rays can cause serious damage to the sensitive tissues of the eyes, and we might not even notice any damage. Normally, our common sense protects us from looking directly at the Sun for more than a second. But during an eclipse, astronomical enthusiasm can overwhelm common sense, and people can wind up staring at the Sun for too long.
An illustrated booklet on how to prepare for explaining and viewing the eclipse can be downloaded free at http://www.starnetlibraries.org/EclipseGuide/. It has more information (and detailed instructions) on simple, safe-viewing techniques, such as using a colander to project many shadow images of the eclipsed Sun or a covered hand-mirror to reflect the eclipse image on to a wall.
We also have a program scheduled with Andrew Fraknoi, Chair of the Astronomy Department at Foothill College, about the eclipse and safe viewing practices, on Wednesday, 7/26 at 6:30 PM, at the Main Library. We're also hosting a live viewing party on the morning of 8/21. We'll have glasses to distribute at both events.
(A special thanks to Andrew Fraknoi for his help in creating this blog post.)