Skywatch Line for Wednesday, June 9, and Thursday, June 10, 2021

This is Dudley Observatory’s Skywatch Line for Wednesday, June 9, and Thursday, June 10, written by Alan French.

With clear skies and a good view to the northeast, we’ll have a view of an in-progress partial solar eclipse as the Sun rises Thursday morning, June 10.

A proper, safe filter is an absolute necessity for viewing the partially eclipsed Sun. Direct sunlight or an inadequate filter can permanently damage the eye. In the past, people have tried viewing the Sun through smoked glass, exposed photographic film, stacked sunglasses, crossed polarizing filters, neutral density filters, CDs, and metalized candy wrappers. These are not safe and should never be used. While they seem to dim the Sun, they let infrared wavelengths through that can permanently damage your retina and cause lifelong vision loss. Only use a filter designed specifically for solar viewing, like solar eclipse glasses, or a shade 14 welder’s plate.

Many of you probably have eclipse glasses or shade 14 welder’s filter plates from the August 21, 2017, solar eclipse. If not, you may be able to find a shade 14 welder’s plate at a local welding supply store. Such a dense filter is not widely stocked, so call around. The 2-inch by 4-1/4-inch filter plates, generally costing $2 to $3, are perfect for viewing through both eyes. Larger versions, designed for helmets, may also be available.

If a shade 14 is not available, the filters are additive, so a shade 5 and a shade 9, held and stacked together, with both eyes looking through both filters, would be equivalent to a shade 14.

If you have eclipse glasses, hold them up to a bright light and make sure they have not developed pinholes or become scratched. If they are damaged, don’t use them.

If you do not have a suitable filter, make a pinhole projector, a safe way to project an image of the partially eclipsed Sun. For details visit How to View a Solar Eclipse | Exploratorium.

If in doubt, real time eclipse coverage is available online. Search for coverage or visit How to watch the ‘ring of fire’ solar eclipse online on June 10 | Space for sites streaming the eclipse as it occurs. It’s also a good backup if the weather does not cooperate. Most coverage starts at 5:00 a.m. EDT on June 10.

From Schenectady the Sun rises at 5:18 a.m. EDT Thursday, 12-degrees east of northeast (azimuth 57-degrees). The eclipse will reach its maximum at 5:35:36 when 75-1/2 percent of the Sun will be covered by the Moon. At that time the Sun will be just over two degrees above the horizon. The eclipse will end at 6:34:26 a.m., when the Sun will be 12 degrees above the east northeastern horizon.

For more on safe eclipse viewing visit How to View a Solar Eclipse Safely | Solar Eclipse Across America (aas.org).

More details and a link to get precise predictions for your location can be found at A Sunrise Annular Solar Eclipse – Sky & Telescope – Sky & Telescope (skyandtelescope.org).

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