THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.e70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Founded January 1970
Julian date: 2457966.16
"After all this time trying to sort out the components of Heaven, how curious to discover it consists of just an outdoor table and a cup of gelato."
THE DAILY ASTRONOMER
Tuesday, August 1, 2017
More Eclipse Questions
We're going to end the DA school year in a rather monomaniacal manner: focusing on the Great American Eclipse that, if all goes well, will occur on August 21, 2017. And, as you can probably guess, when it comes to celestial phenomena, there are precious few deviations from the itinerary.
Today's DA consists of some more solar eclipse questions. If you have your own, please share them!
CAN I SAFELY VIEW THE EVENT LOOKING THROUGH A WELDING MASK?
Not all welding masks are created equal. In order to safely view the Sun without causing eye damage, one would need to use welder's glass with a 14 rating! If you are using welder's glass, be sure you know the rating value. If that value is less than 14, PLEASE DO NOT USE IT. Also, one cannot combine welder's glass arithmetically. For instance, do not use two 7 rating welder's glass or one 10 and the other 4. Your eyes are precious! One can still inflict damage on them even if one is observing the Sun without pain.
YOU SAID SUCCESSIVE SOLAR ECLIPSES WITHIN A SAROS CYCLE ARE SEPARATED BY 18 YEARS, 11 DAYS AND 8 HOURS. DOES THIS MEAN THAT WE'LL SEE ANOTHER ECLIPSE IN AMERICAN IN 18 YEARS, 11 DAYS OR SO?
No. Because each Saros cycle eclipse is separated by 18 years, 11 days and 8 hours, each successive totality path will be displaced by the preceding eclipse of the same saros by about 1/3 of the distance around Earth. Let's examine the maps of four successive total solar eclipses from Saros Cycle 145:
August 11, 1999
August 21, 2017
August 11, 1999
August 21, 2017
September 2, 2035
September 12, 2053
August 11, 1999
August 21, 2017
September 2, 2035
September 12, 2053
One notices that each successive totality path is displaced by the previous path significantly. However, note that the location of the August 11, 1999 eclipse is somewhat similar to the September 12, 2053 eclipse. Three Saros Cycles, equal to 54 years and 33 days, is known as an Exeligmos. Successive eclipses in an Exeligmos cycle will have similar locations and properties. However, successive eclipses within a Saros will not be in the same location.
CAN WE WATCH A LIVE STREAM OF THE TOTAL SOLAR ECLIPSE?
Absolutely. Try this web-site:
WHEN WILL THE USA NEXT EXPERIENCE A TOTAL SOLAR ECLIPSE?
April 8, 2024. The totality path will slice across the USA but, unlike the August 21, 2017 event, it will not only cut across our country. [Note: the totality path will pass through western Maine.]
WHEN IS THE NEXT TOTAL SOLAR ECLIPSE ANYWHERE?
The next total solar eclipse occurs on July 2, 2019. The totality path extends from the south Pacific to Chile and Argentina
The totality path of the following total solar eclipse (December 14, 2020) will also cross into Chile and Argentina,