All the preparations, all the excitement and all the planning that is going into this Great American Eclipse event on August 21, 2017 will certainly pay off with an amazing experience. But if you want to see if your special spot or secret location in Perry County is in fact perfect then you want to be there on practice day, April 20, 2017.
When astronomers give the Sun’s position, they use the two celestial coordinates, right ascension and declination. These two values roughly correspond to latitude and longitude on Earth. On August 21st, the Sun’s declination will be approximately, 11 degrees 51’. So, if you want to “practice” observing the Sun where it will be on eclipse day head to your “spot” on April 20th. The Sun’s path through the sky will be the same as it will be on eclipse day.
You will want to be there during the same time as Perry County’s “totality” which will occur at 1:18pm. Maybe you want to set up a filtered telescope, run a test launch or take a few pictures. Maybe you just want to check out a perspective observing site. How far away are any trees? Are you too close to any buildings? Can you see the horizon? The Sun will be high in the sky when the eclipse passes over Perry County so obstacles blocking your view are less likely than someone in Oregon or South Carolina witnessing the eclipse’s sunrise or sunset. That too makes our area highly desirable, no eclipse pun intended. To have trees and obstacles around you will be good as certain phases of the eclipse will show eerie shadows, crisp sharp lines and the leaves on a tree can provide a kaleidoscope of mini eclipses fun to look at just as long as these obstacles do not block your viewing of the Sun and the experience of seeing the Corona.
Anything you want to try on eclipse day you can practice April 20th because it is the closest approximation to what you’ll see on eclipse day. The Sun will rise and set around the same times, and it will cross the meridian (the imaginary north-south line that passes through the overhead point; the Sun crosses it at midday) the same time as on eclipse day.
Here’s something to consider, however. The Sun’s declination doesn’t change all that much from day to day. In fact, if your rehearsal occurs as many as 3 days before or after April 20thyou really won’t notice a difference when August 21, 2017 gets here.
My advice, don’t get all caught up in the scientific mumbo jumbo. Just know to scout your location so you have a plan on eclipse day. Whether you’re planning a backyard eclipse party, family viewing destination or public viewing site get you a pair of eclipse glasses go out and look at the sun and prepare to be amazed August 21, 2017.