It is not too early to begin preparing for the Great American Solar Eclipse of Aug. 21, 2017 — and the sun's position on April 19, 20 and 21, but especially April 20, will offer a perfect dress rehearsal for that historic event, NBC News reported.
During these three days, the sun will track across the sky along a path that will be very similar to the path it will take on the actual eclipse day, Aug. 21.
In fact, the path that the sun will take on Friday, April 21 will virtually match its track on the day of the eclipse.
U.S. & World
The only other significant difference is that the sun will arrive at its eclipse-day position about 4 minutes earlier on the three April dates compared to Aug. 21.