This Veterans Day memorial is ‘perfect’ only one day a year

Credit: Mike Spinelli via onlineatanthem.com

ANTHEM, Ariz. — It’s a “perfect” tribute that can only be seen on Veterans Day each year.

The Anthem Veterans Memorial, located in Anthem, Arizona, is a monument dedicated to honor the service and sacrifice of our armed forces.

According to the city’s official website:

“At precisely 11:11 a.m. [PT] each Veterans Day (Nov. 11), the sun’s rays pass through the ellipses of the five Armed Services pillars to form a perfect solar spotlight over a mosaic of The Great Seal of the United States.”

The city writes:

“This pillar of pride provides a place of honor and reflection for veterans, their family and friends, and those who desire to show their respects to those service men and women who have and continue to courageously serve our county. The five pillars represent the unity of the five branches of the United States military serving steadfast together. They are staggered in size with their appropriate military seal placements on each pillar based upon the Department of Defense prescribed precedence.”

Jim Martin, AVM chief engineer, explained the engineering behind the memorial:

“When planning the geometry of the Anthem Veterans Memorial, it was clear that the static nature of the structure would require a fixed azimuth (the horizontal angle from astronomical north to the center of the sun on Nov. 11 at 11:11 a.m. that creates the horizontal illumination of the Great Seal) and a fixed altitude angle (the vertical angle for zenith, or horizon, to the center of the sun on Nov. 11 at 11:11 a.m. that creates the vertical illumination of the Great Seal).

Each year, the center of the sun is slightly offset from other years by just a few horizontal or vertical arc-seconds relative to the timing of the required azimuth/altitude position of the sun. This does create a time correction that is very minor; it cannot be perfectly aligned at precisely aligned at 11:11:11 a.m. every year due to the static alignment of the memorial. To deal with this adjustment, we calculated the perfect solar position every year from 2011 to 2111 and at what time (International Atomic Time plus corrections) perfect illumination would occur. The time variance over 100 years was calculated to be a cyclical range of perfect illumination sometime between 11:10:58 AM and 11:11:22 AM, a difference of 24 time seconds.

Using the statistical mean of the 100-year data, the altitude and azimuth angles for the structure were adjusted to provide time/error fluctuation of plus or minus 12 time seconds from the International Atomic Time mark of 11:11:11 a.m. That small time difference allows for additional compensation of the variations that you mention. We also checked the variance 500 years out, and if the structure is still standing, it will work.

In complete truth, it is not perfect; the only way to do that would be to move the ellipses very slightly each year which is really not a recommended option. I would say that it is perfect if you recognize the plus or minus 12 time second difference for 11:11:11 a.m.”