I was going to put this in TWoP but theschnauzers found a more elegant way to pin down the date. Here’s to accuracy.
There is a way to use the Moon to determine whether the leg took place on July 26th or July 27th. I know, everyone is groaning, but if you follow along I think you may find this satisfying.
In the past we have use the phase of the Moon to set a date for a shot. Later on, we were (or more specifically I was ) tricked by canned shots of the Moon suck in willy-nilly. How many times have we seen that airport takeoff where the wing slowly passes through the full Moon? Lots.
This time I have a whole new approach using the
Moon’s position to distinguish between two dates.
This shot was taken as the Bransen’s balloon just lifts off the ground. If you look closely you will see that the Moon is also in the shot. It looks very small because the Moon subtends only one half of a degree of arc in the sky. Photographers often make the Moon look larger in photos by using a special lens. So we expect it to look larger. And there is the
“Moon Illusion” that psychologists have studied for years. Believe me,
that is the Moon in the shot. According to
this site, at 6:52 am*, on July 26th, 2005, in Park City, Utah the Moon’s altitude (the angle up from the horizon) was 51.9 °. It’s up pretty high. That’s how it manages to get into the shot. But it is not the altitude that helps us determine which day it is. The Moon’s azimuth will be the distinguishing feature of the day. In particular, what we can measure from the shot is the azimuthal angle
between the Sun and the Moon.
If you ever see the Moon at the same time on two successive days you may have noticed that it has changed its position. It lags behind by about 15° each day. That is plenty big enough to measure. So (using the same site), at 6:52 am on July 26th the difference between the Sun and Moon’s azimuth angles was: 201.9 - 68.6 = 133.3°. And on the 27th it was 183.8 - 68.8 = 115.0°. Now, look at the shot. Since it was taken from almost perfectly below the balloon we can measure the angle by using the balloon itself as a big protractor. Doing that we measure that the apparent angle from the Sun to the Moon is 128°. That matches best to the 133.3° predicted by the astronomical data for
July 26th.
*Here is where the 6:52 am time of shot comes from:
Driving from:
Park City High School
1750 Kearns Blvd, Park City, UT 84060
To launch site:
6250 Silver Creek Dr Park City, UT 84098
Google Maps has it at 5.3 miles and taking 8 min. Let’s make that 9 min due to towing a trailer full of balloon gear.
The Weavers would be getting there at 6:00 + 10 + 10 + 10 + 9 = 6:39 am. The Bransen balloon appears to be a hemisphere on the ground when the Godlewskis arrive. So that amount of progress is achieved in 10 min. By the time the Linzes are a few hundred feet up the Bransens look ready to go and the Weaver’s balloon is now one of those hemispheres on the ground. So that shot was at 6:39 + 10 min = 6:49 am. . So the Bransens probably got off the ground 3 min later at 6:52 am for the looking up shot.
Thanks Slowhatch!
