Debunking "That's not a Space Station, it's an airplane"

Sam Hill

New Member
I took a look at some projected ISS transits over the United States, looking for one for which I could pick two observers with simultaneous and directly opposite observing locations. I found one on March 6, 2016 that fit the bill: it had a maximum apparent elevation at 5:00:40am Spokane WA time, and 5:59:39am El Paso TX time, one time zone over. Maximum elevation only 61 seconds apart, that's the best I could do for a simultaneous observation, and those observers in those two locations were looking pretty much directly at each other. This is important, because it means the angles of elevation from each location can be used to calculate the elevation above ground of the object being observed. Spokane and El Paso are 1237 miles apart, according to Google Maps "Distance Measure" tool. (I understand that an FE supporter might challenge that distance as being tainted by RE math, and I'll come back to that.) According to the ISS Astroviewer page (links at the bottom) an observer in Spokane saw the ISS rise to a maximum elevation of 14° above the horizon to the South East, while the El Paso observer saw it at 21° to the North West. Taking for the moment a flat-earth model, we thus have an obtuse triangle with a side (ground distance between the cities) and two angles known, we can calculate the rest. The angle formed at the vertex occupied by the object in the sky is 145°. The Law Of Sines allows us to calculate the line-of-sight distances from each observer to the object. The Spokane leg of the triangle is 772.9 miles, and the El Paso leg is 521.7 miles. From there, we can calculate the height above ground of the object using the Law Of Sine again, calculated using each observer's angle. The result is 186.97 miles high. This is far, far higher than any known aircraft has ever flown, or ever could fly. Therefore, we can conclude that the object observed at the sky location projected to contain the ISS is not an airplane.

Possible objections:
1) Maybe the elevations are wrong? I think we can take the projected elevation angles as accurate (instead of going out and observing it ourselves) because if they were not it would be very easy to expose the error, and should have been done by now. Amateur astronomers use these online resources without reporting massive errors, after all.
2) Maybe the distance from Spokane to El Paso is wrong? Perhaps it is, I'll grant you that. Let's say we call it 1 'ground unit' of unknown distance and do the math that way. We end up with the object being at an elevation of 0.15 ground units. Or put another way, Spokane and El Paso are 6.5 times as far apart as the object's elevation. Commercial aircraft typically operate with a ceiling of 42,000 feet, or 8 miles, so if the object is a commercial aircraft then El Paso is only 52 miles from Spokane. The aircraft with the highest known operating ceiling ever, the SR-71, could fly as high as 85,000 feet, or 16 miles, so if the object is a spy plane then El Paso is only 104 miles from Spokane. I think we can all agree that El Paso and Spokane are much farther apart than this.
3) A one minute time difference between observations? Maybe that is too much difference for these observations to be comparable when the object is visible for only four minutes? Seems like it is, yes. However, the object sweeps across the sky in a fairly flat curve, especially as viewed from Spokane. It rises from 10° to 14° and falls back to 10° during the transit. Doing the math again with Spokane's lowest elevation still yields an elevation of 149.46 miles, far too high to be any airplane we know about.

Spokane: http://iss.astroviewer.net/observation.php?lon=-117.4260466&lat=47.6587802&name=Spokane
El Paso: http://iss.astroviewer.net/observation.php?lon=-106.4850217&lat=31.7618778&name=El Paso
 
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