Every week we get a huge military plane flying right over our garden. I am no expert on planes but it looks very much like the Boeing C-17 Globemaster.I know when it’s coming because it is ten times louder than the holiday planes that are on there way to Exeter airport.
It never lands, just goes around twice then heads back to wherever it came from. (my guess is Cyprus). Apparently they are notoriously difficult to handle when landing and taking off and a few of them have crashed.
I could pretend I know what I am on about and say “The wobble of the Earth” but I am really not sure, I would need to check that one, I know it does take a slightly different path each time and it will depend on where the Sun is I suppose…
Hoping this helps,re the time differentials…the ISS is NOT in an equatorial orbit. An equatorial observer of a vehicle with a 92.75 minute prograde equatorial orbit would see successive passes separated by circa 99 minutes. All passes would be almost identical,with the vehicle moving from west to east and passing straight overhead. Where you are,you’re seeing it from a more northerly aspect,thus it seems to be moving at different speeds [times of visibility] on different passes. You have to account for the variance in the Earth’s ‘polar orbit’,as well as it’s ‘Sol orbit’.
The ISS is instead in an orbit inclined by about 51.6°. This changes the geometry considerably. An observer might see the first of two consecutive passes starting in the south and disappearing in the southeast, while the second pass might start in the southwest and disappear due east. The zenith passage of the two events corresponds to a 360°+15.5°change in true anomaly rather than the 360°+25° change for the equatorial orbiter.
So although the ISS orbit is centred on the Earth, it doesn’t follow the same orbit as the Earth. A bit like drawing a straight line on a spinning ball I suppose.
