Nice video,
but are you sure you've seen Vanguard 1 and not e.g. its spend upper stage?
I am wondering because, why should a (almost) sherical shaped sat vary that much in luminosity...
/Kuddel
I'm very sure. For one thing, after all the decades that have passed since it was launched, its upper stage's orbit has drifted quite a bit from the actual satellite. In fact, as I check heavens-above right now, they're nowhere near each other:
http://heavens-above.com/orbit.aspx?satid=16&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET
http://heavens-above.com/orbit.aspx?satid=5&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET
The telescope is looking at Vanguard with a fairly high level of magnification compared to your eyes or binoculars as well, so it's very specific at what it's pointing at and tracking. This was tracked using Vanguard 1's orbital data and it was the only satellite there. It's a fair question though, intuitively it makes sense that the rocket booster could be a confounding factor, but in this case the booster is nowhere near the satellite nor do they share the same orbit (different right ascension of ascending node, etc).
Even had the booster passed through the field of view, which would be extraordinarily rare, it wouldn't have stayed there the whole time I tracked it, it would have passed through quickly since this is a very tight field of view.
As to why it changes in brightness like that, it is roughly spherical, but it is spinning (now much slower than at launch thanks to magnetic torque), and it is not even in albedo throughout. Its solar cells are actually quite dark and it also has a tube-like separation mechanism that may not reflect light that well when its pointed at you depending on the angle to the sun. Basically I think the solar cells have the most to do with it though. Notice the bright reflection of the sun in this image of Vanguard 1:
http://www.calchautauqua.net/ChautImages2010/Green Energy/Vanguard 1.jpg
Now imagine the angle were such that that dark solar cell were at the spot where the sun is reflecting... you wouldn't see the satellite nearly as brightly (and even when you do spot it, it's very dim).
) I want to strongly emphasize that if these images are posted somewhere else without my permission you are violating Copyright law and I WILL TAKE ACTION ACCORDINGLY !! as this person whom did so found out.
)
