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Photo of satellite?

  1. Sep 10, 2006 #1

    DaveC426913

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    I'm highly skeptical. This guy claims to have just luckily caught this pic of a satellite through his scope with a handheld digital camera.

    Is this plausible at all?

    http://img237.imageshack.us/img237/4535/dscn0210mq7.jpg
     
  2. jcsd
  3. Sep 10, 2006 #2

    Kurdt

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    Interesting shot whatever it is.
     
  4. Sep 10, 2006 #3
    i don't see anything that looks like solar panels, the ovals are odd. I suppose they would be tilted dishes but... we'll never know. Unless does it have a time associated with it? cause then we could see if there was a satellite in the area.
     
  5. Sep 10, 2006 #4

    russ_watters

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    It's about the right size. Heckuva lucky shot, but I'd say it is probably legit. If you can find where/when it was taken, I may be able to verify it with StarryNight....
     
    Last edited: Sep 10, 2006
  6. Sep 10, 2006 #5
    Where did you find this? Send me a message.
     
  7. Sep 10, 2006 #6
    I did some rough calculations using the following very rough approximations:
    Moon ~ 1482 pixels vertical
    Object ~ 24 pixels vertical
    Moon Diameter ~ 3476km
    Average Distance to Moon ~ 385000km
    Average Distance to a Orbiting Satellite (This is where it gets tricky, it can range anywhere from about 480km [low-earth orbit] to about 35,760km [geostationary orbit]. For this, lets assume it is in low-earth orbit (best chance of actually seeing the satellite)) ~ 480km

    With some quick algebra we find that the actual satellite would appear to be 70m in length...feasable considering these are very rough calculations, and if you can refine them, that could make it more convincing.

    Math:
    (24px/1482px)*3476km = 56.29km <- Projection of satellite onto surface of moon
    (480km)*(56.29km/385000km) = 0.070km = 70m <- Projection of satellite demensions onto a plane 480km into space

    As for the image itself, it seems as if there is a lighter edge around the edges of the 'black blob'. This may be from the moon itself, seeing as how the bright light from the sun would tend to 'invade' the edges of the darker object, a common phenomenon in photography and eyesight in general. Any ideas?

    In conclusion, I do believe that this could be a real lucky image of a satellite overhead, however, it seems that it could also be an easily doctored image.

    *EIDT* P.S. - I believe this is only my second post on the forum. I hope to post much more in the future.
     
  8. Sep 11, 2006 #7
    looks like four balloons to me. No way it would be a satellite, would be way too big, and it doesn't appear to be streaking across the image.
     
  9. Sep 11, 2006 #8
  10. Sep 11, 2006 #9

    Kurdt

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    Well from downloading the photo and looking at the summary it was taken on 9/9/06 at 12:56. Now we just need the position.
     
  11. Sep 11, 2006 #10

    russ_watters

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    Thanks. I was too lazy for that. But...
    LEO is 100-300 miles (160 - 380 km). The ISS flies at 220mi (360 km). The Hubble is at the extreme limit of the Shuttle's range at 353 miles (569 km).

    So the altitude could be as little as half to a third what you used and thus the size could be half to a third (20 to 35m) what you calculated. That would be more reasonable, but it is still pretty big to be a satellite.
    A reasonable possibility, though with the short exposure for a moon pic, I doubt there'd be any motion blur.
     
  12. Sep 11, 2006 #11

    Kurdt

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    The exposure time was 1/229 seconds according to the data on the image so with a few crude assumptions a satellite could travel approx. 30 meters in that time. if I'm not too shabby with my rough estimates taht would translate to a 1 second of arc movement. This is about 1/1800 the size of the moon so my guess is blurring would not really be discernable.
     
  13. Sep 11, 2006 #12
    I saw that pic too Dav, and I am also sceptical...

    He says it was done with a 'cheap digi-cam' (his words) held up to the eyepiece of a 8" newt.

    First of all - the resolution of that pic is something around 2250 x 1700 (about 4 megapixels) - so - OK - maybe just about borderline 'cheap digicam'
    However, the Moon just about fills the frame, and I don't see any vignetting around it - so if it was truly taken through an eyepiece, then I'm guessing it would have had to be cropped, and the original image may have been quite a bit higher resolution.

    Another thing is that it is an incredibly good image of the Moon, to have been done by that method. I've tried similar myself, with GOOD digital cameras, and never got anything near as clear and well defined as that shot - only way I've ever had images that good was by using the 'prime focus' method.

    Kurdt....
    If, as you say, the satellite would travel 30 metres (approx) in that time, then surely there WOULD be motion blurring.
    30 metres will be a sizeable percentage, af even the largest satellites, so surely the image would be 'smeared'?

    Just one more thing to consider - look around the edges of the Moon - there is a slight blue-ish edge... Chromatic aberration? - From a reflector?
    OK - it is only slight, but it IS there - I suppose it could be from the eyepiece - but could it maybe also be consistent with either a good quality achro (or semi-apo) refractor? - or maybe some sort of Cassegrain model, with a focal reducer lens added to lower the magnification?

    Overall - inconclusive.
    It may be faked, or could be an INCREDIBLY lucky shot - hard to say for sure.
    Or maybe it IS genuine, but not his pic??????
     
    Last edited: Sep 11, 2006
  14. Sep 11, 2006 #13

    DaveC426913

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    "The photo was taken at 12:56AM EST, at 40N 73W."
     
  15. Sep 11, 2006 #14

    Kurdt

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    Yeah I think I bodged that calculation thats why I posted the warning with it. 15 arcseconds is more likely and is very much more visible.

    Here is the camera he used

    http://www.nikonusa.com/template.php?cat=1&grp=2&productNr=25546

    shutter speed was 1/229 seconds and iso was 50.

    As people who photograph the moon should know this is a fairly slow exposure I normally photograph at iso 1600 for 1/2000 of a second.

    i'm fairly skeptical about this photograph now. could just be a bit of debris that has fallen onto the mirror or eyepiece or camera lens. The shape would also indicate that to me as it does not look too much like a satellite.
     
  16. Sep 11, 2006 #15

    Kurdt

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    Oh cool I'll check starry night.
     
  17. Sep 11, 2006 #16

    Kurdt

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    Mine doesn't have a full list of satellites unfortunately but I'm sure someone will.
     
  18. Sep 11, 2006 #17
    I have SN5 pro - I'll give it a shot - I'll also update sat info before checking...

    How far off GMT is EST? - and what date was the pic taken?

    edit - I just saw the date - D'oh!
     
    Last edited: Sep 11, 2006
  19. Sep 11, 2006 #18
    Forget that last question - I just entered New York as location.

    Ran it through, and there was nothing (listed in SN-5 pro) within 15 mins either side of 12.56am, that got aywhere near the Moon.

    Looking more like either a fake, debris on EP/cam/scope, or something terrestrial, like the aforementioned 'balloons'

    I still think the pic is possily TOO good to have been done handheld with that camera though.
     
  20. Sep 11, 2006 #19

    tony873004

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    I think its balloons. If you consider a balloon to be a foot long, or about 0.3m, then you count pixels of the object and compare it to the Moon's pixel count, The balloons would be about 2.5 km from the observer.

    I've been searching the web trying to figure out how high a normal helium-filled party balloon would rise. Most sites say they will pop from the decreased pressure, but I'm not sure. There's pleanty of stories of balloons with attached notes travelling hundreds of miles. If they were going to pop, I imagine they would reach pop altitude way before they had a chance to travel more than just a few miles.

    So my guess would be that as the balloon rises, and the air pressure outside the balloon decreases, that the balloon's buoyancey would decrease until the balloon reached a cruising altitude. And I'm guessing cruising altitude would be below pop altitude.

    How high that would be depends on a lot of factors, but I imagine it would be in the low thousands of meters, consistent with my estimate of 2500 meters.

    The author of that picture claims it took the object about 4 seconds to cross the Moon's disk. This is too slow for orbital velocity of a LEO satellite. If I'm right about it being 2.5km altitude, that would be about 10m/s, about what I'd expect for a moving mass of air at that altitude.

    Any thoughts?
     
  21. Sep 11, 2006 #20

    russ_watters

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    If the time is off by an hour, there are several that pass close, but nothing at all nearby at the indicated time.

    One thing about that angular velocity - that's the angular velocity at zenith. It is much slower near the horizon because it isn't moving perpendicular to your sight line.

    I think it still could be a satellite, but the time, date, and/or location would have to be off by a little.
     
    Last edited: Sep 11, 2006
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