Jupiter 20th July

[Neil M]

I was observing Jupiter for only the second time during Sunday night / Monday morning and at approximately 12.50am I saw a very small black dot travelling across the planet's disc. It took only about a second or so and obviously took me by surprise. If memory serves it was travelling from the lower left to upper right as viewed in the eyepiece of my refractor.

I'm pretty sure, even as a complete novice, that this was nothing to do with the optics of my scope in any way, and assumed that as the 'dot' was in focus that it was a shadow being cast onto the planet.

Having now read about the recent impact on Jupiter I'm tentatively wondering if I saw something relating to this.

[Talitha]

Hi Neil, i'm not sure how close to Jupiter an object would need to be in order to stay in focus while you're observing.. anyone have an idea?

My first instinct was to say that you may have seen a bird, because this has happened to me while lunar observing. Although the silhouette wasn't in focus, the shape was easily recognizable. But the Moon's a lot larger in the sky than Jupiter, so it's possible that if it was a bird it would have been seen as a very fast moving dot.

Or maybe (lucky you) it was the ISS/Shuttle? Again, i have no idea if they would even be visible when silhouetted against Jupiter, but imagers have captured the ISS flying in front of the Moon so i guess it's do-able.

Does anyone know if a 'live' astro program would show if the docked crafts would have passed near Jupiter? Wow, that's a feather i wouldn't mind having in my cap.

[Neil M]

Hi Talitha - I've just had a quick look at Heavens Above and, if I'm using it correctly, timings don't match. I hadn't thought about the possibility that it may have been a bird, although it appeared to me to be circular albeit very small and with very uniform movement.

[arad85]

Having now read about the recent impact on Jupiter I'm tentatively wondering if I saw something relating to this.

Unlikely as the impact happened before Sunday afternoon UK time. For it to be moving so quickly, it would have to be much closer to home. Given Jupiter is 133000km pole to pole, for something to be close to Jupiter and move across it in 1 second means it must have been travelling around half th speed of light!!!

More likely a bird, plane or perhaps even a blood cell in your eye....

[Jake Bullit]

Could it have been this?

Impact mark on Jupiter, 19th July 2009

[Neil M]

Jake - I thought there may be a very small possibility that it was related, not the impact object itself but a secondary object. Would have been pretty cool to have seen that.

arad85 - the speed of movement was bothering me too, although it may have been two seconds it would still have been moving pretty quickly! My gut feeling is that it wasn't a bird or a plane, although I'll keep an eye on the local flight paths into and out of BHX.

[crovax]

My vote for sattelite (shuttle, ISS, etc). While observing sky I quite frequently saw sattelites and once I managed to follow Progress-M (that for some reason was as bright as ISS) for about 5 secs. Well, when I saw those objects they were bright and nothing like a black dot but IMHO if they are in the position where light is not reflected from them and the appearant magnitude is low, they can be seen as black dot (of course having a bright backgroud like Jupiter). Also CNN says that the objects was around 50-100 miles across and I doubt that it can be that easily visible from that distance.

PS. I am still a big noob so don't take the above post too seriously ))

[Neil M]

I think I'm with you crovax - a satellite seems the most likely explanation.