There was a near perfect ISS flyby over Sydney today after sunset. A mag-3.5 overhead at 87 degree according to heavens-above. As always I really enjoyed watching it but I swear I could, at the same time, hear a constant kind of humming sound of low frequency, kind like that of a propeller but a lot smoother. My question is: is it possible to HEAR a ISS flyby? I have watched numerous ISS flyby before and they were all silent.
1. ISS is in constant Free-fall and makes no sound.
2. Sound can't travel in Space and the ISS at approx 350k's high is far enough into space to not have any atmosphere for sound to travel in.
3. at Approx 350 k's away you wouldn't hear it even if it did make any sound.
You can occasionally hear meteors crackle as they go through our atmosphere though
Yes,Vincent-it was certainly a great pass over to see!!!
'Sam' in Canberra saw it at 5.54 pm.I first noticed it here (just north of Brisbane),at 5.56 pm and watched it till I could see it no more,in the N.E,at 6.01 pm.
Not sure what the most time one cane see it in the sky,but that would have to be close to some sort of record???. from my basic looking at time on mobile phone-at least 4 to 4 and half minutes.It 'curved' quite a bit too.
Actually come to think of I was disappointed my son packed up his cam corder on tripod,as he had it set up to capture '5.30 pm plane' passing close to the moon.Not sure what footage he would have been able to gather,but worth ago.
Cheers Chris.
(PS,to my knowledge I do not think it would be possible to 'hear it',I think its about 500 to 600 Km's 'up there'
Did anyone in Melbourne see it go over last night, approx. 7pm?
We were outside setting up the scope, and over it came from the West, and heading across to the East. Fully lit up the whole way, I'm not a mag. expert but surely brighter than Jupiter. I even had a couple of goes at trying to aim the scope at it.....no luck though!!
We had no idea it was going to come over, and I'm going to find out how often it crosses over here, to be at the ready next time.
Is the brightness dependent on the time it crosses? As it was just dark, it was very bright compared to all the other stars - and I'd guess the ideal time to view it - ; if it was flying over at say, midnight would it still be as bright?
BTW, it was silent, save a few gasps of wonder from us...
Did anyone in Melbourne see it go over last night, approx. 7pm?
We were outside setting up the scope, and over it came from the West, and heading across to the East. Fully lit up the whole way, I'm not a mag. expert but surely brighter than Jupiter. I even had a couple of goes at trying to aim the scope at it.....no luck though!!
We had no idea it was going to come over, and I'm going to find out how often it crosses over here, to be at the ready next time.
Is the brightness dependent on the time it crosses? As it was just dark, it was very bright compared to all the other stars - and I'd guess the ideal time to view it - ; if it was flying over at say, midnight would it still be as bright?
BTW, it was silent, save a few gasps of wonder from us...
So there's quite a few satellites that can be tracked........there's a lot of info on the site given (and comets too...) we've had a few looks at the Iridium flyovers in the past, and have noticed quite a few others pass through the scopes' viewfinder: considering the narrow FOV, there's a lot of them flying around up there.....someone had once said they get a bit annoying (maybe they spoil images??), but I don't tire of them.
Sydney can see another good flyby tonight at 6pm at mag-3.5
John, you will not see any satellite including the ISS at midnight simply because too far away from the sun to reflect any light. They only reflect sunlight at dawn or dusk.
Sydney can see another good flyby tonight at 6pm at mag-3.5
John, you will not see any satellite including the ISS at midnight simply because too far away from the sun to reflect any light. They only reflect sunlight at dawn or dusk.
I don't believe this is correct, you can see Satellites during all periods of the night, not only dusk, not to mention iridium flares all times of the night...
I don't believe this is correct, you can see Satellites during all periods of the night, not only dusk, not to mention iridium flares all times of the night...
You are technicaly right in seeing Satellites at all times of the night,but wrong to say you can see Iridium satellites at any time of the night as they are too close to the earths surface and so if the Sun is on the other side of the Earth cannot reflect the suns light as it is blocked by the Earth.
You need a telescope to see the very high Satellites after about 22.00hrs .
These Satellites are from about 10.000kms hight upto 30.000 kms which are usually the Geosynchro Satellites or Spy satellites.
Cheers
I believe you can see sat's throughout the night. Maybe at all altitudes.
Although I haven't looked for years, I can recall visiting Rob McNaught late one night in the 80's at the now defunct and mothballed UK satellite research unit on Siding Spring as he imaged sats near the south celestrial pole.
Heavens Above site will plot for most satellites, rockets and upperstages etc. I particularly like the 'variable' sats.
You are technicaly right in seeing Satellites at all times of the night,but wrong to say you can see Iridium satellites at any time of the night as they are too close to the earths surface and so if the Sun is on the other side of the Earth cannot reflect the suns light as it is blocked by the Earth.
You need a telescope to see the very high Satellites after about 22.00hrs .
These Satellites are from about 10.000kms hight upto 30.000 kms which are usually the Geosynchro Satellites or Spy satellites.
Cheers
Gyosynchro Sats wouldn't be hugely interesting to see would they? considering they'd seem much like a star, except staying at the same point in space throughout the entire night.
Gyosynchro Sats wouldn't be hugely interesting to see would they? considering they'd seem much like a star, except staying at the same point in space throughout the entire night.
Not screamingly interesting to look at.
They do, however, make an interesting image. I have used a 50mm lens pointed up at the celestrial equator and opened for about 15 minutes. The stars all trailed across the image but the geostat's sat to produce a point image. There were 4 or 5 almost equally spaced across the image in a line. If I can find and scan the image I'll post it. It was a long time ago.
They do, however, make an interesting image. I have used a 50mm lens pointed up at the celestrial equator and opened for about 15 minutes. The stars all trailed across the image but the geostat's sat to produce a point image. There were 4 or 5 almost equally spaced across the image in a line. If I can find and scan the image I'll post it. It was a long time ago.
I agree, and would love to see your image! I've photographed several but unfortunately never more than two in the same frame. Attached are the same satellite processed different ways from a number of fairly short subs, first stacked on the satellite and second stacked on the stars. Notice the relative brightness differences - in the first the satellite is reinforced, while in the second its brightness is 'diluted' in the stacking process.
There are literally Thousands of the suckers
