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International Space Station Viewing

06/07/2018 11:59 PM

For the last few nights, our local weatherman in Omaha Nebraska has told us the ISS was viewable shortly after his report ~10:30PM. He told us where in the sky to look - to the south. AND it was only in sight for about 3 minutes.

We have sat outside to watch a couple times now and just loved the event. My main thought - why is it only viewable for 3 minutes?

My only guess is the height of the station and how/when it reflects the sun's rays. Am I close?? Is this a recent thing to see the ISS or do timing/conditions have to be right?

Too bad this was right after my wife's uncle leaves the area and goes back to his teaching job with a telescope in Hawaii!!

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#1

Re: International Space Station Viewing

06/08/2018 12:35 AM
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#2

Re: International Space Station Viewing

06/08/2018 4:36 AM

There is an app available for most tablet devices that gives up-to-the-second detail on where the ISS is at any moment. The app also displays live video streaming from the station looking outwards when the cameras are able to transmit.

And as to viewing opportunities, one ought not to be surprised that opportunities are as short as 3 minutes: there's not many other vehicles doing ~17000mph relative to the ground at the moment!

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#3

Re: International Space Station Viewing

06/08/2018 7:54 AM

Why is the viewing time short?

...it orbits roughly every 90 minutes.

...it has to be high enough overhead from your particular location to see well.

...it cannot be day light when you can see it.

...the orbit is pretty close compared to the size of the Earth.

....so much of the time if it is not in daylight, it is in the shadow of Earth.

....this results in brief irregular periods for particular locations every few days a little after it gets dark or a little before it gets light.

Here is the app.

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#4

Re: International Space Station Viewing

06/08/2018 11:33 AM

The distance to the horizon can be calculated as:

(Fairly close approximation for the distance involved.)

where d is measured in miles and h is in feet. If h = 254 mi * 5280 ft/mi, the altitude of ISS, then it will be on the horizon in 1412 miles. So if it went directly overhead, the maximum possible distance and you could see from horizon to horizon, it would travel 2824 miles while in sight.

Traveling at 18000 mph, or 300 miles per minute, it would cover that distance in less than 10 minutes. Unless you are at sea, you cannot see all the way to the horizon and close to the horizon there is a lot of atmospheric absorption and many times clouds. So 3 minutes is not too unreasonable.

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#5

Re: International Space Station Viewing

06/08/2018 12:12 PM

You might want to take a look at this site https://www.heavens-above.com/. They have a lot of interesting information related to stars and satellites (ISS is basically a satellite). One of the most interesting areas of this site is the ability to list all the satellites that will go overhead on any given evening. Go to the "Daily Predictions for Brighter Satellites" page, update your location and get a viewing chart for any evening you want. It will include the time, satellite name, brightness and location of the start, peak and end of the viewing opportunity.

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#6

Re: International Space Station Viewing

06/08/2018 2:28 PM

Coolest ISS video EVAH!

Done by Destin of the YouTube channel 'Smarter Every Day', and his crew.

https://www.youtube.com/watch?v=lepQoU4oek4

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#7
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Re: International Space Station Viewing

06/08/2018 2:36 PM

Awesome!

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#8

Re: International Space Station Viewing

06/08/2018 4:46 PM

The ISS isn't the only satellite that can be seen in the night sky. I've been using N2YO for several years now. I was fortunate to be able to share the last Space Suttle flight (Atlantis) with 2 of my nieces, flying over while docked with ISS. That was AWESOME!!

N2yo tracks several satellites with prediction times that are accurate, pretty cool site

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#9

Re: International Space Station Viewing

06/08/2018 6:29 PM

Like all satellites in LEO, it is only visible during nautical twilight (Sun is less the 12 degrees below the horizon). Or shortly after sunrise/before sunset. The farther north you live, the more satellites you can see, most are in N/S orbits. The biggy is Iridium, if you catch one when the panels are in the correct position, it is extremely bright. It is called an Iridium flash. I think @Lynn worked on these

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#10
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Re: International Space Station Viewing

06/08/2018 8:31 PM

I didn't work on Iridium, it was commercial and I was military. I did know the gentlemen who conceived it. I had heard that the initial system concept was documented on a bar napkin. I left Motorola before it was fully operational.

The initial system was before its time, very expensive and never was commercially viable, until later.

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#11
In reply to #9

Re: International Space Station Viewing

06/08/2018 9:19 PM

I've seen some Iridium flares. The brightest ones are incredibly bright. Spooky in a way, to suddenly see a pinpoint of light up in space suddenly appear and shine brighter than Venus, glow super-bright for maybe 10, maybe 20 seconds, then almost as quickly fade away. Almost as if an alien spacecraft appeared, then disappeared.

I used to check the website Heavens-Above.com for info on Iridium flares, ISS transits, and so forth. But I haven't had the opportunity to do much of that lately. I suppose the website is still good.

Edit/update: Yes, the website is still good. There is a note there, though, about the Iridium flares. The original satellites used for the Iridium system are getting old and are being de-orbited. The newer satellites won't produce the dramatic flares of the old ones. (The flares were due to sunlight reflecting off the satellites' large mirror-like solar panels.)

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