# QuestionDistance of space stations .

#### dancingstar

As far as space stations are concerned, given that it is in a certain fixed orbit in the Earths gravitational field , it is quite easy then to calculate its distance, but could you please give me a rough estimate of their distance from Earth.

#### Helio

I think that the ISS orbit is 220 miles. So it must be overhead to be that close to an observer. When it comes over the horizon it is about 900 miles or so from the observer.

dancingstar

#### dancingstar

Is there a radiation belt on other planets? like the Van Allen Belt?

#### Helio

Is there a radiation belt on other planets? like the Van Allen Belt?
Yes, I think any planet with a magnetic field will have those belts.

Venus and Mars do not have much in the way of magnetic fields. Jupiter has belts 200k times stronger than ours. Jupiter's is so powerful that space probes require much greater protection, which makes trips to Europa especially more costly.

#### dancingstar

Interesting link, Thank you . What fascinates me as well is the visibility of the satellites moving across the night sky at speed, and are visible to the naked eye , they must be a tremendous distance away. How high are they and do they come close to each other?

#### matthewota

We saw it last night after using the tracking info. It is very bright when it passes soon after it gets dark or during the pre-dawn hour. We saw a 7 pm pass in clear skies. It was a 6 min. pass. It was the brightest object in the sky.
That is because it is night time at your location and the ISS is still in sunlight as it passes overhead. Once it gets into the Earth's shadow it vanishes.

#### Helio

That is because it is night time at your location and the ISS is still in sunlight as it passes overhead. Once it gets into the Earth's shadow it vanishes.
Yes, that is important to remember for the late night observers.

Those on the ISS are on Universal time, so they are 5 hours ahead of us on CDT, so they are usually asleep, I think, when they fly over the Americas.

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