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Mary M.
Fort Lauderdale, FL
United States

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Have you seen the ISS?

Did you know that the international space station is visible at night from various points on earth?

You can check out where it is at any time of day by going to this link

http://iss.astroviewer.net

Have you personally seen it? It looks like a bright white light travelling across the sky, it is really neat to think that there are humans up there orbiting the earth and looking down on us.

What are your thoughts on the space station?

Can anyone explain in layman's terms how it stays in a particular orbit?

This is also a video on TED you might enjoy:

video-cady-coleman-talks-to-ted2011-from-the-international-space-station

Related Talks:

Lucianne Walkowicz: Look up for a change

Topics: NASA Wonder astronomy how universe works

Closing Statement from Mary M.

Krisztian and Ed........thank you so much for his interchange of ideas and information.

Keep looking up!!!

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Gail . 50+
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Feb 23 2013: Shoot a bullet out of a gun. It will go straight then fall. Do the same from the top of the leaning tower of Pizza (when no one is around). It will go farther because the distance to the ground (it falls at an angle) is greater. Do the same on top of Mt Everest, and it will go much further before it falls because it has so far to fall. Now go to a point in space and shoot that gun again. The bullet will continue to fall to earth, but because the earth is a sphere, it falls along the same lines as the earth's curved surface.
- Mary M. 100+
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  Feb 23 2013: Very simple explanation. Great for kids.
  
  Thank you so much.
  
  Have you seen the ISS?
Krisztián Pintér 200+
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TED Translator

Feb 22 2013: ah, about the question: it falls, but always misses the earth :) seriously, imagine a cannon ball shot horizontally. as it slopes downwards, sooner or later hits the surface. but what if you fire it fast enough, so as it bends downward, it just follows the curved surface? it will fall forever, but will never actually get any closer. like a dog chasing its tail.
- edward long 100+
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  Feb 22 2013: Right on! If you fire it from Earth and make it go fast enough (Escape Velocity) it will overcome the Earth's gravitational pull sufficiently to go right through Earth's atmosphere off into space where it will either continue moving away from Earth, or finally slow-down enough to settle into a state of eqilibrium called an orbit.
  - Mary M. 100+
    
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    Feb 22 2013: Thanks Ed.
    
    Have you seen the ISS up over Arizona?
    
    The night sky there can be so clear.....perfect for observing the skies at night.
    - edward long 100+
      
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      Feb 23 2013: We have a good astronomy club that hosts monthly star parties at the local observatory. Those folks enjoy the ISS very much. At some point in the evening one of them will announce, "Watch bearing 190 and azimuth 75 (high in the Southern sky) in two minutes there will be an Iridium Flare." And sure enough there is a sudden bright light reflecting off a satellite, very dramatic. Some of them have taken photos of the ISS through their telescopes. Rumor has it one amateur got a photo from Earth showing an astronaut working outside the space station in orbit! Fantastic stuff.
  - Mary M. 100+
    
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    Feb 23 2013: Wow Ed!
    
    How cool to be at one of those star parties.
    
    Several times in the past when we have driven through the darkness of the Everglades I stare out the car window in awe of the stars. Sadly though we have so much light coming from all the cities along the coast that the view is not so good, but at least it is much better than from our front door.
    
    There is a site where you can see the time lapse photography from a station in Chile where they observe the Milky Way.......really beautiful. I learned about it through one of the TEDster's comments on the talk above. It's worth a visit.
    
    The best view of space I've had has been from the island of Hispanola......saw the Milky Way while up in a mountain riding a motorcycle.......almost fell off too!! The site was so incredible.
- Mary M. 100+
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  Feb 22 2013: Thanks for that explanation.
  
  I really want to know how it varies in orbit.
  
  Because sometimes it's orbit takes it above Florida, and sometimes it doesn't.
  
  Does this have to do with the tilting of the earth? Or do they program the station to move?
  - Krisztián Pintér 200+
    
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    TED Translator
    
    Feb 22 2013: no it has to do with tilting, but not of the earth, but between the satellite orbit and the equator. and it has to do with the fact that you can't fill the day with orbital periods. it takes about 93 minutes to go a full circle. that means it makes 15.6 circles a day. because of that 0.6 at the end, after exactly 15 orbits, the ISS returns to the same point. but the earth did not manage to get there just yet, it still has a little to go to finish its first turn. but the ISS won't wait of course, and it starts to sweep a line over a different area, parallel to the one yesterday.
    - Mary M. 100+
      
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      Feb 22 2013: ok, I'm not understanding.......I read your explanation several times :P
      
      If it doesn't have to do with the earth's tilt then shouldn't the orbit be always over the same line the entire 15.6 circles......or are you saying that because the earth is also moving (rotating) then this affects the iss?
      
      Explain to me what does the equator have to do with it.....is it it's protrusion...or the magnetic fields of north and south pole....or what?
      
      Thanks for your patience....I am really trying to understand to be able to explain it to my kids.
  - Krisztián Pintér 200+
    
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    TED Translator
    
    Feb 22 2013: it has nothing to do with anything outside earth, and it is pure geometry, nothing else is involved.
    
    imagine a strange merry-go-round that has two rings, one inside the other, and they are at an angle to each other. they only meet in two points. also, the two rings are not rotating at the same speed. kids touch hands. then they go around, but one will complete a circle sooner, so they won't meet again. the same kid in the inner circle will touch hands with a different kid on the outer circle.
    - Mary M. 100+
      
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      Feb 22 2013: I was really lousy at geometry.
      
      But, I am going to reread your explanations, and think and draw and hopefully I will figure it out and be able to explain it to the kids.
      
      Thanks.
  - edward long 100+
    
    +1
    Feb 23 2013: Here's an excerpt from Science Officer Ed Lu's's email letter to Earthlings from aboard the ISS:
    ". . . our orbit hoop slowly rotates due to the fact that the Earth isn't quite a perfect sphere. This turns out to apply a torque to our orbit which makes it slowly shift westward with respect to the sun . . . It is the same effect that makes a spinning top wobble. In effect our orbit is like a large top, and the fact that the Earth has a bit of a bulge around the equator causes our orbit hoop to wobble slowly."
    - Mary M. 100+
      
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      Feb 23 2013: AHA!
      
      That is exactly the explanation I needed.
      
      So Krisztian mentions something about the equator.......and geometry....but here Ed Lu does a fabulous job of explaning it. Now I can even due a simulation with a top, great!!
      
      Thanks Ed.......let me give you a telescope and call you an astronomer :D
Krisztián Pintér 200+
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TED Translator

Feb 22 2013: sure, i have seen it many times. okay, not that many, but at least 3.
- Mary M. 100+
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  Feb 22 2013: cool!! did the travel time across the sky vary each time?
  
  How did you know to look for it?
  - Krisztián Pintér 200+
    
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    TED Translator
    
    Feb 22 2013: it moves at a constant speed, so the time is dependent on the path it travels. the best you can get is like half the sky, so it rises, slowly goes to the top, and then suddenly disappears. disappears, as it enters the earth's shadow.
    
    first time we were just sitting on a balcony, and saw something moving. later i used the heavens-above website to know beforehand when to look. it also tells you where to find, and how bright it will be.
    http://www.heavens-above.com/
    important! you have to set your location with the Configuration / Current observing site.
    - Mary M. 100+
      
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      Feb 22 2013: yep....we have seen it where it goes over close to the horizon and lasts only a minute. And we have seen it where it cuts our night sky in half and lasts close to 3 minutes going across.
      
      There's a site we use that tells us the exact time it will be passing over us, and from which direction it is coming, and how long the path will take.
      
      My son is so fascinated by it, especially since we visited the Kennedy space center last year.
      
      It would be really cool to go up on the shuttle and stay at the station a few days.
      
      I wonder how big they can get it to become.
  - Krisztián Pintér 200+
    
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    TED Translator
    
    Feb 22 2013: if he is so into it, and you won't mind a little trip, i highly recommend catching an iridium flare. iridium flares are ISS sightings on steriods, for hikers.
    - Mary M. 100+
      
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      Feb 22 2013: I will look this up as well. Thanks
      
      Here is the link we use, you just click the location and it will give you the dates and times it is visible:
      
      http://iss.astroviewer.net/observation.php
  - Krisztián Pintér 200+
    
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    TED Translator
    
    Feb 22 2013: heavens-above is better. it gives you a sky-map too. so you can locate the constellations it will cross beforehand.
    - Mary M. 100+
      
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      Feb 23 2013: I noticed that it has much more information on it......it's a great site.
      
      I'm going to share it with a friend of ours who is an amateur astronomer.

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