Have you seen the International Space Station?

International Space Station against the Earth
Image: NASA 

The International Space Station (ISS) regularly flies over Melbourne (and all parts of Australia). It appears like a bright dot, travelling quietly and without any flashes and can take more than five minutes to travel from horizon to horizon. You can use smartphone apps or websites that will alert you when it’s going to go overhead. It’s probably best viewed with your eyes, but a pair of binoculars will make it more spectacular, allowing you to see more stars as the ISS sweeps past them.

This blog will show you how to recognise the ISS, tell you what it does, how to find out when it’s coming over, and how to see it best.

International Space Station facts

  • Visited by over 220 astronauts since 1998
  • Needs an occasional push to keep it up
  • Useful for all sorts of experiments
  • Looks spectacular against the Moon or the Sun

The International Space Station is celebrating its 20th anniversary. Its first parts were launched 20 November 1998, and it’s grown since then, with several countries attaching new bits. It’s also been visited by over 220 different astronauts, including Australian-born Andy Thomas, who’s been there twice.

The ISS orbits the Earth at a height of between 330 and 430 km. Even at this height, there’s just enough atmosphere to slow it down and drag it back, so every so often it needs a boost to get it back up again. The NASA engineers use a separate propulsion module for this, and call the operation “altitude maintenance“.

The ISS serves as an orbiting platform for all sorts of scientific experiments that need near-zero gravity. This includes heaps of experiments on plants, insects and liquids, as well as experiments that look at meteorology (by looking down on weather patterns below) and astronomy (by looking upwards at stars and planets).


International Space Station against the Earth
Image: NASA 


Occasionally people take photos of the ISS as it passes in front of the Sun or the Moon. I particularly liked this one. It’s a very difficult photo to take, as not only is the ISS 400 kilometres away (nearly as far as Melbourne to Canberra) it’s also moving at about 28,000 kilometers per hour! Not only do you need to know exactly where it’s going to be and when, but you need to take a super-fast photograph to avoid blurring. It takes less than a second for the ISS to cross the Moon’s face.

International Space Station against the Moon

Image: NASA 

Seeing the International Space Station yourself

Tracking the International Space Station is easy if you’re looking out for it. Of course, it helps to know if there’s a fly-past coming up. It doesn’t need to go directly over your head, either. It’s high enough for you to be able to see it a long way to the left and right of its path. In fact, when the ISS is above Alice Springs, everyone in Australia can see it, even though for people in Melbourne and Perth it’d be pretty low to the horizon.

The ISS is as bright as Venus. It moves across the sky in about five minutes, but doesn’t have strobe lights that flash like an aeroplane (and you certainly can’t hear it). Because it’s so much bigger, it’s also brighter than other satellites. What’s more, it doesn’t spin like other satellites so it doesn’t vary in brightness.

How to see it best

Believe it or not, the ISS is great just with your eyes. After all, it’s the third brightest thing that can be seen in the sky (after the Sun and the Moon, of course). If you want a better look, I’d recommend a pair of low magnification, high light-gathering binoculars, like the saxon Expedition 8×42 Binoculars, or the Celestron Skymaster DX 8×56 Waterproof Astronomy Binoculars. This type of binocular can give you an excellent sense of context, as they will pick up stars as the ISS glides past them. You probably won’t see many stars with your eyes, especially if you’re in a city like Melbourne.

Celestron Skymaster DX 8×56 Waterproof Astronomy Binoculars saxon Expedition 8×42 Binoculars

Tip: you might find that it’s hard to locate the ISS in your binoculars. If that’s the case, put the binoculars down and just enjoy watching it pass. You’ll be disappointed if you spend all the time hunting and never actually watch it.

How to know it’s coming

Of course, in order to see the ISS, you’ll need some advance warning. There are a few ways of finding out when it’s coming past.

Websites will show you the orbit and its current location on a map. My favourite is Heavens Above. This is an excellent website which I’d encourage you to explore, as it shows you a lot more than just the ISS. You’ll have to tell it your location first, and then it’ll be able to tell you about flybys over the coming weeks. The best ones are those shortly after sunset, which is when the ISS is brightest. The ISS doesn’t have big lights on it, but it does fly high enough for it to be in the sunshine after sunset for people on the ground.

Of course, NASA has its own website, called “Spot the Station“. It works in the same basic way, but if you sign up, NASA’s website is able to send you an email or an SMS when there’s a flyby coming up.

If you’ve got a smartphone (duh: we all have) there are a few apps that will alert you when the ISS is about to go over. They work in a similar way to the websites, but most are clever enough to get your location from your phone, making the whole process that much easier.

Can they see you?

Well, kind of. They can certainly see big cities. But it’s better than that – you can see live views from the ISS, as long as it’s on the sunny side of the planet. Go to NASA’s High Definition Earth-Viewing System, or search for “NASA Live: Earth Views from the Space Station” on YouTube.

Your own photos?

Without getting too technical, it’s possible to take your own really cool photos of the ISS as it passes overhead. I took this time exposure a couple of years ago with a standard DSLR and a tripod. The ISS went nicely between the Southern Cross and its Pointers (I wish I could say I’d planned it like that). The photo is actually four 30 second photos all put together in Photoshop. The ISS shows up as a bright line across the sky, while the stars only move a tiny bit. That’s part of my house in the foreground.

International Space Station over East Kew

Recommended reading

NASA’s International Space Station page

International Space Station – Facts and Figures

ISS’s own blog

Bill is Optics Central’s expert on astrophotography, telescopes and bird watching. You’ll find him in the Mitcham store on Fridays and Saturdays. Come in for advice on how to get the best out of your current telescope, what your next telescope should be, how to take photos of the sky, or even how to see some rare birds.

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