What Can You See in the Night Sky This Week?

31 January 2012 by Philip James Ma...

Every 90 minutes or so, the International Space Station orbits the Earth, it's six inhabitants watching over us as we go about our daily lives. In the dark before dawn or just after dusk, it can be seen crossing the sky - but in a few minutes, its gone again, back into the Earth's shadow. So how do you catch our man-made shooting star?

The International Space Station is an amazing feat of human engineering. Its solar panel array spans an immense 70 by 100-metre area (about the size of a football pitch), generating electricity for use by the crew living on board. Astronauts (and cosmonauts!) from Europe, Russia, America, Canada and Japan typically spend about 6 months at a time up there, manning and maintaining our most distant outpost. They carry out experiments on how things work in space: how the bodies of plants and animals respond to such low gravity, the kind of things we need to understand before we venture further out into the solar system. The station is in a low Earth orbit, just outside the atmosphere: for the crew of the ISS, the sun rises every 91 minutes! Just like down here on Earth, "night time" is when they are in the Earth's shadow, but just as if they were on a transatlantic redeye flight, their nights are shorter. The difference is that the ISS crew are constantly flying West to East around the Earth at 18,000 miles an hour! That's some jetlag.

The ISS' solar panels don't capture all the sunlight they receive during the ISS day: some gets reflected, and some of that reflected light gets reflected towards us. When it's night time for us (so the sky is dark), but when the sun is still up for the ISS crew, we can see it! It looks like a bright yellow star, moving about as fast as an aeroplane across the sky from West to East - if you are looking up at the right time, you can't miss it. The problem is: when to look up?

We know the orbit of the ISS very well (even without help from the people who put it up there!). This Friday (3rd February, 2012), you'll be able to see the ISS from Oxfordshire at 6:01:45am for about 4 minutes, low to the horizon from the South-South-West to the South-South-East! If you already have plans at 6am Friday, don't worry: you can use the CalSky website anytime to predict when the ISS will be visible, up to a few weeks in advance. Make sure your location is set correctly - and note that it uses the 24-hour clock!

You can also get daily alerts as to when the ISS will be visible, by following @twisst on twitter, and there's a lot of useful information about the ISS on the twisst website. You'll notice that the ISS is not visible every day: its orbit drifts around the Earth, so sometimes it is not reflecting light towards us at the times when it is dark enough for us to see it. However, this ever-changing orbit means that the ISS flies over most of us in the world in turn, so we all get to see it! And in turn, they get to see us: take a look at this incredible time-lapse video of the Earth as seen from the ISS.

If you're really keen, try taking a photo of it! (Practise on Jupiter first though, to make sure you have the exposure time long enough, and the camera fixed steady enough, to get a good picture.) There are a few ISS paperazzi out there who have made a hobby out of capturing the ISS in some unusual situations: check out the ISS in silhouette here and here. Do follow the links to Thierry Legault's astrophotography website: he has taken some mind-boggling photographs of one of the wonders of the modern world!

You can read more about the ISS, and find out what it's current occupants are up to, at it's mission home page at the NASA website - and you can keep up with it on the internet as well as in the garden, on facebook.

And don’t forget that if you want to know about other objects up in the night sky this week, visit the Blackett Observatory’s What’s Up page.

Categories: what's up | marshall | iss | stargazing | space station | astrophotography