Update 2015: This page provides details for the 2014 Christmas Eve fly over of the ISS. For 2015 information please click here for the new page.
How wonderful would the look on a young child’s face be when they see Santa flying over your house on Christmas Eve? How you ask? A little bit of astronomy and the International Space Station can make it happen.
For those of you based in the United Kingdom there will be two passes of the International Space Station this Christmas Eve. While the times are for London, the ISS can be seen from the whole of the UK at approximately the same time. The first pass begins at 17:18 and will be 10 degrees above the horizon in the west at 17:20. The station will Pass through the distinctive “Summer Triangle” stars of Vega, Deneb and Altair before reaching peak brightness of magnitude -2.3 which is brighter than any star at 17:23:40, south west of the Great Square of Pegasus. The station will continue to transit across the sky, finally vanishing into the Earth’s shadow at 17:27. As the station is heading from the west to the south east you can explain Santa is flying to the children in “Asia” etc where it is already nearly Christmas. Below is a star chart with a plot of the ISS pass overlaid.
The second pass of the ISS occurs approximately 90 minutes later but is far less favourable. The ISS rises at 18:56 and reaches a peak altitude of only 12 degrees above the horizon in the constellation of Aquarius at 19:00 before vanishing in the Earth’s shadow less than a minute later. Peak brightness is a far less impressive magnitude -0.2. So if you can, try to see the first pass.
If you have not seen the International Space Station before, what you should you be looking for? The station appears like a bright star that slowly moves across the sky and could easily be mistaken for an aircraft (though there are no navigation lights flanking the main white light) by anyone unfamiliar with the appearance of the ISS.
For the young ones in your family, this could make Christmas just a little more magical. And for any slightly older children, why not inspire them by telling them that bright slow moving light in the sky is a Space Station the size of a football field which took 115 separate space vehicle visits to construct, travelling at 17,200 mph (27,600 kmh) at a height of approximately 270 miles (430 km) above the Earth’s Surface with over 1.5 billion miles on the clock and is currently crewed by Elena Serova, Barry Wilmore, Alexander Samokutyaev, Anton Shkaplerov, Terry Virts and Samantha Cristoforetti?
The ISS orbit is currently favourable for evening flybys for a large part of the dense population centres of the world. For example there is favourable pass of the ISS over the north east US at around 17:00 ET. If you wish to see what time you should be outside, please go to Heaven-above.com and enter you location via the “Change your observing location” link, either manually by placing a cursor on the world map or search for your town/city and then select 10-day predictions for Satellites of special interest “ISS.”
Fingers crossed for clear skies and a very happy Christmas.