While perhaps not as photogenic as their natural cousins, artificial satellites do have a fascination of their own due to their very rapid motion across the sky. Watching a bright dot move swiftly and silently among the stars is something that mankind has only been able to do for the last 50yrs, and the sheer number of such travellers visible on a dark night reminds us of the great progress that has been made in space science in that half century.
However, most satellites are quite dim objects because although they are very near to us they are also extremely small by planetary standards. This means they have limited observational interest, so I did not bother with them until my attention was drawn to an upcoming series of near-overhead passes by the much-enlarged International Space Station (ISS). I was aware this was visible from the UK on occasion but with the addition of a series of solar-cell arrays its brightness has increased many-fold, turning it into a really dramatic object able to out-shine Sirius, the brightest star in the sky, by a factor of almost 7 times. Not only that, its closeness to the Earth (just 210mls up) means it moves across the sky very quickly - no more than 6mins from horizon to horizon. I just had to get the camera out! To learn more about ISS visibility, click here.
Given the brief visibility of the ISS, knowing when to look is of course rather important! Daily predictions for any location are given on several Internet websites, such as heavens-above.com, and I soon became interested in the other satellite phenomena also listed there. Photographically, Iridium flares looked the most intriguing as they are bright (sometimes extremely so!) and short-lived thus providing images that are more than just a uniform faint streak. But what, I hear you say, is an Iridium flare? It is a reflection of sunlight from one of the many satellites providing communications services for the Iridium Corporation. Any satellite can reflect sunlight of course but Iridium satellites are particularly likely to do so - to find out why, click here.
Pictures of both the International Space Station and Iridium flares may be found in the Artificial Satellites chapter of the My Astrophotographs section of the Space Picture Gallery.
