The International Space Station and my Naked Eye
August 7th, 2008 at 9:14 pm (Spacecraft)
I saw the International Space Station with my own eyes for the first time today. It crossed over Los Angeles from about 8:52 p.m. to 8:57 p.m. (You can get a list of upcoming local flybys based on your zip code.) It was bright: magnitude -3.0, according to that website (“magnitude” of sky objects is inversely proportional to brightness). I watched it sail overhead, from the northwest towards the southeast. It was a solid light, moving so quickly that you might mistake it for an airplane, but then it became obvious that this was no low-altitude craft.
It was nearing Jupiter (within about 8 degrees by my estimate) and I was comparing their brightness. At first, I was sure it was brighter than Jupiter (which, my StarPilot software claims, is -2.6 magnitude, so that checks out). But then it started to get dimmer. I blinked, but I wasn’t imagining it. It got dimmer and then began to turn red, and as I watched, it entirely vanished!
Some quick geometric reasoning suggested that I did not just witness the fiery demise of the ISS. Instead, it must have crossed into the Earth’s shadow while I was watching. Given the time of day and the relative position of Sun, Earth, and ISS, that makes sense. The red color I would not have known whether to expect to see visually, but presumably it’s the same effect we see at sunsets: low-angle sunlight must cross through more atmosphere, absorbing more of the shorter-wavelength colors, and at the limit, red will preferentially shine through due to refraction even as the Sun is partly occluded. So the light I was seeing definitely wasn’t coming from some airplane’s headlight; it was reflected sunshine!
And not only did I see the ISS, but I witnessed an ISS eclipse.