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.
Elizabeth said,
August 11, 2008 at 5:54 am
That is so cool!
What I Learned Today » Blog Archive » Colors of the Aurora said,
August 15, 2008 at 4:02 pm
[…] Unlike the International Space Station, the aurora remains a sky phenomenon that I have yet to witness with my own eyes. Yet I have read about and seen glorious images of the colored curtains of light, shifting suspended over arctic landscapes. While often yellow or green, some auroras are red or even purple (and some occur in the UV, not a “color” we perceive visually). […]