How bright is the International Space Station? / La magnitud visual (o brillo) de la Estación Espacial Internacional

Strangely enough, the Wikipedia page on the International Space Station doesn't have any information on its magnitude, and I didn't notice any on the pages in some other languages either. There was however an article on Space.com in 2006 that claimed that the ISS is usually around the same magnitude as Venus (don't forget that it moves about and reflects light depending on the angle so the magnitude varies quite a bit), and since then there have been quite a few new parts added to it. The parts that are the brightest are the solar panels, and there is still another set of them to go up next year, along with a ton of other smaller components.

Yesterday there was another article on Space.com about spotting the space station, that has the following:

If you're out watching the twilight sky in the time frame from 45 to 90 minutes before sunrise, or 45 to 90 minutes after sunset, you'll might see a few "moving stars." They are most likely artificial satellites.

The brightest of all is the International Space Station, and this month provides some great opportunities to see it from just about anywhere.

Then some more info on its current and future size (I changed most numbers to metric here):

The International Space Station (ISS) is by far the largest and most brilliant of all the man-made objects orbiting the Earth. In early June, the station got its biggest live-in addition yet, a billion-dollar Japanese lab stretching 11.3 metres, named Kibo, which means "hope." Currently more than four times as large as the defunct Russian Mir space station, the International Space Station — when fully completed — will have a mass of about 520 tons. It will then measure 109 metres across and 88 metres long, with almost an acre of solar panels to provide electrical power to six state-of-the-art laboratories.

Then it gets into a lot more detail on exactly how to spot the space station. Here in the centre of Seoul is about the worst place in the world to spot the space station - it's always cloudy, the air is rarely clear, buildings are high. Viewing it in Calgary (Canada) back in 2004 was much easier. Knowing where to look last year though I was able to see Venus quite a bit just after the Sun went down, so perhaps I should try a bit harder to keep an eye out for the space station. Considering that it's brighter than Venus it's certainly not impossible to see even here.

One of the best parts of the ISS in fact is that it can be seen so easily, and will be able to be seen even easier in the future. It's always good to have a reminder to everybody down here that there are actually things going on up there 24 hours a day, and if you know where it is it's fun to surprise the person you're with by pointing up at the object on the horizon and casually mentioning that the super bright point up there is actually three people inside 520 tons of metal orbiting the Earth.


Lastly, I just found a page in Spanish with some information from 2004 on its exact magnitude:

La magnitud visual de la Estación Espacial Internacional es considerada a menudo como un brillante menos 0.9, aunque a su máximo brillo puede llegar a exceder este nivel y algunas veces parece llegar a rivalizar con Júpiter en brillantez.

(The visual magnitude of the International Space Station is often considered to be 0.9, although its maximum brightness may exceed this leval and sometimes seem to rival Jupiter in brilliance.)

How big was it then? Here's the size then, so comparing it to now (58.2 metres and 277,598 kg) should provide a good idea:

La Estación Espacial Internacional es con mucho, el mayor y el más brillante de todos los que circundan el planeta... Los módulos principales tienen juntos 45 metros de longitud. Se mantiene tan alta como un edificio de nueve pisos y pesa 186,900 kilogramos.

The International Space Station is by far the largest and most brilliant of those that circle the planet. The principal modules are 45 metres long. It is as high as a nine-storey building and weight 186,900 kilograms.