International Space Station can reach magnitudes of up to -8.0

Going to a castle to photograph the ISS? I'm jealous.

Spaceweather.com has a nice bit today about the magnitude the ISS is capable of reaching now that it has its full complement of solar panels and is capable of flaring up in brightness all of a sudden as it shifts in angle and reflects the Sun's light in different ways. They have an image here sent in by a reader of the site that shows how the magnitude can change as it crosses the sky.

As for how bright -8.0 is:

"At maximum, the ISS reached magnitude -8," he estimates. That's more than 25 times brighter than Venus or 400 times brighter than Sirius, the brightest star in the sky. "I photographed the flare using my Canon 30D and an all-sky mirror."

The Moon at its brightest reaches a magnitude of up to -12.6, and -6 when a crescent, so the ISS is now easily capable of being even brighter than a crescent Moon.

In addition to that, though no more solar panels will be installed the ISS is still going to grow larger than it is now with the addition of such parts as Tranquility (Node 3), the Japanese Exposed Facility, and others.