Another good opportunity to watch the International Space Station fly over Maryland occurs Thursday. With clear skies in the forecast and the spacecraft expected to be particularly bright, it could be a very good show.
Look for the spacecraft to appear over the southwest horizon at 7:35 p.m., rising about three-quarters of the way up the sky as it moves to the northeast. It will appear as a light brighter than a star but appearing much more distant than a plane, moving swiftly and steadily across the sky.
The ISS will "set" at about 7:41 p.m. in the east-northeast sky.
The ISS is expected to be brighter than the brightest star and almost as bright as some planets appear in the night sky.
The typical "magnitude" of the ISS is -2 on an ancient Greek scale of celestial brightness, compared with -1.44 for Sirius, the brightest star, and -4.4 for Venus (the lower the value, the brighter the object, according to Heavens-Above.com).
Thursday's appearance of the ISS is expected to register a -3.4 magnitude, much brighter than normal. Skies are forecast to be clear throughout the day and night Thursday, so clouds shouldn't obscure the show.
On board are NASA astronauts Sunita Williams and Kevin Ford, three Russian cosmonauts and a Japanese astronaut. Williams, the current mission's commander, frequently posts photos and other updates on Twitter, so follow along.