This view of SpaceX's first Dragon spacecraft to the International Space Station was captured by Expedition 31 astronauts during the capsule's first flyby on May 24, 2012.
A private space capsule is set to arrive at the International Space Station, and tonight may be your last chance to spot it in the night sky during the mission, NASA says.
The unmanned Dragon space capsule built by SpaceX launched toward the space station early Tuesday on its maiden voyage to the orbiting lab. It is the first commercial spacecraft ever to visit the space station and if all goes well, Dragon will arrive at the outpost early Friday (May 25).
That means that between now and tomorrow (Dragon is slated to be attached to the station at 11:03 a.m. EDT, or 1503 GMT), skywatchers that have good weather and know where to look may get a chance to see Dragon flying overhead as a moving light accompanying a brighter light— the International Space Station.
"If you've never seen the space station, it is quite dramatic to see, it can be the brightest thing in the night sky after the moon," NASA spokesman Josh Byerly said today after Dragon flew by the station in a test run. "Some of the passes last upwards of three of four minutes."
Satellites in space appear as moving lights because, like the moon, they still reflect sunlight from orbit over locations where it is night. Photos of Dragon by the space station crew show it to be a gumdrop-shaped capsule with two solar arrays unfurled. [SpaceX's Historic Flight to Space Station (Photos)]
If Dragon is successfully attached to the space station on Friday, then its light will be outshined by the station's glare, making it impossible to see with the unaided eye. Veteran satellite trackers equipped with the right telescope and tracking gear may be able to see the space station in more detail.
However, Dragon is currently expected to leave the space station on May 31 and splash down in the Pacific Ocean on the same day, meaning it may likely much more difficult to see in space as it is now.
"This is a very historic flight for SpaceX, so obviously if you get a chance we encourage you to step outside and see Dragon and the space station flying over your hometown," Byerly said.
There are several ways to find out when Dragon and the space station will be flying over your location. First you can check out these three websites:
Each site asks for your zip code or city, and responds with a list of suggested the most optimum spotting times. Predictions that are generated a few days ahead of time are typically accurate within a few minutes. But, occasionally they can change so be sure to check frequently for updates.
Another good website is Real Time Satellite Tracking, which shows what part of the Earth the space station and other spacecraft happen to be overhead at any given moment during the day or night.
The Hawthorne, Calif.-based SpaceX has a $1.6 billion NASA contract to provide 12 Dragon flights to deliver supplies to the space station. This mission is a trial run for that contract. SpaceX is one of several commercial companies aiming to fill NASA's space transportation needs now that the agency's shuttle fleet is retired.
Editor's note: If you snap amazing photos of the Dragon capsule in orbit that you'd like to be considered for use in a story or gallery, please send pictures and comments to SPACE.com managing editor Tariq Malik at firstname.lastname@example.org.