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Credit: Terry Renna, AP
A record one million spectators are expected to be at or near NASA's Kennedy Space Center this week to see the historic last launch of the space shuttle Atlantis.
But for those who can't make the trip to Florida, the upcoming STS-135 mission marks the last time sky-watchers around the world will have the chance to see a shuttle passing above their backyards.
(Video: "Space Shuttle's Final Days.")
Depending on where you are on Earth, both Atlantis and the International Space Station (ISS) should be visible to the naked eye during the mission, which is scheduled to last for 12 days.
When skies are clear, Earthbound viewers generally see both the shuttle and the ISS as fast-moving "stars." The spacecraft are easy to spot, because they're among the brightest objects in the night sky.
Even while Earth is cast in shadow, the orbiting objects are being hit by direct sunlight, which reflects off their shiny, metallic surfaces.
Still, knowing exactly when and where to look is crucial: The spacecraft are moving at about five miles (eight kilometers) a second, and they'll cross the sky in just a few minutes.
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