The shuttle undocked from the international space station earlier in the day on Tuesday after installing new solar panels during its mission.
The shuttle passed over the Colorado skies at 10:04 p.m. and the crowd at the Chamberlin Observatory, not far from the University of Denver, did not want to miss it.
Dr. Steven Lee is a curator at the Denver Museum of Nature and Science and he was one of those at the Chamberlin Observatory Tuesday night.
He says the fascination of space still makes him feel like a little kid sometimes and Tuesday night was one of those times.
"You'll be able to see both the space station and the space shuttle fly overhead," said Lee earlier in the evening.
The shuttle is still close to the space station, as astronauts perform safety checks for any damage. If they find a problem, they can re-dock with the space station and repair it.
From the ground in Colorado, the 46 miles between the shuttle and the space station was only about the width of a thumb.
"They'll be moving in tandem, lock step moving across the sky," said Lee. "It is a very rare event to see here in Denver right after the shuttle undocks."
The shuttle appeared about three fists up from the horizon and scientists said it was much brighter than Venus.
Among the astronauts coming home is University of Colorado graduate Steve Swanson. He was one of two crew members who activated a new joint installed on the station during a spacewalk over the weekend.
Atlantis is scheduled to land on Thursday, just before noon Mountain time. If needed, the shuttle has enough fuel to last until Sunday.
Click here to visit NASA's Web site for updates on the mission.
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