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Video Transcript:

What Time is it in Space?

Alexandra: Earth is generally divided into twenty-four time-zones of an hour each. This division helps us sleep while it's dark, and keeps breakfast around sunrise.

As the International Space Station orbits Earth, astronauts on-board see a sunrise about every hour and a half, and it's almost a month between each sunrise on the Moon. So how can you tell when it's time for breakfast during your space mission?

The first thing to keep in mind is that time is relative, so whether you’re orbiting Earth or going to the Moon, you need a reference point for your time.

Greenwich Mean Time, one of those twenty-four time zones (Map highlighting the location of the time zone for which Greenwich Mean Time is determined, and break-out map of England showing the location of Greenwich, England), is the reference point on Earth. NASA uses GMT to mark when events happen during a mission. NASA also uses Mission Elapsed Time or MET during space missions (Video showing the Mission Control Center and mission clocks). MET clocks start counting forward from the moment your ship lifts-off.

As long as everyone agrees which clock to use, everyone knows when it's time for breakfast.

Take some time to explore space at NASA.gov .

 
Feedback/questions: brainbites@nasa.gov

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 12/07/2004
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