What Time is It, Satellite Time?
About GMT (Greenwich Mean Time) and UT (Universal Time)

The satellite gives times to scientists according to Greenwich Mean Time (GMT). GMT is an international time-keeping standard. It is based on the local time in Greenwich, England. Greenwich Mean Time is also called Universal Time (UT).

When measuring time with GMT or UT, it's the same time everywhere on earth! That's why it's considered "universal time."

Right Now...
You can think of these time measures as a way to specify the concept of RIGHT NOW--an exact moment in time, everywhere on Earth.

GMT was invented to avoid the confusion that using "local" or "solar time" causes when referring to events that are taking place in different time zones.

Local Time is Meaningless to a Satellite
Remember, the satellite is zooming around the earth every 101 minutes, so local times on Earth are a blur.

So what time IS it where the eagles are, local time? After all, local time DOES matter to an eagle whose behavior is regulated by earth's day/night cycles. Because the eagles are in the Eastern Time Zone, they are 5 time zones to the west of Greenwich, England. This means that local time for our eagles is 5 hours EARLIER than Greenwich Mean Time.

Related Links

Teacher Tip: World Clocks
Time zones can be difficult to visualize and understand. With the help of a few inexpensive clocks, this activity helps students compare and contrast what is going on right now in different times zones around the world.

Does The Sun Really "Rise" and "Set"?
What brings the sun's light to your town each morning, and brings darkness each night? These sample images of Earth taken from space show the location of sun's light at various times.