Satellite Picture: When Was It Taken?
Satellites take many pictures. How do you know you are looking at the most recent one? How long ago was the picture taken? Most satellite images have the time written on them, but it is in a form that may be difficult to read. Here is a guide to finding the time.
As you know, there are many different time zones around the globe. The one generally used on satellite images is universal time (U.T.), also known as zulu time (Z), and Greenwich mean time (GMT). All three refer to the time in London along the Greenwich Meridian. When a satellite picture is taken, it is logged according to traditional military notation for time (that is, the 24-hundred hour notation). So if you see a picture taken at 0830 Z, this means it was taken at 8:30a.m. zulu time. You can use a chart to convert a U.T., Z, or GMT time to the zone where you live. Photo: Courtesy of NASA
To convert to standard time in North America, subtract the appropriate number of hours from the chart below. To convert to zones outside North America, use the U.S. Naval Observatory's World Time Zones page or try Burbs time zone converter.
|Newfoundland zone||3.5 hours|
|Atlantic zone||4 hours|
|Eastern zone||5 hours|
|Central zone||6 hours|
|Mountain zone||7 hours|
|Pacific zone||8 hours|
|Most of Alaska||9 hours|
|Hawaii and Alleutian Islands||10 hours|
To get daylight saving time, subtract one hour to your answer. Thus, if the satellite image was made Friday at 1500 hours (fifteen hundred hours) Greenwich mean time, then the time on the East Coast of the United States was 1000 hours (10 hundred hours). If daylight saving time was in effect, subtract one hour.
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