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Sunrise
Daylight
Sunset
TST-MST
STD-MST
LDT-MST
LDT-STD
LDT day

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Explore six different time keeping systems across location and date. How are they different? When is sunrise? Sunset? How do these vary with the seasons? With latitude? What does each clock say? What time should it be? Where are the time zone boundaries? Where were they originally? Are they necessary? Where is daylight saving time used and when does it change? Is that sundial correct? Does sunrise vary at the equator? How far away from the equator before the sun doesn't rise and set every day? Find the answers for yourself using this web page.

"For the natural days
are truly unequal,
though they are
commonly considered as equal
and used for a measure of time"
Isaac Newton

Tooltips explain all of the controls and calculations as you move the cursor over them. The button in the upper left opens a dialog to search the map and save your favorite locations. Changing these allows rapid comparisons of time in different places. The date can be changed easily to find the longest day, latest sunrise, or any other peak or valley in the numbers. The map center can be moved in many ways, by panning, dragging the red marker, using the hand, or changing your saved locations, shown with blue markers. Click on time zone boundaries to display links to time information. All time calculations are immediately updated by clicks or arrow keys.

© Copyright Keith Thomas 2014