You may notice that some sundials show only 12-hour measurements, since they won’t work for the hours that the sun is down.
The 12:00 noon notation is aligned with the gnomon, so it will be pointing north as well.
To find the Southern Cross, look for 4 stars shaped like a small kite. The farther south you are, the higher it will be in the sky. [3] X Research source
At the equator, the sun rises along the eastern horizon and moves straight up, then sets on the western horizon. If you used a horizontal sundial, the shadow would fall mostly west in the morning and mostly east in the afternoon, instead of rotating slowly.
You might see different line denotations based on your sundials, but it should be split into even sections by 5 minutes or 10 minutes so you can get an accurate estimate.
For example, Pacific Standard Time (PST) is 8 hours behind GMT. Multiplying 8 hours by 15° gives you 120, so PST’s center longitude is 120° West. You can find the current GMT time by searching online.
For example, Seattle is at 122. 3° West longitude. The central longitude of its time zone (PST) is 120° West, so Seattle is 2. 3° away from it.
In Seattle, for example, you’d multiply 2. 3 by 4 to get 9. 2. Since Seattle is west of the time zone’s center, sundials in Seattle are 9. 2 minutes behind clock time, so you need to add 9. 2 minutes to make them equivalent. If your sundial reads that it’s 1:40 pm in Seattle, then, you’d add 9 minutes to estimate that it’s 1:49 pm. Why 4 minutes? Since most time zones are 15° of longitude wide, or 1 hour long, you can divide 60 minutes by 15° to see that it takes about 4 minutes for the sun to move through 1 degree.
Search online to see when Daylight Saving Time starts and ends in your region.
Most calculators require you to enter in your year and longitude or time zone. The calculator will then give you a table telling your how to adjust your sundial time throughout the year. [10] X Research source
