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The sundial and clock agree four times a year, on or near April 15, June 15, September 1 and December 25. I haven’t found any special names for these dates. No equinox or solstice label to mark these days.

That surprises me because I imagine that ancient people who were so observant of the Sun and Moon that they built temples to their movements would have noted these days. If you were a priest or in the upper class, you could have a large or small temple or altar that marked the astronomical events in an earthly way. But for the average person, I am imagining that a simple sundial was your most likely way to mark the time and follow the Sun.

At this time of the year, when the midday sun is highest, your sundial should say it is noon and your clock should say 12 pm.

I have always had a sundial in the garden. My mother had one in the garden when I was a kid and I have one now. It probably is one of the reasons that I still am tuned in to the Sun and Moon.

As a kid, it annoyed me that the sundial was always wrong. It was “wrong” because when it said it was 1 pm, I knew it was 2 pm because I had a watch. And I have always adjusted my sundial so that it was close to clock time.

I don’t know exactly when I discovered the why of the Sun’s path that explained the sundial but I was certainly an adult.

I am tempted to install a more permanent sundial in the garden, one that is wrong most of the year, as a reminder to me that the Earth is changing its relationship to the Sun.

A sundial can be as simple as sa stick in the ground that casts a shadow. That shadow from the style falls onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, the straight edge. As the sun moves across the sky, the shadow-edge aligns with hour-lines. Sundials need to have that edge parallel to the axis of the Earth’s rotation to tell the correct time throughout the year.

Long ago, people thought the Sun was moving across the seasons. Most people today (not all, I have discovered) know it is the Earth tilting and moving that cause the sundial to change.

You should pay attention to all the cycles in your life. Some are natural and some we create ourselves. They affect us, whether we pass attention to them or not.

Maybe you should get yourself a sundial and tune in to the Earth and Sun.

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One of my daily web stops is EarthSky which reminded me that this is one of the few times of the year that clock time and sun time agree. As someone who has a sundial in the garden since childhood, I do pay attention to that shadowy movement.

When the midday sun climbs highest today, if you have a sundial, it will read 12 noon and your local clock will also read 12 noon.

I have always had a sundial in my garden. It keeps me in touch with the movement of the Sun during the day and during the seasons.

Of course that pesky daylight savings time game we play might make your clock say 1 pm today when the sundial says noon. It’s all so confusing.

Your local clock time is standard clock time, as long as you live on the meridian that governs your time zone. Denver and Philadelphia, for example, are on the meridian for their respective time zones. East of the time zone line, then your local time runs ahead of standard time and west of the time zone line, local time lags behind standard time.

The sundial and clock only agree four times a year: on or near April 15, June 15, September 1 and December 25.

My simple sundial shows a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, the straight edge. As the sun moves across the sky, the shadow-edge aligns with hour-lines.

There are plenty of sundials available to you at a wide variety of prices and complexities. Sundials that directly measure the sun’s hour/angle must have that edge parallel to the axis of the Earth’s rotation to tell the correct time throughout the year. My simple one needs some adjustments during the year and I do play with time and move it to match my clock time every once and awhile.

Isaac Newton had a pretty interesting variation on the sundial. He used a small mirror placed on the sill of a south-facing window. The mirror would cast a single spot of light on the ceiling and, depending on the geographical latitude and time of year, the light-spot on the ceiling was pretty accurate to the markings he made.

I think it’s a good idea to pay attention to the cycles in our lives, both natural and man-made. They are very much a part of us, whether we pass attention to them or not.

Copernicus Armillary

I would not mind having a Copernicus Armillary (above) in my home, though I suspect my wife would not think it appropriate to our decor – and might not appreciate me paying $3000 for it. It is an astronomical instrument that would have been found in libraries and laboratories of the past. But I did find some online for less than a hundred dollars so maybe…

This post first appeared on One-Page Schoolhouse

sundial1

I have always had a sundial in my garden. It keeps you in touch with the movement of the Sun during the day and during the seasons.

My basic horizontal sundial shows a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, the straight edge. As the sun moves across the sky, the shadow-edge aligns with hour-lines.

Sundials that directly measure the sun’s hour/angle must have that edge parallel to the axis of the Earth’s rotation to tell the correct time throughout the year. The style’s angle from the horizontal should equal the sundial’s geographical latitude, but in most inexpensive sundials the hour angles are off and cannot be adjusted. There are many other types of sundials.

Isaac Newton developed a convenient and inexpensive reflection sundial using a small mirror placed on the sill of a south-facing window. The mirror casts a single spot of light on the ceiling and, depending on the geographical latitude and time of year, the light-spot on the ceiling was drawn large enough to be accurate.

Most mass-produced sundials are not the most accurate timekeepers, but in mid-April time by the sun and time by my clocks agrees. Noon is noon in both places.

I adjust my sundial as the months move past me, but I suppose that is a bit of a cheat. This weekend the length of the day as measured by the midday sun is slightly less than 24 hours long. This discrepancy between my watch and the Sun accumulates until mid-May when noon on my sundial will be a few minutes earlier than the clock. After that the sundial middays will become slightly more than 24 hours long and by mid-June, they will match up again.

Cycles. Very much a part of our lives, whether we pass attention to them or not.

 

Sundial Bridge, Redding Ca. The white pylon is 218 feet tall and the Sundial Bridge free spans 500 feet across the river. The Sundial is functional and the northern shoreline has markings with the summer solstice and time of day.

 

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