Casis Gardens
Come explore the
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| Sundial |
Calculate Daylight Savings Time
| Stand on the current month |
| Mr. Springer marks the sundials "True North" |
The Casis Sundial offers a way to determine the time of day as revealed by your shadows position on it's surface.
In order to compensate for the earths tilt, you must stand on the correct month on the date line in the center of the sundial with
your arms stretched upward over head, palms together. This will cast a shadow near a number on the dial. Because the earths
orbit around the sun is not a perfect circle but an ellipse there are also additions or subtractions that will need to be done if you
want to be equal to clock time. When we are observing daylight savings time, in the late spring, summer and early fall, add
1hour to the time your shadow casts.
Because of the math component involved, the hour numbers have space to use chalk to make calculations for the
compensations above. A close proximity of time may be enough for your class. The sundial is a way to interact with the natural
world. How far you want to go with it is up to you.
Listed below are some further sundial facts…There are also many ways to tie history into the sundial as before the railroads
made their way across the country in the 1800’s sundials were used in town squares, gardens and by travelers for thousands of
years prior.
As a place to relax with your class in the gardens, to use as an outdoor amphitheater or a way to explore our world and solar
system from the suns perspective, enjoy it!
Below are some more Sundial facts and ideas!
The Casis Human Sundial
So now that we have one, what can we do with it? Measure time, of course, but many other things, too…
1. We can do simple addition and subtraction
2. Some multiplication, (x 4’s is a good one for our location, 7 degrees or so off our time meridian)
3. Make charts
4. Study the changes of the seasons
5. The tilt of the earth
6. The earth’s elliptical rotation around the sun
7. Basic earth related topics like latitude and longitude. (great topic and relates to the shape of our dial as well, the closer
to the Equator the narrower a sundials ellipse becomes, wonder why?)
8. North, South , East, West
9. The North Pole, or True North and why it differs from magnetic North
10. The North Star
11. Our solar system
12. The earth has magnetic poles, why? The earth’s core…
13. Directions
14. Maps
15. Shadows
16. Nature
17. History, many links here including the railroads, how people measured time before clocks…
18. We can do simple experiments, too
19. We can make observations
20. Predictions
21. Study and learn about inquiry
22. Learn to look at things from different perspectives
23. Compare Solar Time against Central Standard Time, (CST)
24. How would people tell time if it was not sunny or it was raining?
25. Problem solve
26. We can make simple sundial projects out of paper, string or plates
27. Look into what other things the sun affects
28. Dare we mention daylight savings time? It makes the sundial look really out of touch! Learning opportunity here!
29. Stand in our sundial and place markers where our shadows fall one at a time during gardening time and see a
progression.
30. Look at plants that bloom at different times of the day, plants that follow the sun like the sunflower.
31. Use it as a place to gather and hold an outdoor class project related or not to the garden.
Oh the possibilities!
Some basic Casis Sundial facts
It is an amazing teaching tool and an enjoyable space with a “bright” future at Casis.
OH, and one last thing…
“Time zones did not become necessary in the United States until trains made it possible to travel hundreds of miles in a day.
Until the 1860s, almost 150 years ago, most cities relied upon their own local “sun” time, but this time changed by approximately
one minute for every 12 miles traveled east or west. The problem of keeping track of over 300 local times was overcome by
establishing railroad time zones. Until 1883 most railway companies relied on some 100 different, but consistent, time zones.
That year, the United States was divided into four time zones roughly centered on the 75th, 90th, 105th, and 120th meridians.
At noon, on November 18, 1883, telegraph lines transmitted GMT time to major cities where authorities adjusted their clocks to
their zone's proper time.
On November 1, 1884, the International Meridian Conference in Washington, D. C., applied the same procedure to zones all
around the world. The 24 standard meridians, every 15 east and west of 0 at Greenwich, England, were designated the centers
of the zones. The international dateline was drawn to generally follow the 180 meridian in the Pacific Ocean. Because some
countries, islands and states do not want to be divided into several zones, the zones' boundaries tend to wander considerably
from straight north-south lines.”
Source: National Institute of Standards and Technology Physics Laboratory
In order to compensate for the earths tilt, you must stand on the correct month on the date line in the center of the sundial with
your arms stretched upward over head, palms together. This will cast a shadow near a number on the dial. Because the earths
orbit around the sun is not a perfect circle but an ellipse there are also additions or subtractions that will need to be done if you
want to be equal to clock time. When we are observing daylight savings time, in the late spring, summer and early fall, add
1hour to the time your shadow casts.
Because of the math component involved, the hour numbers have space to use chalk to make calculations for the
compensations above. A close proximity of time may be enough for your class. The sundial is a way to interact with the natural
world. How far you want to go with it is up to you.
Listed below are some further sundial facts…There are also many ways to tie history into the sundial as before the railroads
made their way across the country in the 1800’s sundials were used in town squares, gardens and by travelers for thousands of
years prior.
As a place to relax with your class in the gardens, to use as an outdoor amphitheater or a way to explore our world and solar
system from the suns perspective, enjoy it!
Below are some more Sundial facts and ideas!
The Casis Human Sundial
So now that we have one, what can we do with it? Measure time, of course, but many other things, too…
1. We can do simple addition and subtraction
2. Some multiplication, (x 4’s is a good one for our location, 7 degrees or so off our time meridian)
3. Make charts
4. Study the changes of the seasons
5. The tilt of the earth
6. The earth’s elliptical rotation around the sun
7. Basic earth related topics like latitude and longitude. (great topic and relates to the shape of our dial as well, the closer
to the Equator the narrower a sundials ellipse becomes, wonder why?)
8. North, South , East, West
9. The North Pole, or True North and why it differs from magnetic North
10. The North Star
11. Our solar system
12. The earth has magnetic poles, why? The earth’s core…
13. Directions
14. Maps
15. Shadows
16. Nature
17. History, many links here including the railroads, how people measured time before clocks…
18. We can do simple experiments, too
19. We can make observations
20. Predictions
21. Study and learn about inquiry
22. Learn to look at things from different perspectives
23. Compare Solar Time against Central Standard Time, (CST)
24. How would people tell time if it was not sunny or it was raining?
25. Problem solve
26. We can make simple sundial projects out of paper, string or plates
27. Look into what other things the sun affects
28. Dare we mention daylight savings time? It makes the sundial look really out of touch! Learning opportunity here!
29. Stand in our sundial and place markers where our shadows fall one at a time during gardening time and see a
progression.
30. Look at plants that bloom at different times of the day, plants that follow the sun like the sunflower.
31. Use it as a place to gather and hold an outdoor class project related or not to the garden.
Oh the possibilities!
Some basic Casis Sundial facts
- It points True North, the axis of the earth’s rotation. Magnetic north is not perfectly aligned on the axis (just over 4
degrees off in Texas and BTW magnetic north varies up to over 20 degrees in some places on the globe…now you
know!) - The North Star aligns with the earth’s axis. You can find true north many ways. We used a compass with a magnetic
declination device. - Austin’s Latitude at Camp Mabry is 30.32 North and our longitude is 97.77 West. This location is where our sundial is
calibrated from. - Central Standard Time (CST), our time zone, is measured from the 90th meridian. (Each degree takes 4 minutes to
pass during the earth’s rotation.) - It is Analemmatic sundial, which means it uses a moving vertical gnomon to compensate for our latitude.
- A Gnomon (No-Men) is the shadow casting object of a sundial.
- Our sundial measures approximately 22 x 15 feet in its central ellipse and built out of native Texas limestone.
- It tells accurate solar time, which will differ slightly to moderately from our watch time throughout the year. The sundial’
s time is a more accurate measure of our actual local time. - The actual date and time markers will be inset permanently over the next few months.
- The Casis Sundial will display the equation of time and other basic information around its perimeter when completed.
- It was a gift from the 2008 fifth grade class.
It is an amazing teaching tool and an enjoyable space with a “bright” future at Casis.
OH, and one last thing…
“Time zones did not become necessary in the United States until trains made it possible to travel hundreds of miles in a day.
Until the 1860s, almost 150 years ago, most cities relied upon their own local “sun” time, but this time changed by approximately
one minute for every 12 miles traveled east or west. The problem of keeping track of over 300 local times was overcome by
establishing railroad time zones. Until 1883 most railway companies relied on some 100 different, but consistent, time zones.
That year, the United States was divided into four time zones roughly centered on the 75th, 90th, 105th, and 120th meridians.
At noon, on November 18, 1883, telegraph lines transmitted GMT time to major cities where authorities adjusted their clocks to
their zone's proper time.
On November 1, 1884, the International Meridian Conference in Washington, D. C., applied the same procedure to zones all
around the world. The 24 standard meridians, every 15 east and west of 0 at Greenwich, England, were designated the centers
of the zones. The international dateline was drawn to generally follow the 180 meridian in the Pacific Ocean. Because some
countries, islands and states do not want to be divided into several zones, the zones' boundaries tend to wander considerably
from straight north-south lines.”
Source: National Institute of Standards and Technology Physics Laboratory