UNDER CONSTRUCTION
DOES THE SUN RISE IN THE EAST AND SET IN WEST?
Posted by Maj Gen Surjit Singh on Dec 22nd, 2013 in Reflections, Abstractions & Historical
http://amolak.in/web/does-the-sun-rise-in-the-east-and-set-in-west/
At the outset, the question seems weird. Right from our Primary school days, we have been taught to believe that it rises in East. But a closer examination reveals that this is not the whole truth. We discovered this when we were working on the 'Sundial' which we erected in the NDA six years ago.
We also found that for thousands of years before the clock was invented, the Sun was our sole means for telling time and identifying directions. We are now looking towards the Sun for energy, and so it is useful to study a bit of astronomy! I wrote a very brief piece on this subject and it has been posted on our blog.
Surjit
(The article is placed below for convenience)
Does the Sun rise in the East? If the answer is an unqualified yes, then this story would not be worth reading. And if it is in the negative, it fouls with our primary school teaching. Permit me to mention that direction of the Sunrise and the Sunset varies with the latitude and changes with the seasons. The extreme deviations are observed during what is called the Solstice days. This year (2013) the winter solstice was on 21st December. If this issue attracts your attention, get up in the morning and point a compass towards the East. If you are located in or around Delhi, you will observe that the Sunrise will be at an angle 28.8 degrees to the South of East. If you are a late riser, watch the Sunset. Once again you will see the Sun going into the horizon at an angle of about 26.4 degrees South of the West. These inputs, amongst many others have come to me from my old friend, Joseph Thomas.
Azimuth Angles These angles are called azimuth angles. At the Equator, the angle remains nearly constant all through the year. On the rest of the Earth, it swings from South East to North East. Indeed, during the Equinox (21 March and 21 September) it becomes due East. For those interested in this subject, I am giving below, the pictures of how these angles are measured. It is customary to treat due North as zero, and then we count it clockwise. Thus East is 90 degrees, South is 180 and West is 270 degrees, as shown below:
In the Southern Hemisphere, the counting is the opposite: there, South is zero, as given below:
Thomas surfed through the Internet and has sent the following figures related with the Latitude of Delhi, which is approximately 29 degrees North. In addition to the azimuth angles he has also given us ‘the noon angles’ about which we will talk a little later.
Date
Noon Elevation(Deg)
Sunrise(Hrs Local)
Sunrise(Hrs IST)
Azimuth Angle(Sunrise)
Sunset(Hrs Local)
SunsetHrs (IST)
Azimuth Angle(Sunset
Declination(Deg)
Remarks
20 Mar 13
61.00
0600
0622
090.2
1759.5
1821.5
270.1
0.000
Equinox at 1602 hrs
21 Jun 13
84.27
0458
0520
063.2
1849
1911
298.2
+23.437
Solstice at 1000 hrs
23 Sep 13
60.60
0545
0607
091.9
1744
1806
271.7
0.000
Equinox at 0146 hrs
21 Dec 13
36.43
0646
0708
118.8
1654
1716
243.6
-23.437
Winter solstice at 2230 hrs
![]()
You may now choose your own method to determine the East and the West and observe the Sunset or the Sunrise, as you like it. The Golfers will appreciate this phenomenon more, because they see the Sun emerging through the different seasons, and watch it in all its glory. Here is a picture which I took at the Chandigarh Lake a few days back.
Part Two – The Story of Sundials
![]()
In the digital age, the process of telling time during day or night, is a simple process. It is on the cell phones, computers, television sets and there are clocks all around. All this is a recent phenomenon. Just a hundred years ago, very few people had a watch of their own. There were clock towers in prominent places and the Churches, which struck the hour. Go back in the history and you find that these clocks are no more than seven hundred years old. Before that, there was ONLY one method of telling time, and that was by observing the shadow cast by the Sun. Given below is a picture of a typical clock tower. It is in the Golden Temple, Amritsar. And exists even thought no one looks at it to tell time any more.Have you ever wondered how people told time before the invention of the clock? It was through Sundial. They were created in several forms. But in all cases, there is one thing in common. Every Sundial has a surface known as the ‘gnomon’ It is inclined at an angle equal to the latitude of the place where the Sundial is located and it points towards the North. The shadow cast by the ‘gnomon’ on the dial tells the time of the day. The Sundial in the Golden temple has survived till the present day. It is located on bridge which joins the outer walkway (called ‘parkarma’) with the Sanctum Santorum. As one passes over the bridge, it is located on the left side, and is almost half way down the bridge. Given below are a couple of pictures of the instrument.
![]()
![]()
And here is a close up of the Sundial
The above simple Sundial has one disadvantage: at around the noon the resolution is very little, while at sunrise and the sunset, you can tell time with much greater precision. Maharaja Jai Singh of Jaipur improved upon this and created a Large circular sundial at the Jantar Mantar in Jaipur, which was later repeated in Delhi and it continues to exist till this date as a solar observatory.
![]()
To commemorate the Golden Jubilee of our joining the National Defence Academy, Kharakvasla, the XIX Course association erected a Sundial near the Gole Market. A picture of this dial is given below:
Vice Admiral Krishnan was the principal architect of this 25 feet tall monument and you see him walking on the left, with his back facing the camera. Our Pune based friends Sooraj Sriram and Vivek Sapatnekar made valuable contribution in this project. George Poonen who came from the USA had this event covered by having a postage stamp issued by the US postal department. A picture is given below:
While conceptualizing the model and as a memento for this two models were made in Delhi. Pictures of these models are given below. In these models we also added two vertical ‘pins’ which can measure the ‘azimuth’ angle and the ‘noon elevation’ You can see these angles marked on the model. Here are the pictures:
![]()
This model was made of stainless steel, since in the beginning we intended to use it in the final version. However, we noticed that steel shines, and therefore it does not produce sharp shadows. In the other model (made of wood) we used a anodized aluminum, which proved to be a more appropriate material. Notice the angle markings for determining solar angles.
Sundial Time and the Clock Hour An interesting observation we made was that the Sundial reads the solar time. It divides the daylight period into the desired number of fragments. In India, the day was conventionally divided into eight “Pahers” Four during the day and four at night. The word ‘dopaher’ (which coincides with the noon) marks the end of the second ‘paher’ The ‘paher’ was sub-divided into three ‘gharhis’ and the smaller units of time were known in India as ‘pal’ and ‘kshana’ The point to note is that during the summer when the length of the day increases, the paher became longer, and in the winter it became shorter. For a long time there was a debate amongst the intellectual on this issue. Indeed, at the end of the day, the clock hour was accepted as the universal standard, which divides the solar ‘day’ into 24 equal parts regardless![]()
of the season.
![]()
The Noon Angle The importance of the ‘noon angle’ can hardly be over-emphasized. This is the angle which the Sun makes with the horizontal plane at the Noon time. Whenever the noon angle is closer to 90 degrees, the solar radiations have to traverse the smallest distance through our atmosphere, and so we get more light and heat. At Sunset, Sunrise and during the winter, the Sun is at a low angle, and therefore, its radiation gets attenuated. The following pictures show this phenomenon.
This is hot Sun, which we receive in the tropics. The evening Sun looks this:
From Which Direction Does the Sun Rise at the North Pole?![]()
Just shoot this question at a few of your friends. And see them trying to find the answer. Some will, indeed, hit back and say that the Sun does not rise at the North Pole! This is only partially true. The Sun does rise ONCE a year in March and it sets in September. And since the ONLY direction at the North Pole is the South, the Sun rises and sets in the south!
A Tailpiece.
When I was talking about the Sundials to the children of a school, a smart child asked me, “Sir, how ill you tell time with the Sundial at night?” I shot the question back at them. They came out with a number of answers including the use of the shadow of the moon, during the moonlit nights. But the smartest answer was,
“I will ring up my cousin in the USA!!!”
~ Thoughts? ~
N RISE IN THE EAST AND SET IN WEST?
Posted by Maj Gen Surjit Singh on Dec 22nd, 2013 in Reflections, Abstractions & Historical
http://amolak.in/web/does-the-sun-rise-in-the-east-and-set-in-west/
At the outset, the question seems weird. Right from our Primary school days, we have been taught to believe that it rises in East. But a closer examination reveals that this is not the whole truth. We discovered this when we were working on the 'Sundial' which we erected in the NDA six years ago.
We also found that for thousands of years before the clock was invented, the Sun was our sole means for telling time and identifying directions. We are now looking towards the Sun for energy, and so it is useful to study a bit of astronomy! I wrote a very brief piece on this subject and it has been posted on our blog.
Surjit
(The article is placed below for convenience)
![]()
Does the Sun rise in the East?
If the answer is an unqualified yes, then this story would not be worth reading. And if it is in the negative, it fouls with our primary school teaching. Permit me to mention that direction of the Sunrise and the Sunset varies with the latitude and changes with the seasons. The extreme deviations are observed during what is called the Solstice days. This year (2013) the winter solstice was on 21st December. If this issue attracts your attention, get up in the morning and point a compass towards the East. If you are located in or around Delhi, you will observe that the Sunrise will be at an angle 28.8 degrees to the South of East. If you are a late riser, watch the Sunset. Once again you will see the Sun going into the horizon at an angle of about 26.4 degrees South of the West. These inputs, amongst many others have come to me from my old friend, Joseph Thomas.
![]()
Azimuth Angles
These angles are called azimuth angles. At the Equator, the angle remains nearly constant all through the year. On the rest of the Earth, it swings from South East to North East. Indeed, during the Equinox (21 March and 21 September) it becomes due East. For those interested in this subject, I am giving below, the pictures of how these angles are measured. It is customary to treat due North as zero, and then we count it clockwise. Thus East is 90 degrees, South is 180 and West is 270 degrees, as shown below:
![]()
In the Southern Hemisphere, the counting is the opposite: there, South is zero, as given below:
Thomas surfed through the Internet and has sent the following figures related with the Latitude of Delhi, which is approximately 29 degrees North. In addition to the azimuth angles he has also given us ‘the noon angles’ about which we will talk a little later.
Date
Noon Elevation(Deg)
Sunrise(Hrs Local)
Sunrise(Hrs IST)
Azimuth Angle(Sunrise)
Sunset(Hrs Local)
SunsetHrs (IST)
Azimuth Angle(Sunset
Declination(Deg)
Remarks
20 Mar 13
61.00
0600
0622
090.2
1759.5
1821.5
270.1
0.000
Equinox at 1602 hrs
21 Jun 13
84.27
0458
0520
063.2
1849
1911
298.2
+23.437
Solstice at 1000 hrs
23 Sep 13
60.60
0545
0607
091.9
1744
1806
271.7
0.000
Equinox at 0146 hrs
21 Dec 13
36.43
0646
0708
118.8
1654
1716
243.6
-23.437
Winter solstice at 2230 hrs
![]()
You may now choose your own method to determine the East and the West and observe the Sunset or the Sunrise, as you like it. The Golfers will appreciate this phenomenon more, because they see the Sun emerging through the different seasons, and watch it in all its glory. Here is a picture which I took at the Chandigarh Lake a few days back.
Part Two – The Story of Sundials
![]()
In the digital age, the process of telling time during day or night, is a simple process. It is on the cell phones, computers, television sets and there are clocks all around. All this is a recent phenomenon. Just a hundred years ago, very few people had a watch of their own. There were clock towers in prominent places and the Churches, which struck the hour. Go back in the history and you find that these clocks are no more than seven hundred years old. Before that, there was ONLY one method of telling time, and that was by observing the shadow cast by the Sun. Given below is a picture of a typical clock tower. It is in the Golden Temple, Amritsar. And exists even thought no one looks at it to tell time any more.Have you ever wondered how people told time before the invention of the clock? It was through Sundial. They were created in several forms. But in all cases, there is one thing in common. Every Sundial has a surface known as the ‘gnomon’ It is inclined at an angle equal to the latitude of the place where the Sundial is located and it points towards the North. The shadow cast by the ‘gnomon’ on the dial tells the time of the day. The Sundial in the Golden temple has survived till the present day. It is located on bridge which joins the outer walkway (called ‘parkarma’) with the Sanctum Santorum. As one passes over the bridge, it is located on the left side, and is almost half way down the bridge. Given below are a couple of pictures of the instrument.
![]()
![]()
And here is a close up of the Sundial
The above simple Sundial has one disadvantage: at around the noon the resolution is very little, while at sunrise and the sunset, you can tell time with much greater precision. Maharaja Jai Singh of Jaipur improved upon this and created a Large circular sundial at the Jantar Mantar in Jaipur, which was later repeated in Delhi and it continues to exist till this date as a solar observatory.
![]()
To commemorate the Golden Jubilee of our joining the National Defence Academy, Kharakvasla, the XIX Course association erected a Sundial near the Gole Market. A picture of this dial is given below:
Vice Admiral Krishnan was the principal architect of this 25 feet tall monument and you see him walking on the left, with his back facing the camera. Our Pune based friends Sooraj Sriram and Vivek Sapatnekar made valuable contribution in this project. George Poonen who came from the USA had this event covered by having a postage stamp issued by the US postal department. A picture is given below:
While conceptualizing the model and as a memento for this two models were made in Delhi. Pictures of these models are given below. In these models we also added two vertical ‘pins’ which can measure the ‘azimuth’ angle and the ‘noon elevation’ You can see these angles marked on the model. Here are the pictures:
![]()
This model was made of stainless steel, since in the beginning we intended to use it in the final version. However, we noticed that steel shines, and therefore it does not produce sharp shadows. In the other model (made of wood) we used a anodized aluminum, which proved to be a more appropriate material. Notice the angle markings for determining solar angles.
Sundial Time and the Clock Hour
An interesting observation we made was that the Sundial reads the solar time. It divides the daylight period into the desired number of fragments. In India, the day was conventionally divided into eight “Pahers” Four during the day and four at night. The word ‘dopaher’ (which coincides with the noon) marks the end of the second ‘paher’ The ‘paher’ was sub-divided into three ‘gharhis’ and the smaller units of time were known in India as ‘pal’ and ‘kshana’ The point to note is that during the summer when the length of the day increases, the paher became longer, and in the winter it became shorter. For a long time there was a debate amongst the intellectual on this issue. Indeed, at the end of the day, the clock hour was accepted as the universal standard, which divides the solar ‘day’ into 24 equal parts regardless![]()
of the season.
![]()
The Noon Angle
The importance of the ‘noon angle’ can hardly be over-emphasized. This is the angle which the Sun makes with the horizontal plane at the Noon time. Whenever the noon angle is closer to 90 degrees, the solar radiations have to traverse the smallest distance through our atmosphere, and so we get more light and heat. At Sunset, Sunrise and during the winter, the Sun is at a low angle, and therefore, its radiation gets attenuated. The following pictures show this phenomenon.
This is hot Sun, which we receive in the tropics. The evening Sun looks this:
From Which Direction Does the Sun Rise at the North Pole?
![]()
Just shoot this question at a few of your friends. And see them trying to find the answer. Some will, indeed, hit back and say that the Sun does not rise at the North Pole! This is only partially true. The Sun does rise ONCE a year in March and it sets in September. And since the ONLY direction at the North Pole is the South, the Sun rises and sets in the south!
A Tailpiece.
When I was talking about the Sundials to the children of a school, a smart child asked me, “Sir, how ill you tell time with the Sundial at night?” I shot the question back at them. They came out with a number of answers including the use of the shadow of the moon, during the moonlit nights. But the smartest answer was,
“I will ring up my cousin in the USA!!!”
~ Thoughts? ~
DOES THE SUN RISE IN THE EAST AND SET IN WEST?
Posted by Maj Gen Surjit Singh on Dec 22nd, 2013 in Reflections, Abstractions & Historical
http://amolak.in/web/does-the-sun-rise-in-the-east-and-set-in-west/
At the outset, the question seems weird. Right from our Primary school days, we have been taught to believe that it rises in East. But a closer examination reveals that this is not the whole truth. We discovered this when we were working on the 'Sundial' which we erected in the NDA six years ago.
We also found that for thousands of years before the clock was invented, the Sun was our sole means for telling time and identifying directions. We are now looking towards the Sun for energy, and so it is useful to study a bit of astronomy! I wrote a very brief piece on this subject and it has been posted on our blog.
Surjit
(The article is placed below for convenience)
Does the Sun rise in the East? If the answer is an unqualified yes, then this story would not be worth reading. And if it is in the negative, it fouls with our primary school teaching. Permit me to mention that direction of the Sunrise and the Sunset varies with the latitude and changes with the seasons. The extreme deviations are observed during what is called the Solstice days. This year (2013) the winter solstice was on 21st December. If this issue attracts your attention, get up in the morning and point a compass towards the East. If you are located in or around Delhi, you will observe that the Sunrise will be at an angle 28.8 degrees to the South of East. If you are a late riser, watch the Sunset. Once again you will see the Sun going into the horizon at an angle of about 26.4 degrees South of the West. These inputs, amongst many others have come to me from my old friend, Joseph Thomas.
Azimuth Angles These angles are called azimuth angles. At the Equator, the angle remains nearly constant all through the year. On the rest of the Earth, it swings from South East to North East. Indeed, during the Equinox (21 March and 21 September) it becomes due East. For those interested in this subject, I am giving below, the pictures of how these angles are measured. It is customary to treat due North as zero, and then we count it clockwise. Thus East is 90 degrees, South is 180 and West is 270 degrees, as shown below:
In the Southern Hemisphere, the counting is the opposite: there, South is zero, as given below:
Thomas surfed through the Internet and has sent the following figures related with the Latitude of Delhi, which is approximately 29 degrees North. In addition to the azimuth angles he has also given us ‘the noon angles’ about which we will talk a little later.
Date
Noon Elevation(Deg)
Sunrise(Hrs Local)
Sunrise(Hrs IST)
Azimuth Angle(Sunrise)
Sunset(Hrs Local)
SunsetHrs (IST)
Azimuth Angle(Sunset
Declination(Deg)
Remarks
20 Mar 13
61.00
0600
0622
090.2
1759.5
1821.5
270.1
0.000
Equinox at 1602 hrs
21 Jun 13
84.27
0458
0520
063.2
1849
1911
298.2
+23.437
Solstice at 1000 hrs
23 Sep 13
60.60
0545
0607
091.9
1744
1806
271.7
0.000
Equinox at 0146 hrs
21 Dec 13
36.43
0646
0708
118.8
1654
1716
243.6
-23.437
Winter solstice at 2230 hrs
You may now choose your own method to determine the East and the West and observe the Sunset or the Sunrise, as you like it. The Golfers will appreciate this phenomenon more, because they see the Sun emerging through the different seasons, and watch it in all its glory. Here is a picture which I took at the Chandigarh Lake a few days back.
Part Two – The Story of Sundials
In the digital age, the process of telling time during day or night, is a simple process. It is on the cell phones, computers, television sets and there are clocks all around. All this is a recent phenomenon. Just a hundred years ago, very few people had a watch of their own. There were clock towers in prominent places and the Churches, which struck the hour. Go back in the history and you find that these clocks are no more than seven hundred years old. Before that, there was ONLY one method of telling time, and that was by observing the shadow cast by the Sun. Given below is a picture of a typical clock tower. It is in the Golden Temple, Amritsar. And exists even thought no one looks at it to tell time any more.Have you ever wondered how people told time before the invention of the clock? It was through Sundial. They were created in several forms. But in all cases, there is one thing in common. Every Sundial has a surface known as the ‘gnomon’ It is inclined at an angle equal to the latitude of the place where the Sundial is located and it points towards the North. The shadow cast by the ‘gnomon’ on the dial tells the time of the day. The Sundial in the Golden temple has survived till the present day. It is located on bridge which joins the outer walkway (called ‘parkarma’) with the Sanctum Santorum. As one passes over the bridge, it is located on the left side, and is almost half way down the bridge. Given below are a couple of pictures of the instrument. 
And here is a close up of the SundialThe above simple Sundial has one disadvantage: at around the noon the resolution is very little, while at sunrise and the sunset, you can tell time with much greater precision. Maharaja Jai Singh of Jaipur improved upon this and created a Large circular sundial at the Jantar Mantar in Jaipur, which was later repeated in Delhi and it continues to exist till this date as a solar observatory.
Vice Admiral Krishnan was the principal architect of this 25 feet tall monument and you see him walking on the left, with his back facing the camera. Our Pune based friends Sooraj Sriram and Vivek Sapatnekar made valuable contribution in this project. George Poonen who came from the USA had this event covered by having a postage stamp issued by the US postal department. A picture is given below:
While conceptualizing the model and as a memento for this two models were made in Delhi. Pictures of these models are given below. In these models we also added two vertical ‘pins’ which can measure the ‘azimuth’ angle and the ‘noon elevation’ You can see these angles marked on the model. Here are the pictures:
This model was made of stainless steel, since in the beginning we intended to use it in the final version. However, we noticed that steel shines, and therefore it does not produce sharp shadows. In the other model (made of wood) we used a anodized aluminum, which proved to be a more appropriate material. Notice the angle markings for determining solar angles.
Sundial Time and the Clock Hour An interesting observation we made was that the Sundial reads the solar time. It divides the daylight period into the desired number of fragments. In India, the day was conventionally divided into eight “Pahers” Four during the day and four at night. The word ‘dopaher’ (which coincides with the noon) marks the end of the second ‘paher’ The ‘paher’ was sub-divided into three ‘gharhis’ and the smaller units of time were known in India as ‘pal’ and ‘kshana’ The point to note is that during the summer when the length of the day increases, the paher became longer, and in the winter it became shorter. For a long time there was a debate amongst the intellectual on this issue. Indeed, at the end of the day, the clock hour was accepted as the universal standard, which divides the solar ‘day’ into 24 equal parts regardless
This is hot Sun, which we receive in the tropics. The evening Sun looks this:
From Which Direction Does the Sun Rise at the North Pole?
Just shoot this question at a few of your friends. And see them trying to find the answer. Some will, indeed, hit back and say that the Sun does not rise at the North Pole! This is only partially true. The Sun does rise ONCE a year in March and it sets in September. And since the ONLY direction at the North Pole is the South, the Sun rises and sets in the south!A Tailpiece.
When I was talking about the Sundials to the children of a school, a smart child asked me, “Sir, how ill you tell time with the Sundial at night?” I shot the question back at them. They came out with a number of answers including the use of the shadow of the moon, during the moonlit nights. But the smartest answer was,
“I will ring up my cousin in the USA!!!”
~ Thoughts? ~
N RISE IN THE EAST AND SET IN WEST?
Posted by Maj Gen Surjit Singh on Dec 22nd, 2013 in Reflections, Abstractions & Historical
http://amolak.in/web/does-the-sun-rise-in-the-east-and-set-in-west/
At the outset, the question seems weird. Right from our Primary school days, we have been taught to believe that it rises in East. But a closer examination reveals that this is not the whole truth. We discovered this when we were working on the 'Sundial' which we erected in the NDA six years ago.
We also found that for thousands of years before the clock was invented, the Sun was our sole means for telling time and identifying directions. We are now looking towards the Sun for energy, and so it is useful to study a bit of astronomy! I wrote a very brief piece on this subject and it has been posted on our blog.
Surjit
(The article is placed below for convenience)
Does the Sun rise in the East?
If the answer is an unqualified yes, then this story would not be worth reading. And if it is in the negative, it fouls with our primary school teaching. Permit me to mention that direction of the Sunrise and the Sunset varies with the latitude and changes with the seasons. The extreme deviations are observed during what is called the Solstice days. This year (2013) the winter solstice was on 21st December. If this issue attracts your attention, get up in the morning and point a compass towards the East. If you are located in or around Delhi, you will observe that the Sunrise will be at an angle 28.8 degrees to the South of East. If you are a late riser, watch the Sunset. Once again you will see the Sun going into the horizon at an angle of about 26.4 degrees South of the West. These inputs, amongst many others have come to me from my old friend, Joseph Thomas.
Azimuth AnglesThese angles are called azimuth angles. At the Equator, the angle remains nearly constant all through the year. On the rest of the Earth, it swings from South East to North East. Indeed, during the Equinox (21 March and 21 September) it becomes due East. For those interested in this subject, I am giving below, the pictures of how these angles are measured. It is customary to treat due North as zero, and then we count it clockwise. Thus East is 90 degrees, South is 180 and West is 270 degrees, as shown below:
In the Southern Hemisphere, the counting is the opposite: there, South is zero, as given below:
Thomas surfed through the Internet and has sent the following figures related with the Latitude of Delhi, which is approximately 29 degrees North. In addition to the azimuth angles he has also given us ‘the noon angles’ about which we will talk a little later.
Date
Noon Elevation(Deg)
Sunrise(Hrs Local)
Sunrise(Hrs IST)
Azimuth Angle(Sunrise)
Sunset(Hrs Local)
SunsetHrs (IST)
Azimuth Angle(Sunset
Declination(Deg)
Remarks
20 Mar 13
61.00
0600
0622
090.2
1759.5
1821.5
270.1
0.000
Equinox at 1602 hrs
21 Jun 13
84.27
0458
0520
063.2
1849
1911
298.2
+23.437
Solstice at 1000 hrs
23 Sep 13
60.60
0545
0607
091.9
1744
1806
271.7
0.000
Equinox at 0146 hrs
21 Dec 13
36.43
0646
0708
118.8
1654
1716
243.6
-23.437
Winter solstice at 2230 hrs
You may now choose your own method to determine the East and the West and observe the Sunset or the Sunrise, as you like it. The Golfers will appreciate this phenomenon more, because they see the Sun emerging through the different seasons, and watch it in all its glory. Here is a picture which I took at the Chandigarh Lake a few days back.
Part Two – The Story of Sundials
In the digital age, the process of telling time during day or night, is a simple process. It is on the cell phones, computers, television sets and there are clocks all around. All this is a recent phenomenon. Just a hundred years ago, very few people had a watch of their own. There were clock towers in prominent places and the Churches, which struck the hour. Go back in the history and you find that these clocks are no more than seven hundred years old. Before that, there was ONLY one method of telling time, and that was by observing the shadow cast by the Sun. Given below is a picture of a typical clock tower. It is in the Golden Temple, Amritsar. And exists even thought no one looks at it to tell time any more.Have you ever wondered how people told time before the invention of the clock? It was through Sundial. They were created in several forms. But in all cases, there is one thing in common. Every Sundial has a surface known as the ‘gnomon’ It is inclined at an angle equal to the latitude of the place where the Sundial is located and it points towards the North. The shadow cast by the ‘gnomon’ on the dial tells the time of the day. The Sundial in the Golden temple has survived till the present day. It is located on bridge which joins the outer walkway (called ‘parkarma’) with the Sanctum Santorum. As one passes over the bridge, it is located on the left side, and is almost half way down the bridge. Given below are a couple of pictures of the instrument. And here is a close up of the SundialThe above simple Sundial has one disadvantage: at around the noon the resolution is very little, while at sunrise and the sunset, you can tell time with much greater precision. Maharaja Jai Singh of Jaipur improved upon this and created a Large circular sundial at the Jantar Mantar in Jaipur, which was later repeated in Delhi and it continues to exist till this date as a solar observatory.
Vice Admiral Krishnan was the principal architect of this 25 feet tall monument and you see him walking on the left, with his back facing the camera. Our Pune based friends Sooraj Sriram and Vivek Sapatnekar made valuable contribution in this project. George Poonen who came from the USA had this event covered by having a postage stamp issued by the US postal department. A picture is given below:
While conceptualizing the model and as a memento for this two models were made in Delhi. Pictures of these models are given below. In these models we also added two vertical ‘pins’ which can measure the ‘azimuth’ angle and the ‘noon elevation’ You can see these angles marked on the model. Here are the pictures:
This model was made of stainless steel, since in the beginning we intended to use it in the final version. However, we noticed that steel shines, and therefore it does not produce sharp shadows. In the other model (made of wood) we used a anodized aluminum, which proved to be a more appropriate material. Notice the angle markings for determining solar angles.
Sundial Time and the Clock Hour
An interesting observation we made was that the Sundial reads the solar time. It divides the daylight period into the desired number of fragments. In India, the day was conventionally divided into eight “Pahers” Four during the day and four at night. The word ‘dopaher’ (which coincides with the noon) marks the end of the second ‘paher’ The ‘paher’ was sub-divided into three ‘gharhis’ and the smaller units of time were known in India as ‘pal’ and ‘kshana’ The point to note is that during the summer when the length of the day increases, the paher became longer, and in the winter it became shorter. For a long time there was a debate amongst the intellectual on this issue. Indeed, at the end of the day, the clock hour was accepted as the universal standard, which divides the solar ‘day’ into 24 equal parts regardless
The importance of the ‘noon angle’ can hardly be over-emphasized. This is the angle which the Sun makes with the horizontal plane at the Noon time. Whenever the noon angle is closer to 90 degrees, the solar radiations have to traverse the smallest distance through our atmosphere, and so we get more light and heat. At Sunset, Sunrise and during the winter, the Sun is at a low angle, and therefore, its radiation gets attenuated. The following pictures show this phenomenon.
This is hot Sun, which we receive in the tropics. The evening Sun looks this:
From Which Direction Does the Sun Rise at the North Pole?
Just shoot this question at a few of your friends. And see them trying to find the answer. Some will, indeed, hit back and say that the Sun does not rise at the North Pole! This is only partially true. The Sun does rise ONCE a year in March and it sets in September. And since the ONLY direction at the North Pole is the South, the Sun rises and sets in the south!A Tailpiece.
When I was talking about the Sundials to the children of a school, a smart child asked me, “Sir, how ill you tell time with the Sundial at night?” I shot the question back at them. They came out with a number of answers including the use of the shadow of the moon, during the moonlit nights. But the smartest answer was,
“I will ring up my cousin in the USA!!!”
~ Thoughts? ~
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