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Daily motion of the sun --- Part2

Introduction

Path of the daily motion of the sun changes with latitudes.

　Do you think the path of the daily motion of the sun is the same anywhere in the earth?
Does the sun move just like we have observed from Japan on Daily motion of the sun Part1?
Watch the movie of daily motion of the sun that was taken in London with a digital camera with a 180-degree field of vision lens and plot the path on a worksheet or a clear plastic hemisphere.
London is located at Latitude 51°N. It is about 15 degrees higher than Sendai, Japan. Is the path the same all year long at any latitudes?
　Length of day and night changes with seasons. Also, at the Arctic, midnight sun is observed around midsummer. Compare the paths of several seasons from several latitude locations.Think of the difference in length of day and night in different seasons and locations from the results.

The locations of London and Japan

The locations of London and Japan

　London is located at Latitude 51°N. Sendai, Japan is at Latitude 38°N. The earth's axis is tilted at 23.4 degree to it's orbit plane. The angle between ground and sun ray changes depending on not only season or time but also latitude. Let's check how it changes.

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The whole sky camera

Over view image of the Whole Sky Camera	Pattern diagram seen from side

　The Whole Sky Camera system is composed of the digital camera, the fisheye lens, and the a level.
Because the fish-eye lens has 180-degree field of view, Whole sky scenery from the place where the camera was set up can be taken in one photograph by turning the camera with the fish-eye lens to the zenith.

The view through the fisheye lens

A picture taken by normal lens	A picture taken by fisheye lens at the same place

How are the movies made?

　From sunrise to sunset, a whole sky photograph is taken at regular intervals by the Whole Sky Camera system. This image data is downloaded onto a computer, the directions and the images are processed, and coordinates of direction and altitude are added to them using Adobe graphic soft Illustrator. Moreover, each image is edited with the passage of time to make movies by using the software Movie Maker to edit Microsoft-based animations.

More!

Experimental Method

Things to prepare

　The movies of daily motion of the sun, taken at two hour intervals, Worksheet ( You can download them.), PC, Application for seeing movies
※If you have any chance to make a movie of daily motion of the sun at school that contains landscape with which you are familiar, that is the best one.

Let's watch the movie!

Watch the movie and check out the path of the sun. From where to where is it moving?

Record the position of the sun at two hour intervals.

　Next, watch the movie, note the position of the sun at each two hour interval and plot it on your worksheet.
　The left is one of the images in the movie of daily motion of the sun taken at 11:43 a.m. (Culmination) on June 21, 2005 at Sendai Japan (latitude 38 degrees north).A light white circle is the sun. The right diagram is the worksheet with the position of the sun plotted by reading the direction and the altitude of it from the left image.
　In the same way, record the path of the sun over a whole day in your worksheet by watching the image every two hours.

Record the path of the sun in London and Japan.

　Watch another movie taken in London and find out if there are any differences between the locations (latitudes).
　In the same way, read the position of the sun from the images every two hours and record the path of the sun during a day.

Experimental Result

The path of the sun on summer solstice in London and Japan.

　The left picture is the path of the sun, which was taken on July 12, 2005 at University of London Observatory (Latitude 51.61 degrees north, longitude 0.24 degrees east, 81 meters high). The right picture is the path of the sun, which was taken on June 21, 2005 at Miyagi University of Education, Sendai, Japan (Latitude 38 degrees north) Record the path of the sun over a whole day in your worksheet by watching the both movies.

　The left picture is the path of the sun, which was taken on July 12, 2005 at University of London Observatory (Latitude 51.61 degrees north, longitude 0.24 degrees east, 81 meters high). The right picture is the path of the sun, which was taken on June 21, 2005 at Miyagi University of Education, Sendai, Japan (Latitude 38 degrees north) Record the path of the sun over a whole day in your worksheet by watching the both movies

The path of the sun on equinox in London and Japan.

　The left picture is the path of the sun, which was taken on October 10, 2005 at University of London Observatory (Latitude 51.61 degrees north, longitude 0.24 degrees east, 81 meters high). The right picture is the path of the sun, which was taken on March 15, 2005 at Miyagi University of Education, Sendai, Japan (Latitude 38 degrees north) Record the path of the sun over a whole day in your worksheet by watching the both movies.

Let's Compare them.---1

　Compare the paths of the sun that recorded in different seasons in the same place.
Can you find out the differences between them in Culmination altitude, position of sunrise, position of sunset and length of daytime? How different are they?

Let's Compare them.---2

　Compare the paths of the sun that recorded in London and Japan in the same season.
Can you find out the differences between them in Culmination altitude, position of sunrise, position of sunset and length of daytime? How different are they?

Practical Description

　Describe what you understood from the observation.

The path of the sun in London in seasons

• The sun rises in the east and sets in the west reaching its highest point in the south.
• The culmination altitude in summer is higher than winter.
• The position of sunrise and sunset in summer becomes more northern than winter.
• Daytime in summer is longer than winter.

Comparing the path of the sun in London with Japan

• London is located higher latitude than Japan.
• The culmination altitude in London is lower than the one in Japan in the same season.
• The sun rises at about 8:00 a.m. and sets at about 3:00 p.m. in London around winter solstice.
• It doesn't get dark until around 10:00 p.m. in London around summer solstice.

Discussion

　Why do the culmination altitude or length of day change with seasons?
　To find out the answer, imagine the motion of the sun in the Celestial Sphere that shows the position of the earth and the sun from the universe.

Download

Movie of Daily Motion of the Sun taken at University of London Observatory (Latitude 51.61 degrees north, longitude 0.24 degrees east, 81 meters high) / Every hours

Around Summer Solstice　July 12, 2005 sunrise 03:56 culmination 12:05 sunset 20:13

wmv (2.6MB)  mpg (12MB)

Around Autumnal Equinox 　October 10, 2005 sunrise 06:15 culmination 11:46 sunset 17:16

wmv (1.5MB)  mpg (6MB)

Around Winter Solstice　November 18, 2005 sunrise 07:23 culmination 11:44 sunset 16:05

wmv (1.8MB) mpg (4MB)

Worksheet

WORD (160KB)　 PDF (120KB)

Related paper

Space experiments in classrooms-7: Development of movies of solar diurnal motion imaged by solar camera PDF(2.3MB)　Bulletin of Miyagi University of Education Vol.40