practical 3 sce 3110

7/30/2019 Practical 3 SCE 3110

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Practical 3SCE 3110

The rising of the sun

Introduction:

The average distance from the Sun to the Earth is 1.496 x 1011metres (149 million kilometres or

92.58 million miles).

The minimum distance from the sun to the earth is 146 million km (or 91 million miles), and the

maximum distance from the sun to the earth is 152 million kilometres (or 94.5 million miles. )

The sun is a neighborly 93 million miles away. That is the common average figure. Because of the

earth's elliptical orbit around the sun, the distance changes over the course of a year. We are closest

at perihelion (91 million miles) during northern hemisphere winters, and farthest at aphelion, during

northern hemisphere summers. Light from the sun takes roughly 8 minutes to reach the earth. From

the frame of reference of the photons making the trip, arrival is instantaneous.

93 million miles is the distance from the Earth to the Sun (on average), or 8 minutes, 20 seconds at

the speed of light.

Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Theapparent westward revolution of Sun around the earth after rising out of the horizon is due to the

Earth's eastward rotation, a counter-clockwise revolution when viewed from above the North Pole.

The intense red and orange hues of the sky at sunrise and sunset are mainly caused by scattering of

sunlight by dust particles, soot particles, other solid aerosols, and liquid aerosols in the Earth's

atmosphere.

As one travels farther from the equator, the times of sunrise and sunset change throughout the year.

Even on the equator, sunrise and sunset shift several minutes back and forth through the year, along

with solar noon.

Data:

Date Time Azimuth,o Altitude,o

24 February 2010 0630 259 13

0645 259 9

0700 260 5

25 February 2010 0630 259 13

0645 260 9

0700 260 5

26 February 2010 0630 260 13

0645 260 9

0700 260 3

27 February 2010 0630 260 13

0645 260 9

0700 261 5

28 February 2010 0630 261 13


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0645 261 9

0700 261 5

01 March 2010 0630 261 13

0645 261 9

0700 262 5

02 March 2010 0630 261 13

0645 262 9

0700 262 5

03 March 2010 0630 262 13

0645 262 9

0700 262 5

04 March 2010 0630 262 13

0645 262 9

0700 263 5

05 March 2010 0630 263 13

0645 263 9

0700 263 5

06 March 2010 0630 263 13

0645 264 9

0700 264 5

07 March 2010 0630 263 13

0645 264 9

0700 264 5

08 March 2010 0630 264 13

0645 264 9

0700 264 5

09 March 2010 0630 264 13

0645 264 9

0700 265 5

Data analysis:


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The sun is rise from the East and set to the West.

Because of the elliptical nature of the earths orbit and constant changes in the earths rate of spin

because of the previously mentioned phenomena, the sun, as seen from earth, is moving at a non-

uniform rate. This makes it difficult to use the real position of the sun as a reference for time

keeping. For these purposes, a point which moves at a constant rate around the earth is used instead

of the real position of the sun. This point is called the mean sun and is the basis for mean solar time.

From the data, we can see that, the Sun is rising earlier as the day increases. The data shows a little

different in azimuth increasing everyday.

To find out the position azimuth = 60, elevation = 30, for example, imagine standing at the center ofthe diagram heading to the true north. To find the azimuth angle 60, you must turn 60 degrees to the

right. Now the altitude angle 30 can be located by raising your head 30 degrees from the horizon.

1. Azimuth angle

2. Elevation angle

3. Sun's path today

4. Sun's path on the 21st June

5. Sun's path on the 21st December

6. Sun's path during the equinox

7. Sunrise

8. Sunset

9. Horizon

It can be seen from the diagram (3. "Sun's path today") that the sun rises from the North-East

(azimuth = 60) in Tampere at 05:37. Sunset happens at 21:20 when the sun is in the North-West

(azimuth = 300). On that day the elevation angle is approximately 50 degrees at noon.

Conclusion:

The altitude of the Sun is decrease, while the azimuth of the sun is increase as the Sun set everyday.

This phenomenon due to the annual change in the relative position of the Earths axis in the

relationship to the Sun causes the height of the altitude to vary in the sky.

Data interpretation:

Time Azimuth,o Altitude,o

0630 259 13

0645 259 9

0700 260 5Table 1


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Graph: The movement of the Sun

According to the graph, the Sun is move 4o every 15 minutes. As the azimuth increases, the altitude

is decreases.

The azimuth increases about 1o, while the altitude decrease about 4o.

Based on the data collected, the Sun rise earlier everyday. Thats mean the Sun is at upper position

everyday at the same time.

Sun height declines with latitude as we move away from the Equator. For each degree of latitude

traveled maximum Sun height decreases by the same amount. At equinox, we can also calculate the

noon angle by subtracting the location's latitude from 90.

The Sun goes through a seasonal variation, once a year. In December and January, the Sun is in the

far south of the sky. It rises in the south-east; it spends only a few hours above the horizon (for

northern-hemisphere observers), crossing the sky quite low down; and it sets in the south-west.In June and July, the Sun is in the far north of the sky. It rises in the north-east ; it spends many hours

above the horizon (for northern-hemisphere observers), crossing the sky quite high up; and it sets in

the north-west.

the sun appears to move across the sky it means that the shadows also move. The shadows

References

Book

Michael A. Seeds. (2008). Foundation of Astronomy Tenth Edition. Thomas Higher Education. USA

Internet

http://library.thinkquest.org/29033/begin/earthsunmoon.html

http://sse.jpl.nasa.gov/features/planets/earth/earth.html

http://www.windows.ucar.edu/tour/link=/the_universe/uts/earth3.html

practical 3 sce 3110

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