Conclusion
After completing this sunset laboratory exercise, I noticed several things about
the sunset times and positions. The sunset time and position definitely changes
from day to day even though the change is not always immediately obvious.
The changes in position and time are caused by the Earth's motion around the Sun.
As the Earth follows its almost circular orbit about the Sun, the Sun appears to
move with respect to the horizon. According to my observations, the change was not
constant from day to day. Over a three day span, the Sun set four minutes later.
Then over a five day span, the Sun set one minute later. The reason this change is
inconstant is because the Earth's orbit is an ellipse, even though it is almost a
circle, the tiny eccentricity still makes a difference. By Kepler's Second Law of
Planetary Motion then, the speed at which the Earth orbits the Sun changes at
different points in its orbit. When it is closer to the Sun, it moves faster.
When it is farther from the Sun, it moves slower. During the summer, in the Northern
Hemisphere, Earth is at a point in its orbit where it is farther from the sun.
The change in position and time should be changing slower now than in the winter.
Unfortunately, I have not observed the sunset during winter so I cannot confirm this
guess. I believe that the amound of change is constant all over the world. The
reason being that we are all on the same planet, rotating around the Sun at the same
speed. The sunset time and position will vary from place to place, but the day to
day change will remain constant. I felt that the color of the sunset was more
yellow on hazy and cloudy days. I think the reason for this is that on hazy and
cloudy days, there is more stuff in the air. For example: water molecules. So
when the sunlight passes through the atmosphere, it is refracted differently than
when the air is clear. This results in a slightly different wavelength and therefore
a difference in color (not a very large one.) On June 21, the summer solstice,
the sun set the farthest north in comparison to the observations before and after.
It also set later than in all the observations before and after. The reason for
this is because, on the summer solstice, Earth is at the point in its orbit where
the Northern hemisphere is tilted directly toward the Sun. This results in the
Sun staying above the horizon longer and the sunset being as far north as it is. |
