LAB MODULE 3: EARTH SUN RELATIONSHIP
Note: Please refer to the GETTING STARTED lab module to learn tips on how to set
up and maneuver through the Google Earth ( ) component of this lab.
The following is a list of important words and concepts used in this lab module:
Analemma Equation of time Solstice
Aphelion Equinox Sphericity
Axial parallelism Insolation Subsolar point
Axial Tilt International Date Line Sun Angle
Circle of illumination NDVI Sun-fast, Sun-slow
Coordinated Universal Time (UTC) Perihelion Time zones
Daylight saving time Revolution
Declination of Sun Rotation
LAB MODULE LEARNING OBJECTIVES
After successfully completing this lab module, you should be able to:
● Compute differences in time between two location
● Recognize and demonstrate how time zones work
● Differentiate the changes in the circle of illumination over the course of a
● Identify and describe the reasons for the seasons
● Infer vegetation as an indicator for seasonality
● Read and interpret an analemma
● Calculate the Sun’s declination for a given location and date
● Compute the equation of time for a given location
This lab module examines fundamental Earth-Sun relationships. Topics include time
zones, the equation of time, analemma, declination, solstice and equinox, the
reasons for seasons, and the seasonal migration of the subsolar point. While these
topics may seem disparate, you will learn how they are inherently related.
The modules start with four opening topics, or vignettes, found in the
accompanying Google Earth file. These vignettes introduce basic concepts related to
Earth-Sun relationships. Some of the vignettes have animations, videos, or short
articles that will provide another perspective or visual explanation for the topic at
hand. After reading each vignette and associated links, answer the following
questions. Please note that some components of this lab may take a while to
download or open, especially if you have a slow internet connection.
Expand EARTH-SUN RELATIONSHIPS, and then expand the INTRODUCTION
folder. Double click Topic 1: Earth-Sun Relations.
Read Topic 1: Earth-Sun Relations.
Question 1: Looking at the maps, which of the following best showcases the
uneven balance of insolation – and resulting seasonality – on planet Earth?
A. Most of the northern hemisphere is free of ice and snow year round
B. Most of the northern hemisphere is covered in ice and snow year round
C. Most of the northern hemisphere shows ice and snow advancing in the
D. Most of the northern hemisphere shows ice and snow retreating in July
Read Topic 2: Reason for Seasons. (Note: If you are having issues watching
the animation, please check to see if the movie has been downloaded rather than
automatically playing via the webpage)
Question 2: Why does each hemisphere receive the same amount of energy
from the Sun on the March and September equinoxes?
E. The subsolar point is aligned with the Tropic of Cancer
F. The subsolar point is aligned with the Tropic of Capricorn
G. The subsolar point is aligned with the Equator
H. The subsolar point is aligned with the North Pole
Read Topic 3: Time Zones.
Question 3: What was the main reason for instituting standard time (time
A. To end confusion in communities using their own solar time
B. To help astrologers forecast urban growth patterns
C. To reaffirm England’s world dominance
D. To validate the Meridian Conference of 1884
Read Topic 4: Human Interactions.
Question 4: Name 3 reasons ancient cultures used stone structures or
modified natural formations regarding Earth-Sun or Earth-Moon relationships.
A. To chart seasons, create calendars, and celebrate birthdays
B. To monitor eclipses, mark deaths, denote holidays
C. To chart seasons, monitor eclipses and create calendars
D. To celebrate birthdays, mark deaths and denote the end of days
Collapse and uncheck the INTRODUCTION folder.
I. Coordinated Universal Time (UTC)
The Earth is divided into 24 time zones, one for each hour of the day. Earth’s 24
time zones are approximately 15° wide – a width calculated from the number of
degrees in a sphere divided by the number of hours in a day (360°/24hr =
15°/hour). Noon (12pm) occurs roughly when the Sun is at its highest point in the
sky each day. For example, noon in New York is three hours before noon in Los
Angeles because there is (approximately) a three hour difference in when the Sun
is at its zenith.
Expand the GLOBAL PERSPECTIVE folder and then expand and select the
Universal Time Coordinated folder.
Time zones are as much a Sun-Earth relationship as they are a human construct
used to standardize time. The Prime Meridian – which signifies 0 degrees latitude
and passes through Greenwich, England – is the starting reference line for time
zonation. Time zones are relative