1st Catgeory A Lab Kevin nguyen
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Name: Kevin Nguyen
Basic Coordinates & Seasons – Student Guide There are three main sections to this module: terrestrial coordinates, celestial equatorial
coordinates, and understanding how the ecliptic is related to seasons on the Earth. Each
of these sections has its own simulator(s). The background material necessary to utilize
these tools is contained in each section. Terrestrial Coordinates Work through the explanatory material on units of longitude and latitude
, finding longitude and latitude
, and a bit of history
(optional). •
Open the flat map explorer
. •
Familiarize yourself with the cursor and how it prints out the longitude and
latitude of the active map location. •
Note that you can vary the central meridian of the map (i.e. change its longitude).
Use the “shift map” arrows at the top of the simulator to affect large rapid
changes. Use the shift-click feature of the cursor for finer control. •
Note what information is accessible through the show cities
and show map
features
check boxes. •
Center the cursor on your present location. Click the open Google Maps button to
launch the Google Map tool focused on this location. Experiment until you get a
good feeling for the Google Map’s capabilities and then close this window. (Note
that you must be connected to the Internet to make use of this feature.) Question 1:
Use the flat map explorer to complete the following table. You are
encouraged to try and predict the answers and then use the map’s cursor and other
features to check the accuracy of your estimates. Location Longitude Latitude The center of the island of Madagascar. 47.5º W
19.0º S Hawaii, East of Honolulu
157.5º W 21.2º N Greenwich, England
Prime Meridian 51.8º N Havana, Cuba
82.1º W Tropic of Cancer Sao Paulo, Brazil 46.6º W 23.7º S
Chukchi Sea International Date Line Arctic Circle New Orleans, LA
90º W Meridian 30º N Parallel Question 2:
Determine which of the 50 states defines the farthest extent of the United
States in each of the 4 map directions. NAAP – Basic Coordinates & Motions 1/9
Direction State North Alaska South Texas
East (there are two ways
of thinking about this) Maine
West Hawaii
Question 3:
The exact coordinates of the white house in Washington D.C., are 77.0365º
W and 38.897º N. What are these exact coordinates in sexagesimal notation? Show your
calculation in the box below. (You can use the Google Map tool to check your answer.) Degree: 77 º
Minutes: 2.19’= 0.0365 x 60
Seconds: 0.19 x 60 = 11.4”
Longitude in sexagesimal notation ~ 77º 2,’ 11.4” W.
Degree: 38º
Minutes: 0.897º x 60 = 53.82’
Seconds: 0.82’ x 60 = 49.2”
Latitude in sexagesimal notation ~ 38º 53’ 49.2” N. •
Open the globe explorer. You are encouraged to use the Terrestrial Coordinate
Explorers link which opens both simulators at the same time for the following
two questions. Familiarize yourself with the features noting that they are very
similar to those in the flat map explorer. Question 4:
A) Where is the north pole on the flat map explorer
? What is its shape? 90
º N 0º E. Latitude, Undefined Longitude. I don’t think there is a defined shape because
it’s a point where the planets axis of rotation intersects the surface. Visually there are
black and white bars but nothing else. B) Where is the north pole on the globe explorer
? What is its shape? 90degree N, 0-
degree East. The north pole is set at the top of the globe explorer. The shape is a
circular dot.
C) Your answers to parts A and B should be different. Explain why. NAAP – Basic Coordinates & Motions 2/9
The reason parts A and B are different is because on the globe explorer its representing
depth and almost like a 3D model, a flat map with no depth but a 2D line to move
around.
Question 5:
Compare the relative sizes of Greenland and Australia in the two maps? The
true values of the surface areas for these countries are Greenland (2.2 million km
2
) and
Australia (7.7 million km
2
). Does each map demonstrate these true values? On a flat map explorer, landmasses near the poles are distorted or appear larger than they seem to be. Therefore, Australia has more landmass than Greenland, which is why it appears larger than what it is. Which is why specifically Greenland looks bigger than Australia.
Celestial Equatorial Coordinates Work through the introductory material on the page entitled Celestial Equator,
Declination, Right Ascension
. •
Open either the Flat Sky Map Explorer
or the Sky Map Explorer
. •
Familiarize yourself with the same set of features (cursor movement, shifting the
map, decimal/sexagesimal) that were available on the previous maps. •
Make sure that you understand what each check box does. Question 6:
Where is the star Polaris located on this map? What are its coordinates? It is located on the side close to the North Celestial pole. It’s coordinates are Right
Ascension: 2h 31m 48.7s. Declination is +89 degrees, 15”
Question 7:
Find the constellation of Orion shown in the box below and measure the
right ascension and declination of its brightest stars Betelgeuse and Rigel. Note that
Orion is located on the celestial equator. NAAP – Basic Coordinates & Motions 3/9
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RA DEC
+7degree
RA 5h 14m
32.27s
DEC
-8degree
12’ 5.9”
Question 8:
Which direction is east on the flat sky map? Relate this to a coordinate of the
celestial equatorial system. When looking towards the direction of east, it is the
celestial equator in the right ascension direction. The celestial equator is a created
visualized circle on the celestial sphere above the Earth’s equator.
Question 9:
Complete the following table of positions on the ecliptic. Ecliptic Location Approximate Date Right Ascension Declination Vernal Equinox March 21 0 Hours
0 degrees
Summer Solstice June 21 6 hours
+23.5 degrees
Autumnal Equinox September 21
12 Hours
0 Degrees
Winter Solstice December 21 18 Hours
-23.5 Degrees
Question 10:
Write out a description of the ecliptic on the flat sky map. What does the
shape look like? Describe the ecliptic in terms of its average and range of declination
values.
The Ecliptic is depicted as a curved line on a flat sky map which traces a path of the Sun across the celestial sphere. The shape is a slightly tilted circle, with average declination of +23.5 degrees in the northern hemisphere, -23.5 degrees in the southern hemisphere.
NAAP – Basic Coordinates & Motions 4/9
Seasons and the Ecliptic Work through the introductory material on the page entitled Orbits and Light
. •
Open the
Seasons and Ecliptic Simulator
. •
Note that there are three main panels (left, upper right, and lower right) each of
which have two different views. Controls run along the bottom of the simulation
that affect more than one panel. Click animate and then move through the six
views to get an overview this simulator’s capabilities. We will address each of
these six views separately. •
Experiment with the various methods to advance time in the simulator. You may
click the start animate/stop animation button, drag the yearly time slider, or drag
either the sun or the earth in the left panel to advance time. •
Note that this animation does not illustrate the rotation of the earth. Because the
timescales of rotation and revolution are so different, it isn’t possible to
effectively show both simultaneously. Left Panel – Orbit View
•
Practice clicking and dragging in this panel to change the
perspective. Change the perspective so that you are looking
directly down onto the plane of the Earth’s orbit •
Click labels. Note that you can see how the direct rays of the
sun hit at different latitudes throughout the year. •
Experiment with this view until you can quickly create the two views shown
below. Note that these images explain the shape of the elliptic on the celestial
sphere. In the image on the left (summer solstice) an observer on the Earth sees
the sun above the celestial equator. In the image on the right (winter solstice) an
observer on the Earth sees the sun below the celestial equator. Left Panel – Celestial Sphere
•
This view shows the earth at the center of the celestial
sphere. The celestial equator and the ecliptic with the sun’s
location are shown. Note that you may click on the sun and
drag it and read out its coordinates. NAAP – Basic Coordinates & Motions 5/9
Tip:
Note that if you
click and drag the
Earth,
you
will
change the date and
location rather than
the perspective.
•
Experiment with this view until you can quickly create the image to the right – the
direct rays of the sun hitting the earth on the summer solstice. Upper Right Panel – View from Sun
•
This view shows the earth as seen from the sun. It gives the best view of the
subsolar point – the location on the earth where the direct rays of the sun are
hitting. The noon observer’s location on the Earth is indicated by a red parallel of
latitude which can be dragged to new latitudes (this affects the appearance of the
lower right panel). It is possible for the red parallel to be at an inaccessible
location in this view. •
Create the image shown to the right – an observer at latitude 80°N on the summer
solstice. Upper Right Panel – View from Side
•
This view shows the earth as seen from a location in the
plane of the ecliptic along a line tangent to the Earth’s
orbit. It allows one to easily see the regions of the Earth
that are in daylight and those that are in shadow. •
Dragging the stick figure allows one to very conveniently
change latitude. Dragging the stick figure on top of the
subsolar point effectively puts the observer at the latitude
where the direct rays of the sun are hitting. •
Although rotation is suppressed in this simulation,
keep in mind that the stick figure is on a planet that is
rotating with a period of 24 hours about an axis
connecting the north and south poles. Thus, 12 hours
later it will be on the other side of the earth. •
Set up the simulator for the image at right – the winter solstice for an observer at 80
°
N. Since this observer’s parallel of latitude is located entirely in the shaded
region, this observer will not see the sun on this day. Lower Right Panel – Sunbeam Spread
•
This view shows a “cylinder” of light coming from the sun. It is projected on a grid
to convey the area over which the light is spread. As this light is spread over a
larger area, its intensity decreases. Lower Right Panel – Sunlight Angle
•
This view shows the angle with
which rays of sunlight are
NAAP – Basic Coordinates & Motions 6/9
Tip:
Once the stick figure
is selected you can gain
greater precision over its
motion by
moving the
mouse a distance away
from the figure.
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striking the Earth. It lists the noon sun’s angle with respect to the horizon (its
altitude). •
Verify that when the noon observer is at the latitude where the most direct rays of
the sun are hitting, the sun is directly overhead making an angle of 90
°
with the
ground. •
Verify that when the noon observer is at the latitude where the least direct rays of
the sun are hitting, the sun is on the horizon. Question 11:
The table below contains entries for the coordinates for the sun on the ecliptic as well as the latitude at which the most direct and least direct rays of the sun are hitting. Use the simulation to complete the table. Date RA DEC Latitude of
Most Direct Latitude of Least
Direct Ray February 5 21.3h -15.8
degrees
16.5degree S 90degree N
March 21 23.9h
0.0
degrees
0.0 degree
90degree S
May 5 2.9 h +16.5° 16.5° N 90° S June 21 6.1h
23.4
degrees
23.4degree N
90degree S August 5 9.2h
16.3
degrees
16.5-degree N
90 degree S September 21 12.1h
-0.6
degrees
0.0 degree
90 degree N
November 5 14.9h
-16.6
degrees
16.5-degree S
90degree N
December 21 18.1h
-23.4
degrees
23.4-degree S
90degree N
Question 12:
Using the data in the table above, formulate general rules relating the
declination of the sun to the latitude where the most direct and least direct rays of the sun
are
hitting.
Negative declinations is the meaning when the sun comes to the southern hemisphere while positive ones has more suns in general in the northern hemisphere.
NAAP – Basic Coordinates & Motions 7/9
Question 13:
The region between the Tropic of Cancer and the Tropic of Capricorn is
commonly known as the tropics. Using the sunlight data table from question 11, define
the significance of this region. The sunlights are more exposed around these areas.
Question 14:
Using the sunlight data table from question 11, define the significance of
the region north of the Arctic Circle commonly referred to simply as the Arctic. This is the area that gets no to little sunlight during some seasons.
Question 15:
Use the simulator to complete the table below. For each latitude write a
short paragraph which describes the variations in sunlight (seasons) that are experienced
at this latitude throughout the year. Latitude Description of Yearly Pattern of Sunlight 0° The noon sun’s angular height above the horizon ranges from 90° on the
vernal equinox, to 66.5° on the summer solstice, to 90° on the autumnal
equinox, and back to 66.5° on the winter solstice. Thus, the equator always
receives very direct intense sunlight throughout the year which accounts for
the very high temperatures. 23.5° N During the vernal equinox, the Sun reaches an angular height of 66.5° at noon,
NAAP – Basic Coordinates & Motions 8/9
marking the onset of spring. On the summer solstice, this angle peaks at 90°, representing the highest point in the sky and the longest day of the year. As autumn begins on the autumnal equinox, the Sun's noon angle remains at 66.5°, and during the winter solstice, it descends to 43°, signaling the start of winter. These variations in the Sun's angular height correspond to approximately three months of direct sunlight hitting different latitudes throughout the year. 41° N On the vernal equinox, the Sun reaches an angular height of 49° at noon, signifying the arrival of spring. The summer solstice sees the Sun soaring to 71.9°, marking the peak of daylight and warmth. As autumn approaches during
the autumnal equinox, the noon angle remains at 49°, and during the winter solstice, it descends to 25.5°, bringing cooler temperatures to this latitude. The
lower solar angles on the winter solstice contribute to reduced direct sunlight and cooler conditions.
66.5° N During the vernal equinox, the Sun reaches an angular height of 23.5° at noon, signaling the arrival of spring. As the summer solstice unfolds, the Sun climbs to 47.1°, bringing warmth and extended daylight. However, during the autumnal equinox, the noon angle again measures 23.5°, and by the winter solstice, it drops to 0°, resulting in three months of limited sunlight and colder temperatures in this location for the remainder of the year.
90° N At the vernal equinox, the Sun at noon has an angular height of 0°, marking the transition to spring. On the summer solstice, the Sun ascends to 25.5°, providing a brief period of sunlight and slightly warmer days. Conversely, during the autumnal equinox, the noon angle returns to 0°, and on the winter solstice, it reaches -21.0°, resulting in about half of the year with little to no sunlight and no direct sunlight for the remainder. Consequently, the climate remains consistently cold, with only marginal warmth during the days when sunlight is present.
NAAP – Basic Coordinates & Motions 9/9
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