Lesson 1 Lab - Solar system PHYS1404 BreanaMattox

Name: Lesson 1 Lab - Basic Coordinates & Seasons 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: (2 points) 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. 58.2 º W 52.0 º S North Pacific Ocean 157.5º W 21.2º N London, United Kingdom Prime Meridian 51.8º N Cuba 82.1º W Tropic of Cancer Sao Paulo, Brazil 46.4W 23.7S South Pacific Ocean International Date Line Arctic Circle New Orleans, Louisiana 90º W Meridian 30º N Parallel NAAP – Basic Coordinates & Motions 1/9

Latitude : 77.0365 ° W: 77 remains the same since it is the whole number. .0365 x 60=2.1900 .1900 x 60= 11.4000 The Latitude of 77.0365° is: 77° 2’ 11” in sexagesimal form. Longitude: 38.897° N : 38 remains the same since it is the whole number. .892x60=53.820 .820x60=49.200 The Longitude of 38.897° N is: 38° 53’ 49” in sexagesimal form. Question 2: (2 points) Determine which of the 50 states defines the farthest extent of the United States in each of the 4 map directions. Direction State North Alaska South Hawaii East (there are two ways of thinking about this) Alaska West Alaska Question 3: (2 points) 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.)  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 NAAP – Basic Coordinates & Motions 2/9

Question 7: (2 points) 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. Question 8: (1 points) Which direction is east on the flat sky map? Relate this to a coordinate of the celestial equatorial system. Both top and bottom flat border lines, to the right of both top and bottom 0h marks is East on the flat sky map Question 9: (2 points) Complete the following table of positions on the ecliptic. Ecliptic Location Approximate Date Right Ascension Declination Vernal Equinox March 21 0.0h 0.1 ° Summer Solstice June 21 6.0h 23.4 ° Autumnal Equinox September 21 12.0h -0.0 ° Winter Solstice December 21 18.0h -23.2 ° Question 10: (2 points) 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. On the flat sky map, the ecliptic looks like a wave. Its average range, north and south, shows approximately, if not exact, same declination values. Its positive and negative “dips” in its’ wave is around positive & negative 23 °. Seasons and the Ecliptic Work through the introductory material on the page entitled Orbits and Light .  Open the Seasons and Ecliptic Simulator . NAAP – Basic Coordinates & Motions 4/9 RA 5.9H DEC 7.2 ° RA 5.2h DEC -8.1 °

 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.  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 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.

 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: (2 points)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 ° 15.8° S 74.0° N March 21 0.0h -0.0° 0.0° N 90° N & 90° S May 5 2.9 h +16.5° 16.5° N 73.5° S June 21 6.1h +23.4° 23.4° N 66.6° S August 5 9.2h +16.3° 16.3° N 73.7° S September 21 12.1h -0.7° 0.7° S 89.3° N November 5 14.9h -16.5° 16.5° S 73.5° N December 21 18.1h -23.4° 23.4° S 66.6° N Question 12: (2 points) 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. One apparent general rule is that whatever the declination value is, that will also be the most direct sun ray value, Except the sun ray value will be of the opposite pole, with the same number. Another rule that seems obvious is that the most direct and angle of incidence rays should equal to 90 if added together. Question 13: (1 points) 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 subsolar point appears to always stay between the tropics all year round. It is always being hit with direct sunlight. _____ NAAP – Basic Coordinates & Motions 7/9

Question 14: (1 points) 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. The data table shows that the Artic is always in large angles of incidence and never in the most direct. Question 15: (2 points) 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 The noon sun’s angular height above the horizon ranges from 66.3° on the vernal equinox, to 43.1° on the summer solstice, to 66.1° on the autumnal equinox, and then to 90° on the winter solstice. This area on the tropic of cancer begins to have direct sunlight around April which subsides in September. The remaining months fall into larger angles of incidence rays, therefore not as hot as the aforementioned months. 41° N The noon sun’s angular height above the horizon ranges from 48.8° on the vernal equinox, to 25.6° on the summer solstice, to 48.8° on the autumnal equinox, and back to 72.4° on the winter solstice. From the simulator, I can see this area is hardly ever in direct sunlight. About 3 months out of the year are the sun rays more intense compared to the rest of the year. Even out of these 3 months, the sun is never directly overhead. 66.5° N The noon sun’s angular height above the horizon ranges from 24.3° on the vernal equinox, to 1.1° on the summer solstice, to 24.5° on the autumnal equinox, and then to 47.9° on the winter solstice. Compared to those variations in sunlight above, this coordinate has the very least amount direct light, if any light at all. Around December, the sun rays are barely existent. This would explain for the freezing weather in the artic circle. NAAP – Basic Coordinates & Motions 8/9