_TrackingMotionsWorksheet.docx

Tracking Motions Worksheet These lab activities have evolved over many years of use in Clemson University’s Department of Physics and Astronomy general astronomy laboratory. Contributors include, in chronological order, Tom Collins, Mark Leising, Neil Miller, Peter Milne, Grant Williams, Donna Mullenax, Jessica Crist, Keith Davis, Amber Porter, Steven Bromley, and David Connick. Please direct all questions, complaints, and corrections to David Connick (dconnic@clemson.edu) who is responsible for all errors and omissions. Student Name: ____Carson Davis_______ Section: _1030__ The Sun's Yearly Motion Table 1. Month Constellation Rises (am) (Hour:minute) Sets (pm) (Hour:minute) Daylight Length (hours) Altitude (above horizon) (degrees Minutes) January Star in Sagittarius 07:39:03 AM 05:35:40 PM 9.944 hours +32º 52' 49.4" February Star in Capricornus 07:25:25 AM 06:05:49 PM 10.673 hours +39º 44' 14.2" March Star in Aquarius 06:53:56 AM 06:31:39 PM 11.629 hours +49º 44' 46.0" April Star in Pisces 07:11:27 AM 07:56:31 PM 12.751 hours +58º 20' 18.3" May Star in Aries 06:36:02 AM 08:20:25 PM 13.74 hours +67º 48' 23.2 June Star in Taurus 06:18:14 AM 08:42:12 PM 14.399 hours +72º 13' 36.1" July Star in Gemini 06:24:22 AM 08:47:50 PM 14.391 hours +71º 10' 58.0" August Star in Cancer 06:45:14 AM 08:28:48 PM 13.726 hours +66º 27' 17.8" September Star in Leo 07:07:58 AM 07:50:47 PM 12.714 hours +58º 25' 57.3" October Star in Virgo 07:29:51 AM 07:08:27 PM 11.643 hours +48º 22' 25.8" November Star in Libra 06:56:35 AM 05:32:59 PM 10.607 hours +39º 05' 09.4"

December Star in Ophiuchus 07:24:26 AM 05:20:17 PM 9.931 hours +32º 46' 00.3" 1. What month is the Sun's altitude a maximum? ____June_________ 2. What month is the Sun's altitude a minimum? ______December_______ 3. In which month is the length of the day the shortest? ____December__________ 4. In which month is the length of the day the longest? ______June_________ 5. Describe the relationship between the altitude and the length of the day. The month with the sun’s maximum altitude also has the longest days and the month with the minimum altitude has the shortest days. This means that they are directly related. 6. During the longest day of the year, what is the distance from the Earth to the Sun in AU? (You will need to set the date based on your table and look at the info panel for the Sun) __1.014722 AU___ 7. During the shortest day of the year, what is the distance from the Earth to the Sun in AU? (You will need to set the date based on your table and look at the info panel for the Sun) ___ 0.985281 AU___ 8. During lunch, you overhear a group of friends claiming that the cold weather in winter is due to the Earth being furthest from the Sun in its orbit. From your data above, is this claim true? Explain. This is absolutely not true. During the winter (December) the Sun is 0.985281 AU from the Earth. This is closer than the 1.014722 AU that the Earth is from the Sun during the Summer (June). Therefore, the cold and warm weather has nothing to do with the closeness of the Earth and the Sun. 9. What is the true cause of the Seasons? (Use the information in your table and your knowledge from ASTR1010, you should mention the sun’s altitude in your answer) The true cause of the seasons is the Earth's tilt on its axis. This relates to the sun’s altitude because the sun’s altitude is higher in the summer months and lower in the winter. 10. Does the Sun spend an equal amount of time in every Zodiacal constellation? Why or why not? (Give examples) (Look at the path of the sun through the constellations, remember the sun moves along the ecliptic at a constant rate.) The sun does not spend an equal amount of time in each Zodiacal constellation. Some constellations are larger than others.

Return to the instruction document to set up the next simulation before answering the next set of questions. Orbits and retrograde motion 15. Watch Mercury’s movement relative to the grid lines carefully (You can click on Mercury center on it to better see its motion relative to the grid lines), during what time period does Mercury appear to move backwards (to the west)? (This is retrograde motion) Retrograde from Mercury happens around the middle of June. 16. Now search for and center on the Moon. Does the Moon travel precisely along the ecliptic (always touch the ecliptic line)? Explain its motion relative to the ecliptic line. The moon doesn’t travel precisely along it (it doesn’t touch it exactly). It moves right next to it. On March 23rd 2020 the moon is close to the sun and a grid line. Set the time and date to see this in Starry Night. Search for and lock on the Sun then prepare to step time forward and answer the next questions. 17. How long does it take for the moon to return to the same grid line? (this is called the sidereal period) It returned on April 20th so it took 28 days. 18. How long does it take for the moon to get close to the sun again? (this is called the synodic period) It takes 30 days to get close to the sun again. 19. What is the difference in time for the moon to return to the same grid line (background stars) to the time it takes to return close to the sun? There is a two day difference. 20. When viewed from above the north pole, which direction does the Earth orbit the sun, and which direction does the moon orbit the earth? (think back to ASTR1010) The earth orbits the sun counterclockwise and the moon orbits the earth counterclockwise.

21. Do your best to explain the connection between the orbit directions as viewed from above and how we see the sun and moon move in the sky relative to the background stars (grid lines) from the surface of the Earth. The earth is moving west to east. The stars should be moving west to east seeing how we view them.