PHYS133 Lab 2 Goals: To get an idea of the scale of the solar system with the sizes of the planets. To be able to correctly change from real distances to scale distances. What You Turn In: The tables, answers to questions and completed maps found in the lab (or larger maps provided by your instructor). Background Reading: Background reading for this lab can be found in your text book (specifically, Chapters 1 3 and section 6.1) and the notes for the course. Equipment provided by the lab: Computer with Internet Connection Rulers Protractor Compass Ledger size maps of UD s Newark Campus Equipment provided by the student: Pen Calculator Background: The scale model of the solar system was installed on the University of Delaware s main campus through a grant from the Annie Jump Cannon fund and the National Science Foundation. Although the years have weathered the markers, the name of each planet is easy to read on each marker. The eight planet markers (and on dwarf planet marker) are placed at an appropriate distance from the Sun marker. The Sun marker is located near the base of the front steps to the Old Main building. Each marker states where the next marker in the scale system is located. This may be difficult to read, so the table and image on the next page provides approximate locations. The linear sizes are to scale. The large round part of the maker represents the size of the sun. In reality, the sun is 1,390,000 km in diameter. This is about 109 times the diameter of the Earth. As you travel the scale solar system, look to see if you can see any of the other markers. You should note the size of each planet and how visible it would be to you noting its diameter. You will need to accurately locate the sun and the planets known to the ancients on your maps prior to attending lab. UDel Physics 1 of 7 Fall 2018
Where the Markers Are: The Sun the steps of Old College. Mercury front side of Recitation Hall. Venus back side of Recitation Hall. Earth east of Willard Hall on the walk on the South side of McDowell. Mars South side of Main Street near Brown Hall. Jupiter front of Sharp Lab. Saturn Mall side of the Morris Library on near the steps. Uranus North side of Courtney Street between Manuel and Haines Streets (near a telephone). Neptune in the Botanical Garden near Worrilow Hall. Pluto the prototypical Ice Dwarf Planet, is in front of the Rust Ice Arena. Note we are going to take our view as looking down from above the North Pole of the sun. All the planets travel counter-clockwise in their orbits. UDel Physics 2 of 7 Fall 2018
Before you begin, make sure you read the entire lab including the description of what will be due after the lab is completed! Experimental Procedure: 1. On Map 1, plot the Sun marker and markers for Mecury, Venus, Earth and Mars. 2. On Map 2, plot the Sun marker and markers for Mars, Jupiter and Saturn. 3. Using a compass draw a circular orbit for each planet, centered on the Sun. 4. Now, using the information given in Table 1, if the Sun and Earth markers denote where they would be today, plot the positions of each of the other planets for today as given. a. Draw a light reference line from the Earth to the Sun. b. Centered on the Earth, measure the appropriate angle to the planet (East is counter-clockwise). c. The planet is where the line intersects the appropriate orbit. Mark it! If it intersects twice (as it may for the inferior planets) use the clue of increasing or decreasing angle size to determine which point the planet is located. USE DIFFERENT symbols for the marker, today and one year from today. Denote which orbit belongs to each plaent. Remember, when looking up at the sky, if you lie on on your back with North being above your head, East is to the left. So we measure East direction as being counter clockwise from the sun with West being clockwise from the sun. 5. Now, knowing how long it takes each planet to go around the sun, plot the position of each planet one year from now. a. Look up online or in your text book the orbital (or revolution) period of each planet. b. Determine how many degrees the planet travels around its orbit in 365 Earth days. This is the Posistion Change in one year. The inferior planets should travel around more than one orbit, the superior planets should travel around less than one orbit. Where is the Earth in One Earth Year? c. Centered on the Sun, measure the appropriate angle the planet has moved. Again, remember the planets orbit in an East (i.e., counter-clockwise) direction. d. Where the line intersects the appropriate orbit is the location of the planet. Mark it! 6. On a line that connects the Earth to the planet s new location (one year from now), find its angle relative to the sun and write it down in Table 1. 7. Fill in the missing data in Table 2 below, by finding the scale. I.e., 1m on campus = how many kilometers in the real solar system? 8. In the lab there are various balls. Determine which is the most accurate for the Earth, Sun and other objects your TA suggests. Write these down at the end. UDel Physics 3 of 7 Fall 2018
Table 1 Planet Locations Planet Mercury Length of Year (in earth years) Elongation (Position as seen from Earth relative to Sun) on September 10, 2018 0.24 10.2º W increasing Position change from September 10, 2018 to September 10, 2019 Position Relative to the Sun on September 10, 2019 Venus 0.61 43.4º E decreasing Mars 1.88 132.4º E Jupiter 11.83 61.2º E Saturn 29.41 105.3º E Table 2 Scale Data for Planet Sizes and Orbits Object Diameter (km) Diameter Distance (km) Distance Scale (cm) from the Sun Scale (m) Sun 1,390,000 58.33 0 Mercury 4,900 58,000,000 Venus 12,200 108,000,000 Earth 12,756 150,000,000 Mars 6,794 227,940,000 Jupiter 142,984 778,330,000 Saturn 120,536 1,429,400,000 Rings 250,000 Uranus 51,118 2.15 2,870,990,000 1,205 Neptune 49,532 2.08 4,504,000,000 1,890 Pluto 2,274 0.10 5,913,000,000 2,481 UDel Physics 4 of 7 Fall 2018
Table 3 Scale Data for Major Moons Object Diameter (km) Diameter Distance (km) Distance Scale from planet Scale (cm) (cm) Moon (Earth) Phobos (Mars) Deimos (Mars) Io Europa Ganymede Callisto Titan (Saturn) 3,476.00 384,400 22.20 9,378 12.60 23,459 3,630.00 422,000 3,138.00 670,900 5,262.00 1,070,000 4,800.00 1,883,000 5,150.00 1,221,830 What is the speed of light on this scale? On your maps, are there any planets that have a maximum elongation (i.e., largest angle they can appear) from the sun? For these planets what are the maximum elongations? What do you notice about the distances between the inner planets to their nearest neighbors vs. outer planets? What is in the space between the planets? UDel Physics 5 of 7 Fall 2018
PHYS133 Lab 2 Map 1 UDel Physics 6 of 7 Fall 2018
PHYS133 Lab 2 Map 2 UDel Physics 7 of 7 Fall 2018