The Sidewalk Solar System For elementary and middle school level children, this is an activity for making a model of the solar system that is to scale using only chalk and a long stretch of sidewalk. It is fun for the entire class, helps children think in terms of models, and helps them learn about the planets. The Sidewalk Solar System Richard Ignace Smashwords Edition Copyrighted 2010 Richard Ignace Smashwords Edition, License Notes Thank you for downloading this free e-book. It may be reproduced, copied and distributed for non-commercial purposes provided it remains in its complete and original form, and that the author and Smashwords are given full acknowledgement. INSTRUCTIONS The following tables describe how to design a scale model of the planets in the solar system as laid out along a school sidewalk. The idea is to use sidewalk pavement blocks as a "standard" of length. There are two tables. The first is for the eight planets of the solar system. The second, if there is enough sidewalk space, is for the dwarf planets. The first column gives the name of the planet or dwarf planet. The second column gives the distance of the object from the Sun, relative to the Earth's distance. The Earth is about 150 million kilometers, or 93 million miles, from the Sun on average. Astronomers call this one astronomical unit, or "1 AU". So the second column is distance in AUs. To get miles or kilometers, multiply by 93 million or 150 million, respectively. The last three columns are for the counting of sidewalk pavement blocks for where to place and color planets (and possibly dwarf planets). The different columns allow for a different number of available blocks: 50, 75, or 100. Take for example the column that is for 100 blocks. The Sun would go at the front edge of the first block, and Neptune would be placed at the far edge of the 100th block. In this case the other planets would be drawn at the indicated block locations, and with the help of teachers, students will need to estimate fractions of a block. Draw circles at the indicated positions, label them for the Sun, planets, or dwarf planets, and color them with sidewalk chalk. Even if the dwarf planets are not indicated, because of limited space, teachers can use the table for dwarf planets to give children a sense of just how far away most of them are from the Sun. Also, even though Ceres is now a dwarf planet, its former classification as the largest of the asteroids means that its position in Table 2 can be used to mark the asteroid belt. Students could make a number of small dots to represent this belt area. Note that if something falls at an integer number, its location is on the line separating two pavement blocks. An example would be Mercury in column three for a layout with 75 blocks. There Mercury should be drawn at a position of 1.0 blocks. That would be on the line at the end of the 1st block and the beginning of the 2nd. It is worth commenting on the scaled sizes of objects as compared to the distances. For the 50 block plan, the Sun's diameter would be only 1.5% (or 0.015) as large as a single block. If your block happened to measure 1 yard = 36 inches, then to draw the Sun to scale, it would be a circle of just over half an inch diameter (or 1.4 cm, about the size of a marble), and the Earth would be a mere 0.13 mm across (like the tip of a sharp pencil). In the 100 block plan, these would be twice as big. The largest planet Jupiter would be only 0.06 inches in diameter (or 15 mm) for the 50 block plan. Children will naturally draw much larger circles to represent the Sun and planets, but it is worth mentioning that if drawn to scale, objects should be much smaller. Block Counting Plan for Solar System Planets Object Distance (AU) 50 Blocks 75 Blocks 100 Blocks Color Sun 0.0 0.0 0.0 0.0 Bright-yellow Mercury 0.39 0.7 1.0 1.3 Slate-gray Venus 072 1.2 1.8 2.4 Off-white Earth 1.0 1.7 2.5 3.3 Blue-green Mars 1.5 2.5 3.8 5.1 Red Jupiter 5.2 8.7 13.0 17.3 Orange-brown Saturn 9.5 15.9 23.9 31.8 Yellow-white Uranus 19.2 32.0 48.0 64.0 Blue-white Neptune 30.0 50.0 75.0 100.0 Dark-blue LEARNING OBJECTIVES I hope that children enjoy this exercise. Making a scaled sidewalk Solar System will help children learn about: names of the planets and dwarf planets, order of the planets and dwarf planets, scaled models in science, colors associated with planets and dwarf planets, sense of vast distances in space, sense of object sizes as compared to distances. CONTACT INFORMATION Please direct any questions or comments to Professor Richard Ignace at East Tennessee State University, by phone at 423 439-6904, or email at ignace@etsu.edu. Block Counting Plan for Dwarf Planets Object Distance (AU) 50 Blocks 75 Blocks 100 Blocks Color Sun 0.0 0.0 0.0 0.0 Bright-yellow Ceres 2.8 4.6 6.9 9.2 Slate-gray Pluto 39.4 65.7 98.6 131.5 Brown-black Haumea 43.3 72.2 108.3 144.3 White-gray Makemake 45.8 76.3 114.5 152.7 Red-brown Eris 67.7 112.8 169.3 225.7 Green-blue ABOUT THE AUTHOR Richard Ignace is an Associate Professor in the Department of Physics and Astronomy at East Tennessee State University. Known by his nickname of "Rico", he is an astrophysicist with a doctorate in astronomy from the University of Wisconsin and also a Masters in physics. Rico has been teaching astronomy and physics at the university level since 1999 to well over 1,000 students. He has also taught a high school level physics course to a group of homeschoolers and has occasionally taught MCAT physics sessions for the Kaplan program. Rico has two primary occupations. First, married since 1988, Rico's wife, Teresa, and six children, Caleb, Joshua, Joseph, Abigail, Simeon, and Lucas, keep life in a constant state of excitement and motion. Second, Rico is an active researcher of stellar astrophysics, generally in the area of theoretical modeling, but also an observer who makes use of NASA's orbiting telescopes, such as Chandra, Spitzer, and others. His interests lie mainly in trying to understand stellar winds, which are outflows of gas from stellar atmospheres into space, and he has won a number of grants from NASA and the National Science Foundation in support of his research activities. Rico also dabbles in a number of other topics, such as exoplanets, gravitational lensing, and supernovae. Rico has previously published the following: Hardcopy - 2002, Understanding the Universe, by Raman Prinja and Richard Ignace Ebook - 2009, WORDS FIRST: Mastering Unit Conversion, by Richard Ignace