Building a Scale Model of the Solar System Earth & Sky

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Rosalyn Banks
7 years ago
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1 Building a Scale Model of the Solar System Earth & Sky Name: Introduction Outer space is surprisingly vast and empty. The stars you see in the night sky often burn as bright, or brighter, than the Sun, but the immense distance that the light must travel to reach us helps to dim and shrink the objects to a reasonably small size, distorting our understanding of the distances in space. Furthermore, while light travels extremely fast, nearly 300,000 km/s, light from the nearest stars still takes over 3 years to get to Earth, implying an extremely large amount of empty space. In this lab, you will calculate and design a model solar system and relate it to a map of the RPI campus. Pre-test 1. How far do you think the Moon is from Earth? How much farther do you think the Sun is from the Earth? The nearest star? 2. How many stars do you think are within 10 light years of Earth? 3. How many times farther do you think the nearest galaxy is, compared to the Sun? 1

2 Making a Model In order to build a scale model, we must first pick a base object. In this lab, we will assume that the Sun is only 8 cm in radius, about the size of a standard CD rotated about an axis through the edges and center. From this size and the size of the Sun itself, you can calculate a scale, and then deduce the relative sizes of the other objects in the solar system. You will then use the scale to determine the relative distances of the planets from the Sun, and, ultimately, the distances of nearby stars and galaxies in your scale. Creating a Scale 1. If the radius of the Sun is km, what is the scale of this model? (Remember, the radius of our model Sun is 8cm) 1: 2

3 Calculating Scaled Sizes of Planetary Objects 2. Calculate the scaled sizes of the planets according to this scale, and compare them to the sizes of the following everyday things. Object Average Diameter (mm) CD 80 Finger 20 Peanut 10 Red Ant 5 Rice 3 Mustard Seed 1 Amoeba 0.5 Average Pixel 0.2 Human Hair 0.08 Planetary Body Equatorial Diameter (km) Scaled Diameter Comparable Object Mercury 4878 Venus Earth Earth s Moon 3476 Mars 6792 Ceres Jupiter Saturn Uranus Neptune Pluto Eris Sedna Ceres, a dwarf planet, is the largest asteroid in the asteroid belt between Mars and Jupiter 2 Pluto and Eris are considered dwarf planets, and are the two largest of the Kuiper Belt objects discovered as of Sedna is the 5th-largest trans-neptunian object discovered as of 2007, and the only one of these 5 with an aphelion of more than 500AU. 3

4 Calculating Scaled Distances from the Sun 3. Now, calculate the distances from the Sun of the planets in this scale, and draw a rough estimate of where the planets are located on the RPI map provided in Figure 1. Don t forget to mark where your Sun is! One astronomical unit (AU) is about km. You might not be able to plot the locations of all of these objects. Don t worry if you can t. Planetary Body Average Distance from the Sun (AU) Scaled Distance Mercury Venus Earth Mars Ceres Jupiter Saturn Uranus Neptune Pluto Eris Sedna (Perihelion) Sedna (Aphelion) Here are the nearby stars within 10 light years of Earth. Does the number surprise you? What are their distances in this scale? Plot them (roughly) on the map provided in Figure 2. Can you plot Sedna s aphelion on this map? Remember that a light year is km. Star Distance from the Sun (light years) Scaled Distance Alpha Centauri Barnard s Star Wolf Lalande Sirius Luyten Ross

5 5. The Andromeda galaxy is 2.5 million light years away. In this scale, how far away is it? Post-test 1. As you found above, Earth s Moon is so much smaller than the Sun. Why, then, does it seem almost as large as the Sun in the sky? How much closer do to Earth do you think the Moon is than the Sun? 2. Given that even the fastest trip from Earth to Mars takes 6 months, and the New Horizons mission to Pluto will take nearly 10 years to reach Pluto, how long do you think it would take to reach the nearest star (Alpha Centauri)? Do you think interstellar travel is possible with existing technologies? Why or why not? 3. The nearest exoplanet, or planet outside our Solar System, is 10.5 light years away. Do you think it would be feasible to explore the planet within your lifetime? Why or why not? 5

6 Figure 1: RPI Campus Aerial Photograph 6

7 Figure 2: Equidistant Azumuthal Projection of the World centered on Troy, NY 7

Planets and Dwarf Planets by Shauna Hutton

Planets and Dwarf Planets by Shauna Hutton Name: Wow! Technology has improved so well in the last several years that we keep finding more and more objects in our solar system! Because of this, scientists have had to come up with new categories