The_incredible_2-inch_Universe_01-09-10

# The_incredible_2-inch_Universe_01-09-10 - The incredible...

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Because we spend most of our time as humans interacting with the world on a scale that is human-sized, things we can touch and see and investigate with our senses, it is easy to miss that we are part of a vast universe with objects both unimaginably large and incredibly small compared to the world of our senses. This short introductory exercise is designed to help you shrink down domains of the astronomical world to a size that will give you a sense of relative proportions and distances. We will explore the realms of earth and moon, sun, solar system, and galaxies by shrinking them in turn down to two inch circles. In order to shrink each of the realms in a way that is consistent we need to use ratios. Ratios are ways of comparing two elements, in this case usually size of an object and distances between objects. Realm of the Earth and Moon We will begin by shrinking the Earth to a two – inch diameter circle, then scaling other objects close to earth to see how they compare. Earth has a diameter of approximately 12756 km. We will use the metric system measurements for all astronomical objects today. Since one inch is 2.54 cm, it would be more consistent with the metric system to think of this a 5 cm universe. However, since the United States still doesn’t use the metric standard, most of us are used to thinking in terms of inches and feet and have a better idea of what an inch is (about the length of your thumb from top joint to tip) than what a cm is. Before you begin to calculate, make a guess! Being able to make estimates will be a valuable skill in this course and in many areas of your life. If the Earth were shrunk to just 2 inches across, what do you think the diameter of the moon would be? How far away from us would it be if the distances were shrunk at the same rate? You should look at values in the table to do NOT calculate before you make your estimate. You will not be graded down for a poor estimate, only for not making one! 1. Estimate of moon’s diameter _________________________ 2. Estimate of moon’s distance_________________________ Now do the math. In this realm 2 inches = 12756 km and the Moon is 3475 km in diameter, so how many inches in diameter would it be in our two inch Earth/Moon system? Size of Earth in 2 inch model

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## This note was uploaded on 02/06/2011 for the course ASTR 114 taught by Professor Staff during the Spring '08 term at George Mason.

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The_incredible_2-inch_Universe_01-09-10 - The incredible...

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