Study GuideAstronomy–The Solar System1. IntroducƟon to the Solar System1.1What Is the Solar System?Thesolar systemis made up of theSun,nine planets, about60 moons, and many smaller objects.These smaller objects includeasteroids, meteoroids, comets, dust, and gas.Even though planets look big in pictures,all of these objects are very small compared to the hugedistances between them. Space is mostly empty!1.2A Helpful Way to Imagine the Solar SystemTo understand just how spread out the solar system is, let’s imagine ascale model.Picture a10-kilometer-long hiking trail.Along this trail, we place models of the Sun and planets at the correct distances from each other.On this scale:•TheSunis only2.3 meters in diameter(about7.6 feet).•Theplanetsare tiny and placedhundreds or thousands of meters apart.•This shows howfar apartthe planets really are, even though textbooks often draw themclose together.1.3Understanding the Scale Model TableThe table above shows three important things for each object in the solar system:1.Position along the trail2.This tells you how far each planet would be from the Sun on the 10-km trail.3.Diameter of the model sphere4.This shows how big each planet would be in the scale model.5.Comment6.This compares each planet’s size to something familiar, like amarble,baseball, orsoccerball, to make it easier to imagine.Preview Mode
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