# Lab 12 Keplers Laws for Asteroid Toro (1).pdf - MANDATORY...

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KEPLER’S THREE LAWS Page 1 of 5 CSULA Astronomy 1520 Lab 1 2 KEPLER’S THREE LAWS FOR THE ORBIT OF THE ASTEROID TORO OBJECTIVE: To introduce the way orbital information is described and to study Kepler’s three laws of orbital motion as applied to the asteroid named Toro. INTRODUCTION: The motion of any orbiter of the Sun is described by Kepler’s three laws of orbital motion. Before stating these laws, we first introduce some of the terms and ideas that the laws involve. An ellipse is an oval loop that has two points called focal points (or foci ) such that if one draws two lines from any point on the circumference of the ellipse to the two foci, the sum of the lengths of the two lines is the same no matter which point on the ellipse is chosen. The ellipse has one axis that is longer than any other axis. This longest axis, which includes both focal points, is called the major axis . Half of the major axis is called the semi-major axis . The length of the semi-major axis is denoted by the letter ' a '. Therefore, the length of the major axis is 2a . Note that by this definition a circle is a special type of ellipse for which the focal points coincide at the center, and the semi-major axis ' a ' is the radius. The ratio of the distance between the foci and the length of the major axis is known as eccentricity ; a circle has an eccentricity of zero. Your lab instructor will demonstrate for you these properties of the ellipse. The length of the semi-major axis of Earth’s orbit around the Sun is defined as one astronomical unit . This is abbreviated as AU , and 1 AU = 93 million miles = 150 million kilometers.