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ELIPTICAL ORBIT

1.1 INTRODUCTION

By definition, Elliptical Orbitis an orbit that traces out an ellipse as the orbiter rotates aroundanother body (which is located at the focus). Animation shows elliptical orbits with different

eccentricities it also shows how the Sun is at the math behind elliptical orbits. You may think thatmost objects in space that orbit something else move in circles but that isnt the case. Although

some objects follow circular orbits, most orbits are shaped more like stretched out circles orovals. Mathematicians and Astronomers call this oval shape an ellipse. All of the planets in our

solar system, many satellites and most moons move along elliptical orbits.

1.2 EARTHS ELLIPTICAL ORBIT

TheEarth moves around the Sun in an elliptical orbit. Earths orbit is almost a perfect circle; itseccentricity is only 0.0167! Pluto has the least circular orbit of any of the planets in our solar

system. The Sun isnt quiet at the center of the planets elliptical orbit. An ellipse has a point little

bit away from the center called Focus. The Sun is at the focus of the ellipse. Because the Sun is at

the focus, not the center, of the ellipse, the planet moves closer to and furthers away from the Sun

every orbit. The close point in each case is called Perihelion. The far point is called Aphelion

When a satellite traces out an orbit about the center of the earth, its most distant point is called theapogee and its closest point the perigee. The perigee or apogee height of the satellite above the

earth's surface is often given, instead of the perigee or apogee distance from the earth's center. The

ending -gee refers to orbits about the earth; perihelion and aphelion refer to orbits about the sun; the

ending -astron is used for orbits about a star; and the ending -apsis is used when the central body is

not specified. The so-called line of apsides is a straight line connecting the periapts and the

aphasias.

1.3 ELLIPTICAL ORBITS

When one is in orbit around another object, the orbit is usually an elliptical orbit. For example, allof the planets in our Solar System move around the Sun in elliptical orbits. An ellipse is a shape

that can be thought of as stretched out circle or oval. An ellipse can be very long and thin, or it

can be quite round-almost like a circle. Whenan object is in an elliptical orbit around another larger(more massive) object, the larger object is not at the center of the ellipse.When an object is in an elliptical orbit around larger (more massive) object, the larger mass is notat the center of the ellipse. Objects moving in elliptical orbits move fastest when they are closest to

the central body, and most slowly when they are furthest from the central body. Johannes Kepler,

a German astronomer who lived in the early 17th

century, discovered some important laws about

orbits. Keplers First Law of Planetary Motion states that planets move in elliptical orbits. His

Second Law explains how planets move faster when they are close to the Sun (near perihelion) than

when they are far away (near aphelion).

Historicallythe apparent motions of the planets were first understood in terms of epicycles, whichare the sums of numerous circular motions. This predicted the path of the planets quite well, untilJohannes Kepler was able to show that the motion of planets were in fact elliptical motions. Sir

Isaac Newton was able to prove that this was equivalent to an inverse square law, instantaneously

propagating force he called gravitation. In Physics, an orbit is the gravitationally curved path of one

object around a point or another body, for example the gravitational orbit of a planet around a star.

Aplanet has a circular orbit, with the exception of Pluto. A comet has a large but elliptical orbit.

An asteroid has no orbit unless it becomes a moon. A meteor has no orbit. It usually flies in astraight line either burning up in the atmosphere or impacting on a planets surface.

BY: NABEEL BALA ZAKARIthenobleperson@yahoo.com; (+2347028525227, +23480322196 26.)