Based on measured astronomical position data of heavenly objects in the Solar System and other planetary systems in the Universe, all bodies in space seem to move in some kind of elliptical motion with respect to each other. In this book, it is mathematically demonstrated and proven that bodies moving on two different circular orbits in space vector-wise behave as if moving on an elliptical path with respect to each other, and virtually seeing each other at an instantaneously stationary point in space on their relative virtual ecliptic plane. This mathematical revelation has the potential to lead to far reaching discoveries in physics, enabling more insight into forces of nature, with a formulation of a new fundamental model regarding the motions of bodies in the Universe, including the Sun, Planets, and Satellites in the Solar System and elsewhere, as well as at particle and subatomic level. Based on the demonstrated mathematical analysis, the assertion is made that the Sun, the Earth, and the Moon must each be revolving in their individual circular orbits of revolution in space, as they exhibit almost fixed elliptical orbits relative to one another over time. With this assertion, individual orbital parameters of the Sun, the Earth, and the Moon are also calculated based on observed Earth-Sun and Earth-Moon distance data, to an approximation, with an analytical method also developed in this book. The analysis has revealed additional results aligned with observation, supporting our assertion that the Sun, the Earth, and the Moon must actually be revolving in circular orbits, with additional surprising insight into the orbits of these heavenly bodies, which can all be found inside. This book consists of: Four scientific papers detailing the research results of Aslı Pınar Tan on this subject, a fifth scientific paper presenting the overall picture of obtained results, and a sixth scientific paper with an overview of results for readers in Turkish. Here is a short video overview description of the research results of Aslı Pınar Tan published in detail in this book "Everything Is A Circle: A New Model For Orbits Of Bodies In The Universe", to provide an introductory idea for readers and scientific community in general: https: //youtu.be/XdpSZj63IFw . An overview of the most significant research results discovered in this book has been published by Aslı Pınar Tan in the open access Astrophysics preprint paper "Everything Is A Circle: A New Universal Orbital Model" (https: //www.doi.org/10.20944/preprints202104.0663.v1) on MDPI Preprints.org, as well as the Mathematical Physics preprint paper "Distance Between Two Circles In Any Number Of Dimensions Is A Vector Ellipse" (https: //www.doi.org/10.20944/preprints202104.0632.v1) and Economics preprint paper "Four Dimensional Circular Model To Measure Interaction Of Two Economies" (https: //www.doi.org/10.20944/preprints202104.0684.v2) that have been published as extensions to the research revealed in this book.