We look at the models that calculate the positions of planets, focusing on the historical models. When Ptolemy's Earth-centered model, Copernicus' heliocentric model, and Tycho Brahe's geo-heliocentric model were expressed in vector format, they were all the same. Therefore, all three models are sufficiently good enough to calculate the positions of the planets. However, if we look closely at the models, we will see that either the epicycle or the earth-centered solar orbits used circular orbits, while the average Saturn's orbit or the heliocentric Saturn orbit used the eccentric circle for Copernicus, the equant circle for Ptolemy, and the deferent including 2-epicycles for Tycho Brahe. Currently, the planet's position is determined using the heliocentric elliptical orbits, but it can also be accurately traced using the Almagest type geocentric elliptical orbit and the elliptical epicycle.

ABSTRACT
1. 들어가며
2. 태양 중심 모형과 지구 중심 모형
3. 코페르니쿠스 모델
    3.1. 황경 구하기
    3.2. 황위 구하기
4. 프톨레마이오스 모델
    4.1. 황경 구하기
    4.2. 황위 구하기
5. 튀코 브라헤 모델
6. 결론
ACKNOWLEDGMENT
REFERENCES
APPENDIX

• 최승언(서울대학교) | SEUNG-URN CHOE (Seoul National University, Seoul 08826, Korea)
• 민병희(한국천문연구원, 과학기술연합대학원대학, 충북대학교) | BYEONG-HEE MIHN (Korea Astronomy and Space Science Institute, Daejeon 34055, Korea, Korea University of Science and Technology, Daejeon 34113, Korea, Chungbuk National University, Cheongju 28644, Korea) Corresponding author