Which did Kepler notice First about planetary motion that caused him to propose keplers first law of orbital motion

Answer 1

Johannes Kepler noticed that the data collected by Tycho Brahe on the positions of planets did not fit the traditional circular orbital models that were widely accepted at the time. Instead, Kepler observed that the planets appeared to move in elliptical orbits rather than circular ones. This observation led him to propose his First Law of Planetary Motion, which states that planets move in elliptical orbits with the Sun at one of the foci of the ellipse. This was a significant departure from earlier models, which had assumed circular orbits were the norm.