Statement A is correct. Johannes Kepler formulated his laws of planetary motion in the early 17th century, including the first law stating that planets orbit the Sun in elliptical paths with the Sun at one focus. Statement B is correct. Eratosthenes of Cyrene, a Greek scholar in the 3rd century BC, is famous for making the first relatively accurate calculation of the Earth's circumference using geometry and astronomical observations. Statement C is incorrect. The first known Greek astronomer to propose a heliocentric model of the solar system was Aristarchus of Samos in the 3rd century BC, predating Kepler and Newton by over a thousand years. Sir Isaac Newton (1643-1727) was a British physicist and mathematician, not Greek, and his work explained why planetary orbits are elliptical (gravity), building upon Kepler's descriptive laws. Statement D is correct. The Almagest is the 2nd- century AD astronomical treatise by Claudius Ptolemy, which presented a detailed geocentric model of the universe that remained the standard view for centuries.