1) Egyptians studied stars like Sirius to predict the Nile River's flooding and Mayans developed an advanced calendar by observing solstices, while people who built Stonehenge may have used it to track solstices. 2) Greeks were the first to observe and name the five planets and Aristotle proposed a geocentric model with Earth at the center surrounded by crystalline spheres, which Ptolemy later refined with epicycles to explain planetary motion. 3) Copernicus published his theory that introduced heliocentrism, with the sun at the center, just before he died, revolutionizing the understanding of the solar system.

1. Exploration: How new knowledge has led to our current view of the solar system. EQ: How has mankind’s need to explore led to our current view of the solar system?

13. Copernican Solar System