AST 103 - Exam 1 Astronomy | Eratosthenes Earth Measurement, Kepler Planetary Laws, Galileo Observations, Ptolemaic Model, Retrograde Motion, Sidereal Synodic Periods, Supernova Observations, Nebula Hypothesis, Condensation Accretion, Refractory Volatile

AST 103 - Exam 1 Astronomy | Eratosthenes Earth Measurement, Kepler Planetary Laws, Galileo Observations, Ptolemaic Model, Retrograde Motion, Sidereal Synodic Periods, Supernova Observations, Nebula Hypothesis, Condensation Accretion, Refractory Volatile Elements, CAIs Formation, Terrestrial Jovian Planet Formation, Frost Line, Solar System Dynamics, Orbital Mechanics, Optical Telescope Discoveries, Newton’s Laws, Force Net Outside Force, Planetary Rotation, Ecliptic Plane, Asteroid Belt, Giant Impact Moon, Grand Tack Model, Nice Model, Lunar Basins, Cosmic Calendar, Milky Way Structure, Astronomical Unit, Light-Year Conversion, Planetary Differentiation, Trojan Asteroids, Kuiper Belt, Late Heavy Bombardment Exam Questions Verified and Provided with Complete A+ Graded Rationales Latest Updated 2026 Eratosthenes 240 BC First to determine diameter of Earth, through studying shadows. Kepler 1609 Discovered the inner solar system (Sun, Mercury, Venus, Earth, and Mars). Galileo 1609 Discovered the solar system (up to Neptune). Orion Spur Where are we in the Milky Way? 10^13 km (On formula sheet) Speed of light is ~ 300,000 km/s, how long is a light year (in km)? A measurement of distance in the solar system. What is an astronomical unit? ~ 150,000,000 km (On the formula sheet) 1 AU = March (11 billion yrs) On the cosmic calendar, when was the Milky Way formed? August (4.5 billion yrs) On the cosmic calendar, when did the sun and planets form? December 25 (230 mil yrs) On the cosmic calendar, when did the dinosaurs appear? December 31 @ 11:52pm (200,000 yrs) On the cosmic calendar, when did modern humans appear? Geocentric and complicated. Describe the Ptolemaic Model.