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Solar System Overview

Sep 14, 2025

Overview

This lecture introduces the Solar System, its planets in order from the Sun, planetary orbits, and the origin of weekday names.

The Solar System

  • The Solar System is made up of the Sun and everything that revolves around it (planets, comets, asteroids).
  • The Sun is a star at the center of the Solar System.
  • Planets, comets, and asteroids all orbit the Sun.

The Planets of the Solar System

  • There are eight planets in the Solar System, listed in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
  • Mercury, Venus, Earth, and Mars are closer to the Sun and are smaller in size.
  • Jupiter, Saturn, Uranus, and Neptune are further from the Sun and are larger planets.
  • Jupiter is the largest planet in the Solar System.
  • The path a planet takes around the Sun is called an orbit.

The Days of the Week and Planetary Names

  • Monday is named after the Moon, Earth's natural satellite.
  • Tuesday, Wednesday, Thursday, and Friday are named after ancient British gods linked to Mars, Mercury, Jupiter, and Venus.
  • Saturday is named after Saturn.
  • Sunday is named after the Sun.

Key Terms & Definitions

  • Solar System — The Sun and all objects that move around it, including planets, comets, and asteroids.
  • Orbit — The path that a planet follows around the Sun.
  • Planet — A large celestial body that orbits the Sun.

Action Items / Next Steps

  • Memorize the order of the eight planets in the Solar System.
  • Review the connections between planet names and days of the week.