Sun
The central star of our solar system, containing 99.86% of the total mass of the system.
Mercury
The closest planet to the Sun, with a heavily cratered surface and no atmosphere.
Venus
Often called Earth's "sister planet" with a thick atmosphere rich in carbon dioxide.
Earth
The only known planet with liquid water and a suitable atmosphere for life.
Astronomical Motion Science
Composition of the Solar System
The solar system consists of the Sun at its center, surrounded by eight planets, dwarf planets, moons, and countless asteroids and comets. The eight planets in order from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Planetary Motion Laws
Planets orbit the Sun in elliptical paths, with the Sun located at one focus of the ellipse. The closer a planet is to the Sun, the shorter its orbital period; the farther it is, the longer its orbital period.
Kepler's Laws
German astronomer Johannes Kepler discovered three fundamental laws of planetary motion:
- Law of Orbits: Each planet orbits the Sun in an elliptical path, with the Sun at one focus.
- Law of Areas: A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
- Law of Periods: The square of a planet's orbital period is proportional to the cube of the length of its orbit's semi-major axis.