Space (Physics)

Overview of the Solar System

• The Solar System consists of objects orbiting the Sun, the sole star and main mass contributor.
• Eight planets are categorized into two groups: inner rocky planets (Mercury, Venus, Earth, Mars) and outer gas giants (Jupiter, Saturn, Uranus, Neptune).
• Additional objects include dwarf planets (e.g., Pluto), asteroids, moons, comets, and natural satellites.

Formation of the Solar System

• The Solar System formed approximately 4.6 billion years ago from a rotating cloud of gas and dust which collapsed into an accretion disc.
• The Sun was formed at the center, with planets emerging from residual material.

Planetary Orbits and Motion

• Planetary orbits are elliptical, leading to varying distances from the Sun throughout their orbits.
• Orbital period refers to the time taken for a planet to complete one full orbit around the Sun.

Electromagnetic Radiation from the Sun

• The Sun emits electromagnetic radiation traveling at a speed of 3.0 x 10^8 m/s.
• Types of radiation include visible light, infrared, ultraviolet, X-rays, and gamma rays.

Light Travel Times

• Light takes about 8 minutes to travel from the Sun to Earth and approximately 5 hours to reach Pluto.

Gravitational Forces

• Gravitational force holds planets in orbit, dependent on their masses and distance from each other.
• Stronger gravitational pull closer to the Sun, leading to faster planetary orbits; weaker pull results in slower orbits.

Characteristics of the Planets

• Mercury, closest to the Sun, orbits at an average speed of 47 km/s; Neptune, farthest, orbits at 5 km/s.

Planetary Data Summary

• Orbital data for planets include:
  • Mercury: Distance 57.9 million km, Duration 88 days, Density 5429 kg/m³, Temperature 167°C, Gravity 3.7 m/s².
  • Venus: Distance 108.2 million km, Duration 224.7 days, Density 5243 kg/m³, Temperature 464°C, Gravity 8.9 m/s².
  • Earth: Distance 149.6 million km, Duration 365.2 days, Density 5514 kg/m³, Temperature 15°C, Gravity 9.8 m/s².
  • Mars: Distance 228.0 million km, Duration 687 days, Density 3934 kg/m³, Temperature -65°C, Gravity 3.7 m/s².
  • Jupiter: Distance 778.5 million km, Duration 4331 days, Density 1326 kg/m³, Temperature -110°C, Gravity 23.1 m/s².
  • Saturn: Distance 1432.0 million km, Duration 10747 days, Density 687 kg/m³, Temperature -140°C, Gravity 9.0 m/s².
  • Uranus: Distance 2867.0 million km, Duration 30589 days, Density 1270 kg/m³, Temperature -195°C, Gravity 8.7 m/s².
  • Neptune: Distance 4515.0 million km, Duration 59800 days, Density 1638 kg/m³, Temperature -200°C, Gravity 11.0 m/s².

Orbital Features

• Planets experience points called perihelion (closest point to the Sun) and aphelion (farthest point).
• Eccentricity of orbits indicates shape; higher eccentricity suggests more oval orbits.
• Mars has a more eccentric orbit compared to Earth with distances varying significantly from the Sun.

Energy Dynamics in Orbits

• Closer proximity to the Sun results in higher kinetic energy and lower potential energy; vice versa when farther away.
• The total energy in a planet's orbit is constant, illustrating the balance between kinetic and potential energy as a planet's distance from the Sun changes.