Moon Case Study and Solar System Formation Notes

Moon Case Study: Surface Features and Space Exploration

• Regolith: Fine dust covering the Moon's surface.
• Craters: Formed by meteoroid impacts (e.g., Tycho Crater).
• Maria: Dark, smooth ancient lava plains (Latin for "seas"), formed by volcanic activity billions of years ago.
• Highlands: Lighter-colored, heavily cratered mountains, older than the maria.
• Rilles: Narrow valleys or trenches, likely caused by collapsed lava tubes or crust movements.
• Luna 2 (Soviet Union, 1959): First spacecraft to impact the Moon.
• Luna 9 (Soviet Union, 1966): First soft landing on the Moon.
• Apollo 11 (NASA, 1969): First human landing on the Moon.
  • Astronauts: Neil Armstrong and Buzz Aldrin.
  • Activities: Collected rock samples, set up scientific equipment.
• Apollo Missions (1969-1972): 12 astronauts walked on the Moon during six missions.
• Current Missions: NASA's Artemis program and other international efforts are preparing to return humans to the Moon and build permanent lunar bases, possibly leading the way for Mars exploration.

Formation of the Solar System

• Nebula: Giant cloud of gas and dust (hydrogen, helium, rock, metals) in space from which the solar system formed about 4.6 billion years ago.
• Nebula Collapse: A powerful event (e.g., supernova explosion) shocked the cloud, causing it to collapse.
• Spinning Disk Formation: As the nebula collapsed, it began to spin faster and flatten into a swirling disk.
• Sun Formation: Gravity pulled most of the mass toward the center of the disk. The center became very hot and dense, igniting nuclear fusion, thus forming the Sun.
• Nuclear Fusion: Hydrogen atoms combine under high pressure and temperature to form helium, releasing a huge amount of energy.
• Accretion: The remaining gas and dust in the disk started to clump together through accretion, where tiny particles stick together to form larger bodies.
• Planetesimals: Clumps formed through accretion grew into planetesimals.
• Planet Formation: Planetesimals eventually grew into the planets, moons, and other objects in our solar system.

Composition of the Sun and Planets

• Sun Composition: Mostly hydrogen (about 74%) and helium (about 24%), with small amounts of heavier elements. The Sun contains over 99% of the total mass of the solar system.
• Inner Planets (Mercury, Venus, Earth, Mars): Made mainly of rock and metal, which stayed solid in the hot, inner solar system.
• Outer Planets (Jupiter, Saturn, Uranus, Neptune): Made of lighter gases like hydrogen, helium, methane, and ammonia, which were able to stay cool and collect in the outer, colder parts of the solar system.

Scientific Study Methods

• Telescopes and Spacecraft: Used to study the composition of planets and the Sun.
• Spectroscopy: Analyzes the light from stars and planets to determine the elements present. Different elements absorb and emit specific wavelengths of light, like fingerprints.
• Space Probes and Rovers: Visit planets and moons, taking samples and photos to understand surface materials, gases, and weather.

Inner vs. Outer Planets

• Inner Planets (Terrestrial): Mercury, Venus, Earth, Mars.
  • Small, rocky worlds formed close to the Sun.
  • Solid surfaces, few or no moons, no rings.
• Outer Planets (Gas/Ice Giants): Jupiter, Saturn, Uranus, Neptune.
  • Much larger, made mostly of gas and ice.
  • Formed in colder parts of the solar system, collecting light gases (hydrogen and helium).
  • Many moons, thick atmospheres, and ring systems.

Table of Comparison

Key Concepts Revisited

• Accretion: Process where small particles stick together to form planets.
• Nuclear Fusion: Process where hydrogen atoms combine under high pressure and temperature to form helium, releasing energy in the Sun.
• Spectroscopy: Method used to determine the composition of planets and stars by analyzing light.