Earth System, Solar System, and the Universe

Earth's Motion

• Three Independent Motions:
  • Daily Rotation: 24 hours to spin around its axis, tilted at 23.5 degrees.
  • Yearly Revolution: Around 365 days to orbit the Sun.
  • Wobble: Minor axis wobble affecting magnetic poles.
• Unequal revolution around the Sun; Earth is closer to the Sun during winter.

Seasons and Celestial Phenomena

• Equinoxes: Equal day and night (12 hours each) globally.
• Solstices:
  • Summer Solstice: 24 hours of daylight or darkness at high latitudes.
• Moon Phases: Varies by hemisphere; moon's rotation synchronized with its orbit (we see one side only).

Moon

• Impact on Earth:
  • Gravitational pull causes tides.
• Theories of Formation: Formed simultaneously with Earth or from asteroid impact.
• Lunar Conditions: No atmosphere; basaltic rock dating 4 billion years old.

Eclipses

• Solar Eclipse: Moon blocks the Sun.
• Lunar Eclipse: Earth blocks the Moon's light.
• Types of Eclipses: Total and partial (depending on observer's location).

Solar System

• Planetary Order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune (Pluto is a dwarf planet).
• Planets and Moons: Moons vary in size; some larger than planets (e.g., Saturn's Titan).
• Astronomical Units: Distance from Earth to Sun (93 million miles) is 1 AU.

Smaller Solar System Bodies

• Comets: Origin from the Oort Cloud and Kuiper Belt; tails face away from Sun.
• Asteroids: Mostly between Mars and Jupiter; could be parts of a failed planet.
• Meteoroids, Meteors, Meteorites:
  • Meteoroid in space.
  • Meteor burns in atmosphere.
  • Meteorite impacts Earth.

Formation of Solar System

• Nebula Theory: Solar system formed from a nebular cloud; heavier elements towards the center.
• Protosun and Planets: Formed from gravitational contraction and spin.

Stars and Universe

• Celestial Sphere: Imaginary sphere projecting Earth's perspective of stars.
• Star Properties: Emit own light; twinkle due to atmospheric dust.
• HR Diagram: Shows star life cycles, temperature, and luminosity.
• Star Lifecycles: Main-sequence to red giants/white dwarfs based on mass.

Galaxy and Universe

• Milky Way: Our spiral galaxy.
• Big Bang Theory: Universe's expansion supports this theory; galaxies moving apart like dough expanding.
• Multiverse Theory: Potential for multiple universes from singularities.

Important Concepts

• Doppler Effect in Astronomy: Used to determine star movements.
• Star Spectra: Analyze luminosity and distance.
• Apparent vs. Intrinsic Magnitude: Brightness as seen from Earth vs. actual brightness.