Earth Science Concepts and Principles

Earth Science Concepts

• Earth science encompasses the geosphere, hydrosphere, atmosphere, and biosphere, encompassing everything from the core to the surface of the planet and the living organisms upon it.
• Heat originates from the Sun and from radioactive decay within the Earth.
• Density is a measure of mass per unit volume. Hotter objects have lower density than cooler ones.
• Gravity plays a role in maintaining the Earth's structure.
• The core is denser than the crust, which is denser than the mantle. Denser materials sink, and less-dense materials rise.
• Convection plays a significant role in the mantle and atmosphere, with heat transfer and fluid movement. For example, lava lamp convection.

Strengths of Science

• Scientific understanding is based on verifiable facts, physical objects, measurable data, and testable hypotheses, theories, and laws.
• Scientific theories and laws are continuously refined with new data.

Star Formation and Life Cycles

• Main Sequence Stars: Stars fuse hydrogen into helium in their cores; low-mass stars burn slowly for a longer time, while high-mass stars burn vigorously for a shorter time.
• Fate of Low-Mass Stars: Low mass stars eventually cool down to become a dwarf star.
• Fate of Intermediate-Mass Stars (like the sun): After the hydrogen runs out, the core collapses, causing the outer layers to expand into a red giant. The star then sheds its outer layers, creating a planetary nebula, and the core becomes a white dwarf.
• Fate of Massive Stars (more than 8x the sun's mass): Massive stars follow a different life cycle; they will explode in a supernova. The supernova outcome can be a neutron star or a black hole.

Limitations of Science

• Scientific inquiry is influenced by the personal backgrounds, biases, and interests of the scientists involved. These factors may affect the questions asked and how data is interpreted.

Formation of the Solar System

• The solar system originated from a rotating cloud of interstellar gas and dust (nebula).
• Gravity, collisions, and rotation caused the cloud to condense and collapse, creating a protostar at the center.
• Planetesimals formed from the remaining material, which accreted (grew larger) to become planets.

Planetesimals and Planets

• Inner rocky planets (Mercury, Venus, Earth, and Mars): are relatively dense and have a solid surface.
• Outer gas giant planets (Jupiter, Saturn, Uranus, and Neptune): are made mostly of gas and have many moons and rings.

Earth's Atmosphere and Oceans

• Earth's atmosphere likely originated through outgassing from the Earth's interior.
• Water vapor in the atmospheres of the early Earth condensed into the first oceans.
• The great oxidation event marks the beginning of oxygen in Earth's atmosphere.

Earth's Orbit, Tilt, and Eccentricity

• Earth's orbit around the Sun is not perfectly circular but slightly elliptical (eccentric).
• Earth's axis is tilted relative to its orbital plane, which causes seasonal changes in temperature.
• The wobble in Earth's axis (precession) changes the time of the year when specific parts of the Earth experience the most direct sunlight.

Meteoroids, Meteors, and Meteorites

• Meteoroids are small chunks of debris floating in space.
• Meteors are meteoroids that enter Earth's atmosphere and burn up, creating streaks of light.
• Meteorites are meteors that survive their passage through the atmosphere and land on Earth.

Weathering

• Weathering is the process that breaks down rocks.
• Mechanical weathering breaks rocks into smaller pieces without changing their chemical composition.
• Chemical weathering changes the chemical composition of rocks.