Earth Science Introduction and Basics

Earth Science Introduction

• Earth science encompasses geosphere (rocks, minerals, core), hydrosphere (water), atmosphere (weather), and biosphere (all life).
• Heat sources include the sun, space, and radioactive decay within Earth.
• Density is equal mass divided by volume, influencing Earth's layers.
• Substances solidify at different temperatures, denser layers at the core.
• Heat reduces density; hotter objects have lower density.
• Convection in the mantle (hot rising, cool sinking) drives hotspots.
• Convection in the atmosphere is demonstrated by hot air rising and cooling to form clouds.

Strengths of Science

• Science is based on facts, physical objects, and observations.
• Hypotheses, theories, and laws must be testable with data.
• Astronomy is a science making predictions; astrology is not science.

Main Sequence Star Stage

• Low-mass stars (less than half the sun's mass) burn slowly and never become red giants.
• After hydrogen depletion, they cool into dwarf stars.
• Intermediate-mass stars (like our sun) eventually run out of hydrogen, enlarge, and become red giants, then cool to dwarf stars.

Fate of Massive Stars

• Stars greater than 8 times the sun's mass experience core collapse and supernova explosions.
• These explosions result in either a neutron star or a black hole; remnants.

Limitations of Space

• The personal backgrounds of scientists influence their research questions and interpretations of data.
• Bias, interests, and experiences shape science.

Nuclear Fusion

• Stars fuse hydrogen into helium and other elements.
• Stellar classification is based on luminosity, color, and temperature.

Star Brightness

• Brightness is related to temperature; hotter stars are brighter and blue.
• Hertzsprung-Russell diagrams classify stars.

Molecular Clouds

• Regions of dense gas and dust where stars are born.
• Gravity pulls matter together, creating extreme heat to form protostars.

Formation of the Solar System

• Solar nebula hypothesis describes the formation of the sun and planets from an interstellar cloud.
• This cloud collapses and rotates, forming a flattened disk.
• Smaller objects condense and accumulate to form planets and other bodies.

Inner Rocky Planets vs. Outer Gas Giants

• Inner planets are smaller, denser, and rock-and-metal based.
• Outer planets have lower density and are primarily hydrogen, helium, and hydrogen compounds.

Formation of Planetary Layers

• Planetary layers differentiate as planets cool.
• Dense materials sink to the center and less dense materials rise.

The Crust, Mantle, and Core

• Crust is the outermost, less dense, and brittle layer.
• Mantle is beneath the crust, less dense than the core, and dense rocks.
• The core is the innermost layer having the highest density consisting of iron and nickel.

Origin of Atmosphere, Oceans, and Life

• The early atmosphere was formed through outgassing.
• Water vapor condensed to form oceans.
• Early life may have appeared about 2.45 billion years ago.

Eccentricity and Shape of Earth's Orbit

• Earth's orbit cycles between high and low eccentricity.
• Low eccentricity means a more circular orbit.

Origin of the Moon

• The giant-impact hypothesis proposes a Mars-sized object collided with early Earth.
• The resulting debris formed the Moon.

Asteroids and Comets

• Asteroids are rocky objects that orbit between Mars and Jupiter (Asteroid Belt).
• Comets are icy objects in the outer solar system (Kuiper Belt, Oort Cloud).

Meteoroids, Meteors, and Meteorites

• Meteoroids are small chunks of debris in space.
• Meteors are meteoroids that enter Earth's atmosphere and burn up.
• Meteorites are meteors that survive the atmosphere and land on Earth.
• Weathering involves mechanical processes of breaking down rocks into smaller pieces.