OAE Earth and Space Science cheat sheet

Scientific inquiry cycle: observation → question → hypothesis → prediction → test → analysis → revision; hypotheses must be falsifiable and testable.

Independent variable is manipulated; dependent variable is measured; controlled variables are held constant to isolate cause and effect.

A theory is a well-tested explanatory framework supported by multiple lines of evidence (e.g., plate tectonics, evolution); a law describes a consistent relationship (e.g., Newton's law of gravitation). Neither is a guess.

Reliability increases with repeated trials and larger samples; validity means the design actually measures the intended quantity.

Correlation does not establish causation; a controlled experiment or a natural experiment with a plausible mechanism strengthens causal claims.

Earth and space science relies on indirect evidence: seismic waves, isotope ratios, spectra, and remote sensing because direct sampling is limited.

Deep time and large spatial scales require uniformitarianism plus catastrophism: present processes plus rare high-energy events explain the rock record.

Peer review, replication, and open data are the social mechanisms that filter error; scientific claims are provisional and revised with new evidence.

Measurement precision is limited by instrument resolution; report uncertainty and significant figures consistent with that precision.

Earth's layers by composition: crust (oceanic ~5-10 km, continental ~30-70 km), mantle (to ~2900 km), core (iron-nickel, to ~6371 km).

By physical properties: lithosphere (rigid, crust plus uppermost mantle), asthenosphere (ductile, ~100-350 km), mesosphere, outer core (liquid, generates the geodynamo), inner core (solid).

P-wave velocity drops and S-waves disappear at the core-mantle boundary, proving the outer core is liquid; the Moho marks the crust-mantle boundary.

Isostasy: buoyant lithosphere floats on the asthenosphere; thicker or less dense crust rides higher, explaining mountain roots and post-glacial rebound.

Plate tectonics: divergent boundaries create new crust (mid-ocean ridges), convergent boundaries destroy or thicken crust (subduction, collision), transform boundaries slide past.

Seafloor magnetic striping symmetric about ridges records geomagnetic reversals and supports seafloor spreading; ages increase away from ridges.

Mantle convection and slab pull drive plates; ridge push and basal drag are secondary forces.

Earthquake focus depth and first-motion data locate faults; shallow quakes at ridges, deep quakes in subducting slabs.

Radioactive decay (U-238, K-40, Rb-87) supplies internal heat, driving convection and the geodynamo.

Weathering breaks rock in place (physical: frost wedging, exfoliation; chemical: hydrolysis, oxidation, dissolution); erosion transports the products.

Stream power depends on discharge and gradient; competence is the largest clast moved, capacity is the total load; deposition occurs when velocity falls.

V-shaped valleys form by fluvial incision; U-shaped valleys and moraines indicate glacial erosion and deposition.

Karst landscapes form where soluble limestone dissolves, producing caves, sinkholes, and disappearing streams.

Mass wasting is classified by material and motion (creep, slump, debris flow, rockfall) and triggered by water, slope steepening, or earthquakes.

Wind erodes by deflation and abrasion, producing ventifacts, yardangs, and dunes; dune type (barchan, transverse, longitudinal) reflects wind and sand supply.

Wave refraction concentrates energy on headlands and erodes them; longshore drift moves sediment along coasts, building spits and barrier islands.

Soils form from parent material, climate, organisms, topography, and time (CLORPT); horizons O, A, E, B, C, R develop with leaching.

Drainage patterns reflect bedrock: dendritic in uniform rock, trellis in folded strata, radial around domes, rectangular along joint sets.

Atmospheric composition: ~78% N2, ~21% O2, ~0.93% Ar, ~0.04% CO2; water vapor varies 0-4% and drives latent heat transfer.

Layers by temperature profile: troposphere (lapse rate ~6.5 °C/km), stratosphere (ozone heating), mesosphere, thermosphere, exosphere.

Pressure decreases exponentially with altitude; the Coriolis effect deflects moving air right in the Northern Hemisphere and left in the Southern, strongest at poles.

Cloud formation requires condensation nuclei, cooling to the dew point, and saturation; adiabatic cooling with ascent produces clouds and precipitation.

Mid-latitude cyclones form along the polar front with warm and cold fronts; cold fronts produce narrow, intense bands, warm fronts broad, gentle precipitation.

Thunderstorms require instability, moisture, and lift; tornadoes form in rotating supercells, and hurricanes need sea surface temperatures ≥26.5 °C and low wind shear.

Climate vs. weather: climate is long-term statistics; Milankovitch cycles, solar output, albedo, and greenhouse gases control climate over different timescales.

Greenhouse gases absorb and re-emit infrared radiation; CO2, CH4, N2O, and water vapor are the principal absorbers.

El Niño (warm eastern Pacific, weakened trade winds) and La Niña (cool eastern Pacific) shift global precipitation and storm tracks.

Water distribution: ~97.5% saline ocean, ~2.5% freshwater; of freshwater, ~69% glaciers and ice caps, ~30% groundwater, <1% surface water.

The hydrologic cycle transfers water by evaporation, transpiration, condensation, precipitation, infiltration, runoff, and groundwater flow.

Porosity is the fraction of void space; permeability is the ability to transmit fluid; a confining layer (aquitard) restricts flow.

An aquifer is unconfined when bounded by a water table, confined when bounded by aquitards; artesian wells flow where the potentiometric surface exceeds land elevation.

Groundwater flows from high hydraulic head to low; Darcy's law: Q = K·A·(Δh/ΔL).

Ocean circulation includes wind-driven surface gyres and thermohaline deep circulation driven by temperature and salinity; upwelling brings nutrient-rich water to the surface.

Glaciers form where accumulation exceeds ablation; they flow by internal deformation and basal sliding, and retreat when mass balance is negative.

Sea level rises from thermal expansion, glacier and ice-sheet melt, and land subsidence; ice cores and tree rings provide paleoclimate proxies.

Watersheds (drainage basins) collect precipitation and route it to a common outlet; land use and impervious surfaces alter hydrographs.

Earth's rotation (23 h 56 m sidereal) causes day and night; revolution (365.25 days) and 23.5° axial tilt cause seasons.

Moon phases result from the changing angle between Earth, Moon, and Sun; a synodic month (29.5 days) exceeds the sidereal month (27.3 days).

Solar and lunar eclipses occur only near syzygy when the Moon's orbital plane (inclined ~5°) crosses the ecliptic at nodes.

Kepler's laws: elliptical orbits with the Sun at one focus; equal areas in equal times; P² ∝ a³ (P in years, a in AU).

Newton's law of gravitation: F = G·m1·m2/r²; it explains orbits, tides, and the barycenter of the Earth-Moon system.

Solar structure: core (fusion), radiative zone, convective zone, photosphere, chromosphere, corona; sunspots follow an ~11-year cycle.

Solar system formation from a rotating nebula: inner rocky planets, outer gas and ice giants, plus asteroid belt, Kuiper belt, and Oort cloud.

Tides result from differential gravitational pull; spring tides at new and full moon, neap tides at quarter moons.

Terrestrial planets have high density and thin or no atmospheres; Jovian planets have low density, thick hydrogen-helium atmospheres, and many moons.

Hertzsprung-Russell diagram plots luminosity vs. temperature; main sequence runs from hot, luminous O stars to cool, dim M stars.

Stellar fusion: proton-proton chain in Sun-like stars; CNO cycle in hotter stars; heavier elements form through fusion up to iron, then via supernovae.

Stellar evolution depends on mass: low-mass stars become white dwarfs, intermediate become neutron stars, high-mass become black holes.

Stellar parallax measures distance to nearby stars; standard candles (Cepheids, Type Ia supernovae) extend the distance ladder.

Spectral classification OBAFGKM by temperature; absorption lines indicate composition and ionization state.

Galaxies: spiral, elliptical, irregular; the Milky Way is a barred spiral with a supermassive black hole at its center.

Hubble's law: v = H0·d, with H0 ≈ 70 km/s/Mpc; recession velocity increases with distance, evidence for cosmic expansion.

Big Bang evidence: cosmic microwave background, primordial element abundances, and redshift of distant galaxies.

Dark matter and dark energy dominate the mass-energy budget; dark energy drives accelerating expansion.

Three-dimensional learning aligns disciplinary core ideas, science and engineering practices, and crosscutting concepts (e.g., patterns, cause and effect, systems).

Inquiry-based instruction uses phenomena to drive questions; students construct explanations from evidence rather than memorize facts.

Formative assessment informs instruction in real time (exit tickets, questioning, concept maps); summative assessment evaluates learning at the end of a unit.

Rubrics should describe observable performance levels aligned to learning objectives; inter-rater reliability improves with shared scoring practice.

Misconceptions (e.g., seasons caused by distance from the Sun, Moon phases caused by Earth's shadow) require targeted conceptual-change instruction.

Modeling (physical, conceptual, mathematical) and data analysis build representational competence; students should evaluate model limitations.

Safety and ethics: lab safety plans, appropriate handling of samples and equipment, and ethical use of data and sources.

Differentiation and universal design support diverse learners through multiple representations, scaffolded tasks, and accessible materials.

Assessment items should be aligned to standards, free of bias, and include distractor analysis to reveal misconceptions.