CSET Earth & Space Sciences (219) cheat sheet

Kepler's third law: P² = a³ when period P is in years and semi-major axis a is in astronomical units; this applies to any object orbiting the Sun.

Stellar spectral sequence OBAFGKM runs hot to cool; each spectral class is subdivided 0–9, so A0 is hotter than A5.

Hertzsprung–Russell diagram: main sequence runs lower-right (cool, dim) to upper-left (hot, luminous); giants and supergiants lie upper-right, white dwarfs lower-left.

Doppler shift: recession gives redshift (λ observed > λ rest); approaching gives blueshift; radial velocity v = c·Δλ/λ for v much less than c.

Solar system formation: nebular hypothesis - collapsing molecular cloud, rotating disk, accretion of planetesimals, inner rocky planets, outer ice giants and gas giants beyond the frost line.

Lunar phases repeat about every 29.5 days (synodic month); sidereal month is about 27.3 days; solar eclipses require new moon near a node, lunar eclipses require full moon near a node.

Seasons result from Earth's 23.4° axial tilt changing solar insolation angle and day length, not from varying Earth–Sun distance.

Absolute magnitude is intrinsic brightness at a standard distance of 10 parsecs; apparent magnitude depends on distance, with lower magnitude numbers meaning brighter objects.

Earth's internal layers by composition: crust (oceanic basalt, continental granite), mantle (peridotite), core (iron–nickel); by physical state: lithosphere, asthenosphere, mesosphere, outer core (liquid), inner core (solid).

Seismic waves: P waves are compressional and travel through solids and liquids; S waves are shear waves that cannot pass through liquids, which is how the liquid outer core was inferred.

Mohorovičić discontinuity separates crust from mantle; the Gutenberg discontinuity separates mantle from core; the Lehmann discontinuity lies within the core.

Bowen's reaction series: discontinuous branch olivine → pyroxene → amphibole → biotite; continuous branch plagioclase feldspar from calcic to sodic; quartz and K-feldspar crystallize last.

Igneous classification by silica: felsic (high silica, quartz/orthoclase), intermediate, mafic (low silica, olivine/pyroxene); mafic magma is less viscous and less explosive.

Plate boundaries: divergent (mid-ocean ridge, rift), convergent (subduction, continental collision), transform (strike-slip); earthquakes concentrate at all three, volcanoes mainly at convergent and divergent boundaries.

Rock cycle: weathering and erosion produce sediment; compaction and cementation make sedimentary rock; heat and pressure make metamorphic rock; melting and cooling make igneous rock.

Mineral identification uses hardness (Mohs scale 1 talc to 10 diamond), cleavage, luster, streak, and specific gravity; calcite fizzes in dilute HCl.

Atmospheric composition: about 78% nitrogen, 21% oxygen, 0.93% argon, and roughly 0.04% carbon dioxide, plus variable water vapor.

Troposphere temperature decreases with altitude at about 6.5 °C per km; stratosphere warms with altitude because ozone absorbs ultraviolet radiation; mesosphere cools upward.

Coriolis effect deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; it is zero at the equator and strongest at the poles.

Global circulation cells: Hadley (0–30°), Ferrel (30–60°), Polar (60–90°); surface winds are trade winds, westerlies, and polar easterlies.

Relative humidity is the ratio of actual vapor pressure to saturation vapor pressure; dew point is the temperature at which air reaches saturation.

Air masses are classified by source region: continental (dry) or maritime (moist), and polar, tropical, or arctic; fronts are cold, warm, stationary, or occluded.

Ocean circulation: surface currents are wind-driven gyres; deep thermohaline circulation is driven by temperature and salinity differences; upwelling brings cold, nutrient-rich water.

Water cycle fluxes: evaporation and transpiration add vapor, condensation forms clouds, precipitation returns water, and runoff and infiltration move water across and into the ground.

Relative dating principles: superposition (older below), original horizontality, lateral continuity, cross-cutting relationships (younger features cut older), and inclusions (included fragments are older).

Unconformities: angular (tilted layers eroded then overlain), disconformity (erosion surface between parallel layers), and nonconformity (sedimentary rock over igneous or metamorphic rock).

Radiometric dating uses the decay equation N = N₀e^(−λt) with half-life t½ = ln2/λ; useful parent–daughter pairs include U-238/Pb-206, K-40/Ar-40, and C-14/N-14.

Carbon-14 dating is limited to organic material younger than roughly 50,000 years; older rocks require long-lived isotopes.

Geologic time scale order: Hadean, Archean, Proterozoic, then Phanerozoic with Paleozoic, Mesozoic, and Cenozoic eras; the Cenozoic includes Paleogene, Neogene, and Quaternary periods.

Major extinctions: end-Ordovician, Late Devonian, end-Permian (largest, about 252 Ma), end-Triassic, and end-Cretaceous (about 66 Ma, linked to the Chicxulub impact).

Fossilization favors hard parts, rapid burial, low oxygen, and stable chemical conditions; index fossils are widespread, short-ranging, and easily identified for correlation.

Fossil succession records evolution: trilobites dominate the Paleozoic, dinosaurs and ammonites the Mesozoic, and mammals and grasses the Cenozoic.

NGSS disciplinary core ideas in this domain include ESS1 (Earth's place in the universe), ESS2 (Earth's systems), and ESS3 (Earth and human activity).

Science and engineering practices include developing models, analyzing data, constructing explanations, and engaging in argument from evidence.

Crosscutting concepts include patterns, cause and effect, scale and proportion, systems and system models, energy and matter flows, and stability and change.

Three-dimensional learning means combining disciplinary core ideas, science and engineering practices, and crosscutting concepts within a lesson.

Common misconceptions to address: seasons caused by Earth's distance from the Sun; the Moon's phases caused by Earth's shadow; groundwater existing as underground rivers or lakes.

Modeling scale: Earth–Moon and Earth–Sun distances are often compressed in classroom models; emphasize that most of the solar system is empty space.

Inquiry and safety: hands-on activities should use safe materials, clear procedures, and student-generated questions, with data recorded and analyzed to support claims.

Assessment should include phenomena-based tasks and explanation from evidence, not only recall of vocabulary terms.