Regents Earth and Space Sciences Cheat Sheet.
The night-before summary, built like the exam.

The exam at a glance

Raw credits needed for a 65, by administration

• Read this carefully: the scale score is not a percentage. Fewer than half the credits has been enough to pass on every form published so far, and the conversion is re-set for every administration, so a chart from a previous exam must never be reused.

Blueprint weights

Plate tectonics and Earth's interior

• Divergent: new basaltic crust at mid-ocean ridges; symmetric age increase and mirrored magnetic stripes outward from the axis.
• Convergent, ocean-continent: subduction, trench, volcanic arc, deep earthquakes.
• Convergent, continent-continent: neither plate subducts; folded mountains and doubled crustal thickness.
• Transform: plates slide past; shallow earthquakes, no volcanism.
• P-waves travel through solid and liquid; S-waves stop at the liquid outer core, producing the S-wave shadow zone.
• Epicenter: the P-S arrival difference gives distance from one station only; three stations locate it.

Rocks, dating, and Earth history

• Crystal size: coarse means slow deep cooling; fine or glassy means fast surface cooling.
• Superposition: lower is older in undisturbed layers. Cross-cutting: the cut feature is younger than what it cuts.
• Unconformity: a buried erosional surface; touching layers can be millions of years apart.
• Half-lives: 1/2 left = 1 half-life, 1/4 = 2, 1/8 = 3, 1/16 = 4. Match the isotope to the age — carbon-14 for recent organic material, uranium-238 for ancient rock.
• Index fossil: short time range, wide geographic range.
• New York specifics: Devonian marine fossils in western NY record a shallow inland sea; the Finger Lakes are glacially deepened north-south stream valleys.

Space systems

• Seasons: caused by the 23.5-degree axial tilt changing noon Sun altitude and daylight hours — not by distance. Opposite seasons in the two hemispheres is the killer counter-argument.
• Noon Sun altitude = 90 minus the angular distance between your latitude and the subsolar latitude.
• Eclipses: rare because the Moon's orbit is tilted about five degrees; they need a node alignment as well as the right phase.
• Kepler: equal areas in equal times means fastest at perihelion, slowest at aphelion.
• Redshift rising with distance = expanding universe. 2.7 K cosmic microwave background = cooled relic radiation.
• H-R diagram: upper right = luminous and cool = giants; lower left = hot and faint = white dwarfs.
• Sun-mass star: red giant, planetary nebula, white dwarf. Elements heavier than iron come from supernovae and neutron-star mergers.

Weather and climate

• Small temperature-dewpoint spread = near saturation = fog, dew, or cloud likely.
• Closely spaced isobars = steep pressure gradient = stronger wind.
• Cold front: steep uplift, narrow band of storms, then cooler and clearer. Warm front: gentle uplift, wide band of steady precipitation.
• Occluded front: triangles and semicircles on the same side of the line.
• Northern Hemisphere low: counterclockwise and inward, rising air; high: clockwise and outward, sinking air.
• Rain shadow: air dries rising over the range, then warms and dries further descending the lee side.
• Greenhouse effect: shortwave in, longwave absorbed and re-emitted downward. Ice-albedo feedback amplifies Arctic warming.

Human sustainability

• Paving a watershed: less infiltration, more runoff, higher and faster flood peaks.
• Over-pumping an aquifer: falling water table, dry shallow wells, possible permanent subsidence.
• Ocean acidification: dissolved carbon dioxide lowers pH and reduces carbonate ions for shell builders.
• Nature-based defence (marshes, dunes) regenerates itself; engineered defence (seawalls, pumps) needs maintenance.
• Liquefaction risk: loose saturated sediment amplifies shaking and can lose strength entirely.
• Reservoirs lose storage to sedimentation and starve downstream deltas.

Answering clusters

• Read every stimulus in a cluster once, properly — four or five questions depend on it.
• Answers within a cluster build on each other; finish a hard cluster rather than abandoning the context.
• Constructed-response answers go in the booklet, multiple-choice on the separate answer sheet. Pen, except pencil for graphs and drawings.
• Answer the question actually asked, in one or two sentences. Never leave a blank — the cut score is well under half the credits.
• Sign the declaration on the answer sheet; an unsigned sheet cannot be accepted.