Earth & Space Sciences – Regents Review (June ’25)

Vocabulary flashcards covering key terms, definitions, and concepts from the Earth & Space Sciences Regents notes.

Hertzsprung-Russell (H-R) diagram

A diagram that plots stars' luminosity (brightness) or absolute magnitude against their surface temperature, classifying stars by temperature and color.

Absolute magnitude

A measure of how bright a star would appear if all stars were the same distance from Earth; brighter stars have lower (more negative) values.

Spectral class

A star classification system (O, B, A, F, G, K, M) that groups stars by surface temperature and color; our Sun is class G.

Temperature (Kelvin, K)

A scale for measuring the surface temperature of stars; higher temperatures correspond to bluer colors.

Sun as a G-type star

The Sun is a spectral class G star with a surface temperature around 5,000–6,000 K and an absolute magnitude near 5.

Core (Sun)

The central region where thermonuclear fusion converts hydrogen into helium and releases energy.

Radiative Zone

A solar layer where energy is transported outward mainly by radiation (photons) rather than convection.

Convective Zone

A solar layer where energy is transported by convection currents of rising hot plasma and sinking cool plasma.

Photosphere

The visible surface of the Sun from which light is emitted.

Chromosphere

Layer above the photosphere where the density of plasma drops and temperatures change.

Transition Region

A thin layer separating the relatively cool chromosphere from the much hotter corona.

Corona

The Sun’s outer atmosphere, extending millions of kilometers into space.

Coronal Mass Ejection (CME)

A massive eruption of plasma and magnetic fields from the Sun’s corona.

Main sequence

A continuous and prolonged stage in a star’s life when hydrogen fusion occurs in the core; the Sun is currently here.

White dwarf

A dense stellar remnant left after a low- to medium-mass star exhausts its fuel; example: Sirius B.

Red giant

A late stage in stellar evolution where a star expands and cools after exhausting core hydrogen.

Nucleosynthesis

The process by which new atomic nuclei are produced in stars through nuclear fusion and related reactions.

Thermonuclear fusion

Fusion of light nuclei (e.g., hydrogen into helium) in a star’s core that releases energy.

Hubble’s Law

The relation that a galaxy’s recessional velocity increases with its distance from Earth, indicating the expansion of the universe.

Recessional velocity

The speed at which a galaxy moves away from Earth due to cosmic expansion.

Terrestrial planets

Rocky, compact planets: Mercury, Venus, Earth, Mars.

Jovian planets

Gas/ice giant planets: Jupiter, Saturn, Uranus, Neptune; large and have many moons.

Orbital period

The time required for a planet to complete one orbit around the Sun.

Saturn’s orbital period

Approximately 29.5 years (about 10,759 days) to orbit the Sun.

Obliquity

The tilt of Earth’s axis relative to the Sun; varies in a 41,000-year cycle, currently about 23.5°.

Obliquity minimum (22.1°)

The minimum tilt in the 41,000-year obliquity cycle, expected in about 9,800 years.

Eccentricity

A measure of how elliptical a planet’s orbit is (Mercury ~0.206, Venus ~0.007 in the notes’ table).

Greenhouse gas concentration (ppm)

The amount of CO2-equivalent gases in the atmosphere, measured in parts per million (ppm) for climate projections.

CO2 equivalent

A standardized measure expressing the impact of different greenhouse gases relative to CO2.

Ice-core data

Historical atmospheric CO2 and temperature records obtained from gas and dust trapped in ice cores.

Carbon cycle

The movement of carbon among reservoirs (atmosphere, biomass, soil, oceans, fossils) with fast (bio) and slow (geologic) components.

Fast carbon cycle

Carbon exchange involving living organisms and surface reservoirs (photosynthesis and respiration) on short timescales.

Slow carbon cycle

Carbon exchange involving soils and rocks (weathering, burial in sediments) over long timescales.

Megafires

Very large wildfires that release substantial amounts of CO2 into the atmosphere.

Forest fires and fossil fuels (carbon cycle model)

A representation showing how fires and burning fossil fuels add CO2 to the atmosphere and affect the carbon cycle.

Uranium-238 dating

Radiometric dating method using the decay of Uranium-238 to Lead-206 to determine rock ages.

Half-life

The time required for half of a radioactive substance to decay.

Radiometric dating

Dating rocks by measuring radioactive decay rates to estimate ages.

Horizon of the Sun’s energy transport (summary term)

Energy produced in the core diffuses outward through the radiative and convective zones before reaching the surface.

Sunspots

Dark, cooler regions on the Sun with intense magnetic fields; linked to the solar cycle about 11 years.

Maunder Minimum

A historical period (1645–1715) of very few sunspots, associated with cooler global temperatures.

Photons

Particular particles of light that carry energy away from the Sun through the photosphere.

Big Bang nucleosynthesis

Formation of light elements (H, He, Li, Be) in the early universe during the first minutes to minutes to hours after the Big Bang.

H–R diagram model interpretation

A tool used to infer stellar properties (temperature, brightness, evolution stage) from a star’s position.

Salt front

The leading edge of seawater entering a river estuary, where salinity rises above freshwater levels.

Estuary

A coastal area where freshwater from rivers mixes with saltwater from the sea; brackish water occurs here.

Salinity

The concentration of dissolved salts in water, often measured in mg/L or parts per thousand.

PCB (polychlorinated biphenyls)

Toxic industrial chemicals once dumped into rivers; associated with Superfund cleanup sites.

Superfund site

A polluted location designated by the EPA for cleanup due to hazardous wastes (e.g., PCBs in the Hudson River).

Dredging

The removal of contaminated sediments from water bodies to reduce pollution.

Radiometric dating (U–Pb, general)

Dating methods based on radioactive decay to determine geological ages.

Lithium mining (reservoir brine vs mining)

Two methods: mining (rock ore) and reservoir brine (evaporation ponds); differences in CO2 emissions, water use, and land use.

Evaporation ponds

Shallow pond systems used to concentrate lithium-bearing brine for extraction.

Green Pass (low-emission vehicles)

Port Authority toll discounts for low-emission vehicles (e.g., plug-in hybrids, battery EVs) during off-peak hours.

EN-ROADS

An online climate policy simulator used to explore outcomes of greenhouse gas scenarios and energy choices.

Ghost forest

Coastal forests killed by saltwater intrusion and rising sea levels, leaving dead trees and stumps; impacts carbon storage and ecosystem services.

Saltwater intrusion

Movement of saltwater into freshwater aquifers or estuarine areas due to sea-level rise or groundwater use.

Sea-level rise (global)

Increase in the average level of the world's oceans due to thermal expansion and added freshwater from ice melt.

Hotspot volcanism

A stationary mantle magma source that creates volcanic chains as tectonic plates move over it (e.g., Hawaii).

Mauna Loa, Kilauea, Loihi

Active volcanoes (Mauna Loa and Kilauea on the surface; Loihi an undersea volcano) over the Hawaiian hotspot.

Oceanic trench

A deep underwater trench formed at a subduction zone where one plate sinks beneath another.

Mid-ocean ridge

An underwater mountain range where new ocean crust is formed by plate tectonics.

Volcanic arc

A chain of volcanoes formed near subduction zones due to melting of subducted slab.

Continental vs oceanic crust

Continental crust is thick and buoyant; oceanic crust is thinner and more dense and sinks at subduction zones.

Radiometric dating (example use)

Used to determine the age of rocks and meteorites by radioactive decay dating (e.g., uranium–lead).