Astronomy Exam 3 Review: Terrestrial Planets, Jovian Systems, Moons, and Small Solar System Bodies

Comprehensive vocabulary flashcards covering Exam 3 lecture topics: terrestrial planetary geology (Venus and Mars), atmospheric evolution and the greenhouse effect, Jovian interior structures, weather and cloud layers, Galilean and Saturnian moons, and small bodies (dwarf planets, Kuiper Belt objects, and asteroids).

Differentiation

The geological process where gravity pulls high-density material (such as nickel and iron) down to the planetary interior while lower-density material rises toward the surface, organizing the interior into layers sorted by density.

Lithosphere

A planet's rigid, brittle outer layer consisting of the crust and uppermost mantle; a thin lithosphere is a prerequisite for active volcanism and tectonic fracture.

Volcanism

The geological process involving the eruption of molten rock (magma/lava) from a planet's interior onto its surface.

Tectonics

The fracturing of a planet's hard outer lithosphere into plates and their subsequent lateral or vertical movement driven by convective mantle motion beneath the surface.

Relative Crater Dating

A technique used to determine the age of planetary surfaces where heavily cratered areas (such as the lunar highlands at $4.1\text{--}4.3\,\text{billion years}$) represent older surfaces, while lightly cratered areas (such as Venus at $300\text{--}600\,\text{million years}$) represent geologically young, resurfaced crust.

Hot-Spot Volcanoes

Volcanoes formed when interior mantle plumes melt rock at the base of the lithosphere, forcing magma upward through cracks in the crust independently of plate boundaries; this process accounts for the widespread, even distribution of volcanoes on Venus.

Coronae (Venus)

Crown-shaped circular features on Venus produced by rising and subsequent receding plumes of subsurface magma that deform the crust with concentric fractures.

Lava Domes (Venus)

Pancake-shaped, flattened volcanic domes of wrinkled and cracked rock formed on the crust of Venus by the slow extrusion of viscous lava followed by cooling and subsidence.

Greenhouse Gas

An atmospheric molecule (such as $H_2O$, $CO_2$, or $CH_4$) that transmits incoming visible sunlight but absorbs and re-radiates outgoing infrared ($\text{IR}$) light emitted by the planet's surface.

Runaway Greenhouse Effect

A positive feedback process where higher surface temperatures accelerate ocean evaporation, releasing water vapor that increases infrared absorption, driving temperatures higher until solar ultraviolet light dissociates upper-atmosphere $H_2O$ and leaves a dense $CO_2$ atmosphere.

Runaway Refrigerator Effect

A reverse-greenhouse cooling process on Mars where atmospheric $CO_2$ dissolved into surface waters and chemically combined into carbonate rocks, thinning the atmosphere, weakening greenhouse warming, and causing remaining water to freeze underground.

Cerberus Fossae

A tectonic system of faults on Mars formed roughly $10\,\text{million years}$ ago when internal stresses pulled the surface crust apart.

Valles Marineris

A colossal canyon system on Mars wrapping roughly one-fifth of the way around the planet's equator, hypothesized to have originated from tectonic crustal tearing linked to magma upwelling at the Tharsis Bulge.

Tharsis Bulge

A massive, volcano-covered highland region on Mars created by a colossal upwelling of subterranean mantle plumes.

Olympus Mons

The largest shield volcano in the solar system, located on Mars, measuring $16\,\text{miles}$ ($22{,}500\,\text{m}$) high and $374\,\text{miles}$ ($600\,\text{km}$) wide, reaching its massive scale due to low surface gravity and the absence of plate tectonics.

Martian Dust Devils

Whirling atmospheric dust columns on Mars that can attain wind speeds up to $44\,\text{m/s}$ ($158\,\text{km/h}$), common during daytime in spring and summer, particularly clustered in dusty regions such as Amazonis Planitia.

Hematite Concretions (Moqui Marbles)

Spherical mineral-rich sandstone concretions found on Mars created by groundwater percolating through porous rock and depositing concentric layers of hematite, evidencing an ancient watery environment.

Conglomerates (Mars)

Sedimentary rocks observed on Mars consisting of rounded pebbles, cobbles, and boulders cemented together, whose smooth, worn edges indicate long-distance transport by liquid water.

Jezero Crater

An ancient impact basin on Mars preserving clay mineral deposits and river delta formations, serving as geological evidence of a past standing lake.

Recurring Slope Linea (RSL)

Narrow, dark seasonal markings that extend downhill along warm Martian slopes (such as inside Garni Crater and Coprates Chasma), pointing to contemporary briny fluid flows.

Gravitational Compression (Jovian Planets)

The physical process in gas giants where adding mass increases the gravitational weight of overlying layers, compressing the gas so that beyond $1\text{--}3\,\text{Jupiter masses}$, adding mass increases interior density rather than planet radius.

Metallic Hydrogen

A high-pressure liquid phase of hydrogen occurring deep inside Jupiter and Saturn where extreme compression forces electrons into a delocalized state, allowing the fluid to conduct electricity like a metal.

Great Red Spot

A colossal anticyclonic high-pressure storm on Jupiter twice the diameter of Earth, featuring sustained winds of $400\,\text{mph}$ and persisting for more than 300 years.

Ammonium Hydrosulfide Clouds ($NH_4SH$)

The intermediate cloud layer in Jupiter's atmosphere located below the colder ammonia layer, responsible for reflecting distinctive reddish and brownish colors.

Atmospheric Methane (Ice Giants)

A gas in the cold ($52\,\text{K}$) upper atmospheres of Uranus and Neptune that absorbs red wavelengths of sunlight while scattering and transmitting blue light back into space.

Jovian Belts and Zones

Alternating light and dark horizontal atmospheric bands produced by rapid planetary rotation and convection, where zones (light) are regions of rising warm gas forming white ammonia clouds and belts (dark) are regions of sinking cool gas.

Tidal Heating

Internal frictional heat generated within a moon by continuous gravitational flexing and distortion experienced as it travels through an eccentric orbit caused by orbital resonances with other moons.

Io

The innermost Galilean moon of Jupiter and the most volcanically active body in the Solar System, possessing high-temperature basaltic lava flows and sulfur dioxide ($SO_2$) geyser plumes driven by extreme tidal heating.

Europa

A Galilean moon of Jupiter with a bright, fracture-crisscrossed water-ice crust, minimal cratering, and a global liquid water ocean maintained beneath its icy shell by tidal heating.

Ganymede

The largest moon in the Solar System, possessing its own intrinsic magnetic field, a mixture of ancient dark cratered terrain and younger grooved terrain, and a probable subsurface water ocean.

Callisto

The outermost Galilean moon of Jupiter, characterized as a heavily cratered, geologically inactive ball of ice and rock that hosts the massive $4{,}000\,\text{km}$-diameter multi-ringed Valhalla impact basin.

Titan

Saturn's largest moon and the only moon in the Solar System with a thick atmosphere (primarily nitrogen with argon, methane, and ethane), supporting an active cycle of liquid methane rain, rivers, and surface lakes.

Enceladus

A small icy moon of Saturn with a subsurface global ocean that vents cryovolcanic water vapor and ice geysers through south-polar 'tiger stripe' fractures to continuously supply Saturn's diffuse E-ring.

Planet (IAU Definition)

A celestial body that satisfies three distinct criteria: (1) orbits the Sun directly, (2) is sufficiently massive for self-gravity to achieve hydrostatic equilibrium (nearly round shape), and (3) has cleared/dominated its orbital neighborhood.

Dwarf Planet

A celestial body that orbits the Sun and has reached hydrostatic equilibrium (spherical shape), but lacks sufficient mass to clear or dominate its orbital neighborhood and is not a moon (e.g., Pluto, Ceres).

Sputnik Planitia

A vast, uncratered basin on Pluto filled with a convective sheet of nitrogen glacier ice that slowly circulates above a possible deep underground liquid layer.

Wright Mons

A cryovolcanic feature on Pluto measuring $100\,\text{miles}$ wide and $13{,}000\,\text{feet}$ high, characterized by a $35\,\text{mile}$-wide central summit depression surrounded by concentric fractures.

Double Tidal Lock (Pluto-Charon)

A mutual gravitational synchronization where Pluto and its large moon Charon permanently display the exact same face toward one another while matching orbital and rotation periods of $6.387\,\text{days}$.

Arrokoth

A pristine, bi-lobed Kuiper Belt contact binary ($44.581\,\text{AU}$ from the Sun) visited by the New Horizons spacecraft on January 1, 2019, formed through the gentle coalescence of two ancient icy planetesimals.

C-type Asteroids

Carbonaceous asteroids composed of carbon-heavy rocks representing primitive, unprocessed planetesimal material with very dark, low-albedo surfaces.

S-type Asteroids

Silicate asteroids composed of stony minerals (silicon, oxygen, and other lighter elements) that display higher albedos and reflect visible sunlight efficiently.

M-type Asteroids

Metallic asteroids rich in nickel and iron, thought to originate from the shattered metallic cores of larger, differentiated planetesimals disrupted by collisions, appearing bright at radio frequencies.

Kirkwood Gaps

Depleted regions in the main asteroid belt corresponding to orbital resonances with Jupiter, where periodic gravitational perturbations systematically clear asteroids out of specific orbital periods.

Trojan Asteroids

Asteroids trapped at Jupiter's stable gravitational Lagrange points within its orbital plane, located $60^\circ$ ahead (L4, Greek camp) and $60^\circ$ behind (L5, Trojan camp) the planet.

Annie Jump Cannon

A prominent early-20th-century astronomer who pioneered the modern system of classifying stars according to their surface temperatures, cataloging over $350{,}000$ stars during her career.