Astronomy Midterm

Importance of Studying Asteroids

Clues to Solar System formation and Earth impact risk assessment. Mnemonic: "Asteroids: Ancient & Alarming"

Locations of Icy Bodies

Kuiper Belt (beyond Neptune) and Oort Cloud (distant spherical shell). Mnemonic: "Kuiper Close, Oort Out"

Three Asteroid Locations

Main Belt (Mars-Jupiter), Near-Earth Objects (NEOs), Jupiter Trojans (L4/L5). Mnemonic: "Main, Near, Jupiter"

Solar Nebula Theory Evidence

Flat planetary orbits and rocky inner/icy outer planet composition. Mnemonic: "Flat Disk, Sorted Stuff"

Comet Changes Near the Sun

Nucleus sublimates into coma; solar wind forms dust/ion tails pointing away from Sun. Mnemonic: "Sun Heat = Tail Street"

Effects of Earth's Revolution

Seasonal constellation shifts and changing sunrise/sunset times. Mnemonic: "Orbit Shifts Sky & Time"

Challenges of Venus Landers

Extreme heat (467°C) and pressure (90 atm) destroy equipment rapidly. Mnemonic: "Venus: Pressure Cooker"

Early Solar System Temperature and Chemistry

Inner zone: refractory metals/silicates; outer zone: volatile ices/gases. Mnemonic: "Hot Rocks, Cold Ices"

Leading Moon Formation Theory

Giant Impact: Mars-sized body collision ejected Moon-forming debris. Mnemonic: "Big Splash, Lunar Crash"

Convection and Examples

Earth’s mantle (plate tectonics) and Sun’s surface (granulation). Mnemonic: "Boiling Rock, Bubbling Light"

Causes of Lunar Phases

Changing visible Sun-lit portion during Moon’s orbit around Earth. Mnemonic: "Orbit = Light Switch"

Copernicus’ Key Improvement

Heliocentrism with circular orbits (retained epicycles for accuracy). Mnemonic: "Sun-Center + Circles"

Planetary Magnetic Field Generation

Dynamo effect: conducting fluid motion + rotation generates field. Mnemonic: "Spin Flow = Magnetic Glow"

Carbon Dioxide Sources and Sinks

Sources: volcanoes/respiration; sinks: weathering/photosynthesis. Mnemonic: "Vents In, Plants Out"

Lunar Eclipse Geometry and Phase

Earth between Sun/Moon → full Moon in Earth’s shadow. Mnemonic: "Full Moon Shadow Play"

Venus vs. Mars Atmospheres

Both CO₂-rich; Venus: thick/hot, Mars: thin/cold. Mnemonic: "Venus Sauna, Mars Freezer"

Volcanic Features on Venus

Shield volcanoes and pancake domes (viscous lava). Mnemonic: "Venus: Lava Pancakes"

Solar Eclipse Geometry and Phase

Moon between Sun/Earth → new Moon casts shadow on Earth. Mnemonic: "New Moon Blocks Sun"

Mars Rover Example

Curiosity (Gale Crater, habitability) and Perseverance (Jezero Crater, life signs). Mnemonic: "CG Seeks Life, PJ Hunts Life"

Evidence for Martian Water

Dry river valleys and seasonal briny flows (recurring slope lineae). Mnemonic: "Mars Rivers: Salty Shivers"

Jovian Planet Spots Formation

High-pressure storms at jet stream boundaries (e.g., Great Red Spot). Mnemonic: "Jet Stream Storms"

Saturn’s Muted Colors

Thick photochemical haze and slower reactions due to cold temperatures. Mnemonic: "Hazy & Lazy Colors"

Blue Atmospheres of Uranus and Neptune

Methane absorbs red light, scatters blue wavelengths. Mnemonic: "Methane = Blue Screen"

Convection and Jupiter’s Bands

Upwelling materials create colored cloud bands of varying composition. Mnemonic: "Rising Stuff = Stripes"

Io’s Volcanic Activity

Tidal heating from Jupiter’s gravity drives extreme volcanism. Mnemonic: "Jupiter’s Squeeze = Lava Ease"

Outer Moons with Liquid Water

Europa (Jupiter) and Enceladus (Saturn) have subsurface oceans. Mnemonic: "Euro-pa & Encel-adus: H₂O+"

Saturn’s Rings Composition and Size

Water ice particles (µm to m size); mass ≈ 0.1 Mimas. Mnemonic: "Icy Sparkles, Tiny Mass"

Unique Feature of Titan

Only moon with thick atmosphere and liquid methane lakes. Mnemonic: "Titan: Methane Earth"

Unusual Triton

Retrograde orbit (captured KBO) with nitrogen geysers. Mnemonic: "Backward Moon with Gas Jets"

Electromagnetic Spectrum Commonality and Differences

All light travels at c; gamma (short λ) to radio (long λ). Mnemonic: "Gary X-rays My Underwear, Visible In Red"

Hot Blackbody Spectrum

Peak wavelength shifts inversely with temperature (Wien’s Law). Mnemonic: "Hotter = Bluer Peak"

Information from Continuous Spectrum

Reveals temperature (peak λ) and luminosity (total energy). Mnemonic: "Peak = Heat, Area = Power"

Spectroscope with Cool Hydrogen Cloud

Dark lines from electron transitions in hydrogen atoms. Mnemonic: "Hydrogen’s Light Fingerprints"

Ionized Gas Emission Spectrum

Bright lines reveal elemental composition and gas conditions. Mnemonic: "Glowing Gas ID Card"

Nuclear Fusion Process

H → He at >10⁷ K via proton-proton chain/CNO cycle; releases energy. Mnemonic: "H Squeeze = He + Energy"

Sunspots and Prominences Link

Both tied to magnetic fields: sunspots (cool/dark), prominences (plasma loops). Mnemonic: "Magnetic Sun Pimples & Arches"

Sunspot Cycle Variation

~11-year activity cycle (min → max → min); affects space weather. Mnemonic: "Sun’s 11-Year Mood Swing"

Solar Wind Definition

Charged particles streaming from corona; shapes magnetospheres. Mnemonic: "Sun’s Breath Pushes Planets"

Layers of the Sun’s Atmosphere

Photosphere (visible), chromosphere (mid-layer), corona (hot outer). Mnemonic: "Photo = Face, Chromo = Coat, Corona = Crown"

Parallax Determination

Star’s apparent shift from opposite Earth orbit points → distance (1/angle). Mnemonic: "Shift Back = Distance Track"

Upper-Right HR Diagram Star Properties

Cool, luminous red giants/supergiants (large size). Mnemonic: "Cool Big Glowers"

Sun’s Size in Stellar Context

Average G-type main-sequence star; not a subgiant/giant. Mnemonic: "Sun: Medium Star"

Mass of Common Stars

Most are red dwarfs (0.1–0.5 M☉); low luminosity, long lives. Mnemonic: "Tiny Red Majority"

Emission Nebula Formation

UV radiation from hot stars ionizes gas → emission lines. Mnemonic: "Star Light, Gas Bright"

New Star Birth Indicators

Protostellar jets, bipolar outflows, and dust cocoons. Mnemonic: "Jets + Dust = Baby Star"

Importance of O Stars

Ionize nebulae and trigger star formation via UV/winds. Mnemonic: "O Stars: Cosmic Triggers"

Locations of Emission Nebulae

Star-forming regions in spiral arms/molecular clouds. Mnemonic: "Nebulae in Stellar Nurseries"

Trigger for Red Giant Evolution

Core H exhaustion → shell fusion → envelope expansion/cooling. Mnemonic: "H Gone → Star Bloats"

Stellar Death and Earth’s Life

Supernovae disperse heavy elements (C, O, Fe) for planets/life. Mnemonic: "Dead Stars, Living Planets"

Iron’s Role in High-Mass Stars

Fusion stops at iron → core collapse → supernova. Mnemonic: "Iron = Star Killer"

Definition of White Dwarf

Degenerate core remnant of low-mass stars; electron pressure-supported. Mnemonic: "Dead Star Cinder"

Planetary Nebula Formation

Star ejects envelope → ionized by core → glowing gas shell. Mnemonic: "Gas Shroud + UV Light"

Cause of Type I Supernova

White dwarf exceeds Chandrasekhar limit (1.4 M☉) → carbon detonation. Mnemonic: "Stolen Mass = Star Bomb"

Neutron Star Properties

~1.4–2 M☉ in 20 km radius; strong B-fields, rapid rotation. Mnemonic: "Tiny, Dense, Spinning Magnet"

Pulsar Explanation

Rotating neutron star with beamed radiation → observed pulses. Mnemonic: "Lighthouse in Space"

X-ray Burst Mechanism

Thermonuclear runaway on accreting neutron star surface. Mnemonic: "Stolen Fuel = X-ray Flash"

Gamma Ray Burst Locations

Cosmological distances; isotropic sky distribution. Mnemonic: "GRBs: Everywhere, Far Away"

Gamma Ray Burst Model

Core collapse of massive star → black hole → relativistic jets. Mnemonic: "Star Death → Jet Fireworks"

Black Hole Binary Conditions

Rapid orbital motion + X-ray emission + no visible companion. Mnemonic: "Invisible Dancer with X-ray Shoes"

Halo vs. Disk Differences

Halo: old stars, random orbits; Disk: young stars, gas, spiral arms. Mnemonic: "Halo: Grandpa’s Chaos; Disk: Youth Order"

Dark Matter Evidence

Flat rotation curves and gravitational lensing reveal unseen mass. Mnemonic: "Invisible Glue Holds Galaxies"

Supermassive Black Hole Indicators

Fast stellar orbits around Sagittarius A* (~4×10⁶ M☉); X-ray flares. Mnemonic: "Stars Zip, Black Hole Sits"

Definition of Globular Cluster

Dense, spherical groups of ancient stars in galactic halos. Mnemonic: "Star Fossils in Balls"

Cepheid Distance Measurement

Period → luminosity → distance (via brightness comparison). Mnemonic: "Pulse = Cosmic Yardstick"

Properties of the Galactic Disk

Gas, dust, spiral arms, young stars; higher metallicity than halo. Mnemonic: "Disk: Star-Making Factory"

Hubble’s Galaxy Types

Spirals, ellipticals, barred spirals, irregulars. Mnemonic: "Some Eat Berries, Irritably"

Spiral vs. Elliptical Differences

Spirals: gas-rich, star-forming; ellipticals: gas-poor, old stars. Mnemonic: "Spirals: Youthful & Active; Ellipticals: Retired & Calm"

Active Galaxy Common Traits

Luminous cores (SMBH accretion), multiwavelength jets, strong emission lines. Mnemonic: "Black Hole Powerhouse"

Hubble’s Law

v = H₀d: galaxies recede faster with distance → universe expands. Mnemonic: "Farther = Faster Flight"