astronomy

nebular theory

the solar system formed ~4.6 billion years ago from a rotating cloud of gas and dust that collapsed under gravity

condensation

gaseous elements and compounds cool and turn into tiny solid particles or liquid droplets

frost line

the distance from the young Sun where temperatures were low enough for water, ammonia, and methane to freeze into ice

accretion

small particles collide and stick together, gradually forming larger bodies like planets

planetesimal

small solid object formed early in the solar system, a building block for planets

asteroid

small rocky object orbiting the Sun, mostly between Mars and Jupiter

comet

icy body that orbits the Sun and forms a coma and tail when heated

protoplanet

large, developing planetary body formed by merging planetesimals

heavy bombardment

early period when planets were hit frequently by many planetesimals

gas capture

when a forming planet accumulates surrounding hydrogen and helium gas from the solar nebula

impact cratering

circular depressions formed on a surface when meteoroids collide with it

tectonics

movement and deformation of a planet’s outer layer, including plate motion and crust recycling

erosion

process of wearing away and transporting surface material via wind, water, ice, or gravity

volcanism

eruption of molten rock and gases from a planet’s interior to its surface

outgassing

release of gases from a planet’s interior into its atmosphere, often through volcanoes

greenhouse effect

warming of a planet because atmospheric gases trap infrared radiation

carbonate rock

rock made mostly of carbonate minerals, often storing carbon dioxide over long periods

carbon dioxide cycle

the movement of CO2 between a planet’s atmosphere, surface, and interior via volcanism, weathering, and subduction

average density

total mass divided by volume, helps determine composition and internal structure

oblateness

flattening of a rotating object at its poles due to rotation, causing equatorial bulge

radiometric dating

determining age by measuring radioactive isotopes and their decay products

half-life

time required for half of a radioactive substance to decay

photon

a discrete packet of electromagnetic energy

wavelength

distance between successive peaks or troughs of a wave

frequency

number of wave cycles per second

speed of light

constant speed of light in vacuum, ~3 × 10^8 m/s

spectrum

range of electromagnetic radiation separated by wavelength or frequency

spectral lines

specific wavelengths absorbed or emitted by atoms or molecules, appearing as lines

temperature

measure of average kinetic energy of particles

blackbody

ideal object that absorbs all incoming radiation and emits energy based on temperature

thermal radiation

electromagnetic radiation emitted by an object due to its temperature

rotation importance

rotation flattened the gas cloud into a disk, allowing material to orbit in the same direction and collide, forming planets

asteroids and comets role

they were leftover planetesimals, building planets and delivering water and gases via impacts

jovian vs terrestrial formation

jovian planets formed beyond the frost line with ices and large cores that captured gas; terrestrial planets formed closer in where it was too hot for ices

terrestrial planet differences

mercury: small, thin/no atmosphere, extreme temperatures; venus: Earth-sized, thick CO2 atmosphere, extreme greenhouse; earth: moderate atmosphere, liquid water; mars: smaller, thin atmosphere, cold and dry

volcano meaning

volcanoes reveal internal heat and molten material inside a planet

volcano distribution

venus and earth: many; mars: fewer but very large; mercury: few, mostly ancient

planet size and heat

smaller planets lose internal heat faster due to higher surface-area-to-volume ratio

crater differences

mercury and mars: many craters; venus: fewer (resurfacing); earth: fewest (erosion/tectonics)

atmosphere factors

distance: controls temperature; volcanoes: supply gases; liquid water: removes CO2 via weathering

gas escape

ease of gas escape depends on planet’s gravity and temperature; low gravity and high temp make escape easier

terrestrial vs jovian

terrestrial: small, rocky, dense; jovian: large, gaseous, low density, many moons

jovian interiors

density shows composition, oblateness shows rapid rotation and fluid interior

light relationships

wavelength and frequency are inversely related; energy increases with frequency, decreases with wavelength

most energetic light

UV, X-rays, gamma rays have highest energy and are most harmful

spectrum info

spectral lines reveal composition, temperature, motion (Doppler effect), and other physical conditions

thermal radiation vs size

if temperature is constant, total radiation increases with surface area; radiation per unit area stays the same

red filter effect

blocks all colors except red, only red passes through

filter model

light behaves like particles of different types; filters stop some, allow others

prism after red filter

only red light is spread out and seen

white light meaning

white light is a mixture of many colors

blue clothes under yellow light

appear black because yellow light has no blue to reflect

red clothes under yellow light

appear black because yellow light has no red to reflect

highest frequency wave

dark purple light has highest frequency in visible spectrum

red light properties

longest wavelength, lowest energy among visible light

number line quantity

represents increasing wavelength

highest energy EM

X-rays and gamma rays

missing colors spectrum

removing green/orange leaves gaps in spectrum

EM comparisons

radio: long wavelength, low frequency; X-ray: high frequency, high energy; infrared: low energy

light bulb heating

temperature increase → dark → red → bright white

making light whiter

add blue light to shift color toward white

color brightness increase

red and green intensities increase as filament heats up

last visible color

violet appears last as temperature rises

earth emission

mostly infrared radiation

infrared sources

Earth and humans emit primarily infrared light

hottest star

shortest peak wavelength = highest temperature

blue liquid observation

reflects mostly blue light, absorbs other colors

blue liquid spectrum

removes red, orange, yellow from light passing through

neptune color

appears blue because its atmosphere absorbs red light and reflects blue

planet direction probability

probability all planets orbit same direction randomly < 1%

planet motion

most planets rotate same way; all orbit Sun same way

sun vs earth size

earth is extremely small compared to Sun

planet mass vs sun

total mass of planets << Sun

chair spin arms in

pulling arms inward increases spin rate (conservation of angular momentum)

chair spin arms up/down

moving arms along spin axis does not change rotation noticeably

no rotation cloud

no disk forms, planets do not orbit

inner solar material

only metals/rock condense near Sun

material distribution

rock forms near Sun; rock+ice farther away

water location

water: gas near Sun, ice beyond frost line

terrestrial location

terrestrial planets formed in hotter inner regions

comet vs asteroid

comets: icy, distant; asteroids: rocky, closer

condensation meaning

gas turns into solid or liquid

cold formation planets

jupiter and saturn formed beyond frost line

jupiter at mars

could not form in Mars’ orbit (too hot)

collision frequency

collisions decrease as particles grow larger

solar cloud composition

mostly hydrogen/helium, small amounts of heavier elements

nebular theory limit

does not explain why exactly 4 terrestrial and 4 jovian planets

earth volcano location

most around Pacific Ocean edges

crater ranking

mercury > mars > venus > earth

volcano ranking

venus > earth > mars > mercury

mars craters

medium number, mostly on one side

craters vs size

larger planets tend to have fewer craters due to geologic activity

moon craters timing

most craters formed early (heavy bombardment)

volcanoes vs size

larger planets retain heat, so more volcanoes

exoplanet prediction

slightly smaller than Venus: likely has volcanoes, may or may not be active

rock dating age

4% → 1% after 2 half-lives; age = 160 million years

radioactive decay time

64 → 8 atoms = 3 half-lives = 30 seconds

most craters surface

small planet far from Sun has most craters

large far planet surface

many volcanoes, few craters, some erosion

light vs gas

UV absorbed by ozone, visible passes through water, infrared absorbed by CO2