final exam study guide

Electromagnetic spectrum order

Radio → Infrared → Visible → Ultraviolet → X-ray

Shorter wavelength means

Higher energy and bluer light

Longer wavelength means

Lower energy and redder light

Emit

Produce light

Absorb

Take in light

Transmit

Light passes through

Reflect/Scatter

Light bounces

Thermal emission rules

Hotter objects emit more energy and shorter wavelength with bluer light

Why stars are red or blue

Their color depends on temperature with blue stars hotter and red stars cooler

Why planets are red or blue

Their color depends on surface or atmospheric composition not temperature

Why auroras have different colors

Different gases emit different colors when energized such as oxygen (green or red) and nitrogen (blue or purple)

Which planets have thick atmospheres

Venus and Earth

Which planets have thin atmospheres

Mars and Mercury

Main atmospheric compositions

Earth is mostly nitrogen and oxygen while Venus and Mars are mostly carbon dioxide

How gas particles behave

They move randomly collide to create pressure and move faster at higher temperatures

What determines surface temperature

Distance from the Sun, albedo, and the strength of the greenhouse effect

Greenhouse effect

Greenhouse gases absorb infrared radiation and trap heat in the atmosphere

Is the greenhouse effect bad

It is necessary for life but too much causes extreme heating

Greenhouse gases vs non greenhouse gases

Carbon dioxide, water vapor, and methane trap heat while nitrogen and oxygen do not

Why mountains are cold

Lower pressure at high altitude causes air to expand and cool

Troposphere role

Weather occurs here and greenhouse gases regulate surface temperature

Stratosphere role

Ozone absorbs ultraviolet light protecting life

What happens without ozone

Harmful ultraviolet radiation reaches the surface and damages life

Magnetosphere

A magnetic field that protects a planet from solar wind and prevents atmospheric loss

Three sources of atmospheres

Outgassing, impacts, and evaporation

Four ways atmospheres are lost

Thermal escape, impact ejection, chemical reactions, and solar wind stripping

Earth atmosphere summary

Balanced greenhouse effect, liquid water, and active plate tectonics

Venus atmosphere summary

Thick carbon dioxide atmosphere with runaway greenhouse heating

Mars atmosphere summary

Thin atmosphere due to low gravity and lack of magnetic field

Importance of water on Earth

Drives weather, regulates temperature, and supports life

Importance of carbon dioxide

Controls temperature through the greenhouse effect

Importance of nitrogen

Provides a stable background gas

Importance of oxygen

Produced by life and supports respiration

Importance of ozone

Absorbs harmful ultraviolet radiation

Carbon dioxide cycle

Moves carbon between atmosphere oceans and rocks regulating climate

Runaway greenhouse effect

Positive feedback causes extreme heating like on Venus

Feedback mechanisms

Processes that amplify or reduce climate changes

Snowball Earth

A period when Earth was almost completely frozen

Jovian vs terrestrial planets

Jovian planets are large, gas rich, and low density while terrestrial planets are small, rocky, and dense

Why jovian planets have many moons

Their strong gravity captures objects and they formed with surrounding disks

Why jovian moons are active

Tidal heating and radioactive decay provide internal energy

Tidal heating

Gravitational stretching from varying forces generates heat inside moons

Conditions for tidal heating

A non circular orbit and orbital resonance

Io activity

Strong volcanism from tidal heating

Europa activity

Likely subsurface ocean due to tidal heating

Titan features

Thick atmosphere, methane lakes, and weather cycles

What rings are made of

Many small particles orbiting independently

How rings form structure

Shepherd moons and orbital resonances create gaps and edges

Origin of rings

Debris from broken moons or comets

Asteroids vs comets

Asteroids are rocky and inner solar system while comets are icy and outer solar system

Meteorite types

Metal, rocky, stony-metal, and primitive

Meteorite history

Form early, break apart, travel through space, and fall to Earth

Why comets have two tails

Solar wind creates ion tail and sunlight pressure creates dust tail

What happens to comets over time

They lose material and shrink with repeated orbits

Two groups of comets

Short period from Kuiper Belt and long period from Oort Cloud

Pluto characteristics

Similar to Kuiper Belt objects but has atmosphere and moons

Role of small bodies on Earth

Delivered water, caused extinctions, and shaped geology

Why meteor showers occur

Earth passes through debris left by comets

Impact sizes and effects

Small impacts cause local damage, medium impacts cause global effects, large impacts cause mass extinctions

Role of jovian planets in impacts

They deflect or redirect objects reducing impacts on Earth

Why exoplanets are hard to detect

They are faint and hidden by their stars brightness

Doppler method

Measures star wobble to determine planet mass

Transit method

Measures brightness dips to determine planet size

Most successful detection method

Transit method

Why orbit orientation matters

Edge on orbits are easier to detect than face on

What exoplanets revealed

Many systems differ from ours and hot Jupiters are common

Are Earth like planets common

Likely common but still being studied

Requirements for life

Liquid water, energy source, and chemical building blocks

What Earth suggests about life

Life can arise quickly when conditions are right

Best places to search for life

Mars, Europa, and Enceladus

Habitable zone

Region where liquid water can exist on a planet’s surface

Origin of water

Hydrogen came from the Big Bang, oxygen from stars, and water delivered by impacts

Why Earth is habitable

Right distance, moderate greenhouse effect, liquid water, magnetic field, and plate tectonics

How atmosphere evolved

Changed over time through sources loss processes and life

Role of mass extinctions

They reshaped evolution and allowed new life forms to develop

Cost of space exploration

About ten dollars per person

Water and geology interaction

Water drives erosion and plate tectonics recycle it

Water and atmosphere interaction

Atmosphere controls water phases and cycles it through weather

Atmosphere and life interaction

Atmosphere provides gases and protection needed for life

Life and atmosphere interaction

Life changes atmospheric composition especially oxygen levels

Geology and stable climate interaction

Plate tectonics regulate carbon dioxide to stabilize climate

Water and stable climate interaction

Water stores and redistributes heat reducing extremes

Water and life interaction

Liquid water enables essential chemical reactions for life

Stable climate and life interaction

Stable conditions allow life to survive and evolve