Astronomy Exam 1

What is a planet?

Celestial body that orbits a star

What is a star?

Celestial body large enough to sustain hydrogen fusion

What is a star system?

Collection of stars and planets gravitationally bound

What is our star system called?

Solar system

What determines star temperature?

Star size, which in turn determines color

What color is the sun?

White from space, yellow to us, emits mostly green

What is a galaxy?

Collection of star systems

What is our galaxy called?

Milky Way

How big is the Milky Way across?

100,000 light years

What is a group?

Collection of galaxies

What is our group?

Local Group

What is a cluster?

Larger collection of galaxies

Do galaxies have to be in a cluster?

No—Local Group is not in one

What is a supercluster?

Collection of groups and clusters

What is our supercluster?

Virgo Supercluster, which is part of Laniakea

What is a supercluster complex?

Filaments, threadlike features

What is the universe made of?

73% Hydrogen
25% Helium
2% metals

What decides how much metal a star has?

Its age—the younger the star, the more metals

What is one astronomical unit?

The average distance from the Earth to the Sun, or 150 million km

How far is Neptune from the Sun?

About 30 AU

What is a light-year?

The distance light travels in one year

What are the three fossil fuels?

Coal, natural gas, and oil

What are the 4 advantages to fossil fuels?

High energy density
Infrastructure is already in place
Easy to find and transport
Reliability

What are the 5 disadvantages to fossil fuels?

Non-renewable
Accidents are dangerous and harmful
Prices and supply are susceptible to weather and world events (like politics)
Release greenhouse gases and pollute
Dangerous to extract from the Earth

What is the electromagnetic spectrum, smallest wave to largest wave?

Gamma rays (most pressed together, most energetic)
X-rays
Ultraviolet
Visible light
Infrared
Microwaves
Radio waves (least pressed together, least energetic)

What is the particle of light?

Photons

Light is both a particle and a wave

True

Different types of light move at different speeds

False; they move at the constant speed of light, they just have different wavelengths

What is the atmosphere?

The layer of gas around a planet

What are the 4 layers of the atmosphere, lowest to highest?

Troposphere
Stratosphere
Thermosphere
Exosphere

What is the troposphere?

Lowest level of the atmosphere, where visible light makes it to the surface

What is the stratosphere?

Second level of atmosphere, where UV is absorbed, has ozone layer

What is the thermosphere?

Third level of atmosphere, where x-rays are absorbed

What is the exosphere?

Outer layer of atmosphere

What is the temperature in our atmosphere?

It gets colder until the stratosphere, then it gets warmer, then colder nearing the thermosphere, then rises exponentially closer to space

Where is the ozone layer?

Stratosphere

What does the ozone layer do?

It absorbs UV light. Light hits an O2 molecule, splitting it into individual atoms, which then bond with more O2 to make O3 (ozone).

What gases make up our atmosphere?

78% Nitrogen
21% Oxygen
1% all other gases

What percentage of sunlight makes it to the surface? How much is absorbed by the atmosphere? How much is albedo?

50% to the surface
20% absorbed by the atmosphere
30% albedo

What is albedo?

Amount of light reflected off of a body

What is Earth's albedo?

.3 or 30%

How does the greenhouse effect work?

Greenhouse gases absorb infrared light and re-emit it in all directions—some makes it back to the surface, reheating it

The greenhouse effect is bad

False; it is good in moderation, but too much is harmful

What are the 6 greenhouse gases?

Carbon Dioxide
Methane
Nitrous Oxide
Water Vapor
Ozone
Fluorinated Gases

Where do the greenhouse gases reside?

Troposphere

What is residence time?

The time it takes to remove a molecule from the atmosphere

What is the most abundant greenhouse gas?

Water vapor, making up 50% of the greenhouse effect

What is water vapor's residence time?

9 days

What are fluorinated gases?

Gases that have flourine

What is the most effective greenhouse gas?

Fluorinated gases (sulfur hexafluoride is the most effective of these)

Where are fluorinated gases used?

Aerosols, fire extinguishers, refrigerators, and more

What are fluorinated gases' residence time?

800-3000 years

What are CFCs?

Chlorofluorocarbons, which were banned in 1989 because they damage the ozone layer

How do CFCs damage the ozone layer?

They take the oxygen atom away from O3, allowing it to bond with chlorine, then the oxygen atom will bond with another oxygen atom, making O2

Where is nitrous oxide used?

Whipped cream, laughing gas

What is nitrous oxide's residence time?

120 years

How much more powerful is nitrous oxide compared to carbon dioxide?

300x more powerful

Where is methane used?

Farming

What is methane's residence time?

12 years

How much more powerful is methane than carbon dioxide?

30x more powerful

Where is good ozone?

Stratosphere, in the ozone layer

Where is the bad ozone?

Troposphere, ground-level

What is ozone's residence time?

Weeks

What is the weakest greenhouse gas?

Carbon dioxide

What is carbon dioxide/s residence time?

Unknown, due to the carbon cycle

What percentage of emissions are carbon dioxide?

82%

What is the most dangerous greenhouse gas?

Carbon dioxide

What are the six types of renewable energy?

Solar
Hydroelectric
Tidal
Geothermal
Biomass
Wind

What are the five advantages of renewable energy?

Cheap fuel source
No carbon emissions (with exceptions during manufacturing)
Renewable
Does not depend on world events or foreign governments
Government subsidizes it

What are the eight disadvantages of renewable energy?

Low energy density
High start-up costs
Intermittent (it's not constantly windy)
Storage issues
Location
Large footprint
Missing infrastructure
Carbon emissions during manufacturing

What is concentrated solar power?

Sunlight is reflected from mirrors onto a source

What is a solar power tower?

Mirrors reflect onto a tower, melting salt, which mixes with water to make steam, turning a turbine

What are the four disadvantages to solar power towers?

Uses lots of water
Kills birds due to temperature
Lots of moving parts to replace
Large footprint

What are the three advantages to solar power towers?

High thermal efficiency
Easy maintenance (heliostats are easy to replace)
Heliostats track sun's movement

What is a parabolic dish?

A giant, curved mirror that reflects sunlight onto a single point

What are the three disadvantages to parabolic dishes?

Does not track sun
Curved mirrors are fragile/expensive
It is a huge structure and complex to build

What are the three advantages to parabolic dishes?

No moving parts
More thermal efficiency
Small footprint

What is a parabolic trough?

A trough of curved mirrors reflecting sunlight onto a receiver tube

What are the 3 disadvantages to parabolic troughs?

Curved mirrors are fragile/expensive
Uses oil at focal point
Only tracks sun up/down

What are the two advantages to parabolic troughs?

More thermal efficiency
Tracks sun

What are photovoltaic cells?

Solar panels

How do solar panels work?

Light hits the semi conductors, knocking the electrons off, which then move to make a current

What is passive solar heating?

Maximizing/minimizing the sun with building design

What are the issues with solar energy?

The seasons cause differences in amount of sunlight
Lines of latitude—sun does not go high enough in the sky to be most efficient

What is an analemma?

Diagram of the sun's position from the exact same position at the exact same time every day of the year. It makes a figure eight

What is the zenith and where does it occur?

When the sun is directly overhead, occurs between Lat ±24. It happens twice per year at the equator (on the equinoxes) and once per year at the Tropic of Cancer/Capricorn. On the December solstice, it is at the Tropic of Capricorn (-24), while on the June solstice, it is at the Tropic of Cancer (+24)

What is midnight sun?

When the sun shines all night in the arctic circle

What is polar night?

When the sun does not rise all day in the arctic circle

What is perihelion?

The point in orbit closest to the sun, in December

What is aphelion?

The point furthest from the sun in orbit, in June

What causes the seasons?

Earth's axis, which affects which part of the planet is closest to the sun

What do the lines of latitude affect?

Solar radiation and the amount of sunlight

When are solar panels most efficient?

When the sun is perpendicular to the panel

How does wind energy work?

Wind turns a turbine

How is wind created?

The sun heats the atmosphere unevenly, which creates pressure differences, in turn making wind

What are the six disadvantages of wind energy?

Expensive to start
Location dependent
Kills birds
Large land area for wind farms (they must be spread out due to air turbulence)
Moving parts can break
Radar interference

What are the three advantages of wind energy?

Small footprint per turbine
Versatile
No carbon output

Which state leads in wind energy?

Texas

Can you put wind turbines in the ocean?

Yes, but maintenance is hard and they interrupt shipping lanes

What determines the amount of power from a wind turbine?

Sweep area or blade length, as well as wind speed