Earth and the Solar System Flashcards
What is the Earth System?
a dynamic body with many separate, interacting parts/spheres
What are the characteristics of the Geosphere?
solid rock and surface features
6400km to the centre
Lithosphere about 100km thick
What percentage of the surface does the hydrosphere occupy and what is its breakdown?
71% of surface
97% ocean, 3% freshwater
What are the characteristics of the atmosphere?
thin, gaseous envelope, 90% within 16 km of surface
integral to planet (weather, climate) and biosphere (breathing, UV protection, heat)
What are the characteristics of the Biosphere?
all life, contained near surface
organisms alter the makeup and nature of all spheres
what are some examples of natural resources in the earth system?
metals
water
food
materials
What are some examples of hazards in the earth system?
earthquakes
eruptions
flooding
forest fires
What are some examples of matter moving?
plate tectonic system
hydrological, atmospheric cycles
rock cycle, carbon cycle
What are some examples of energy flows?
external
internal
What are life webs?
network of relationships
connect all organisms with matter cycles and energy flows
Which is the thickest of the earths spheres?
Geosphere
around 6400km thick
What is the biggest source of the earth’s energy?
sun solar energy (shortwave radiation) contributes 99.985% of earths total energy budget
Where is solar energy more concentrated?
in the equatorial regions
Solar energy
powers processes acting on earths surface which are crucial for life eg photosynthesis
affects atmospheric circulation, ocean circulation, hydrologic cycle
the net effect of solar energy evens out surface topography
Where does earths internal energy come from?
very hot core
radioactivity in the mantle
What is nucleosynthesis?
the formation of elements by various means
eg. big bang, large stars, supernovae, cosmic rays, small stars
What are the steps from gas to planet?
gas dust grains rocks asteroids planets
What are condensing and accretion?
pulling together and adding together
What is the evidence for condensing and accretion?
Meteorites: rocks from space, record condensation / accretion
Asteroid belt: ‘leftovers’ between Mars and Jupiter
Impacts & craters on Moon
Study of other star systems
Earth was initially hot. Where was it hottest? Why?
compressional heating under gravity -> hottest at centre
What heated earth more?
Accretion – shock heating
Radioactive decay – short lived isotopes
What did high earth temperatures lead to?
melting and differentiation
What are chondrites?
the most primitive meteorites
What is the composition of a chondrite? What does it reflect?
same relative abundance of elements as the Sun
reflects ‘starting’ materials for planets
this means it was never part of a body large enough to undergo melting & differentiation
Early earth was a …… ocean.
magma
What is a good way to visualise the scale of the solar system?
If the Sun were an orange:
earth would be a grain of sand 9 metres away
Jupiter would be a pea 60 metres away
the nearest star would be 1600km away
What are the terrestrial (rocky) planets?
Mercury, Venus, Earth, Mars Closest to the sun (inner planets) Small High mean density (4-5.5 g/cm³) rock and metallic elements
What are the jovian (gassy) planets
Jupiter and Saturn (gas giants) Uranus and Neptune (ice giants) Outer planets Large Low density (0.7-1.7 g/cm³) gaseous (He, H₂)
Where is the frost line?
between the terrestrial and jovian planets
What are Venus’ characteristics?
Rolling topography Active volcanism Cloudy, thick CO2-rich atmosphere High surface temp (450 °C) No water (runaway greenhouse effect) Analogue of early/future Earth?
What are Mars’ characteristics?
Cold, windy Tremendous topography Volcanism Small core Ice caps (water & CO2)- Liquid water? Life? (maybe)
What are Earth’s characteristics?
Water in 3 forms Land, sea Rivers, lakes Continents Topography Temp gradient Life, including Humans
Why is earth unique?
has a water cycle
Why is Earth so different?
Just right distance from Sun to have water as solid, liquid, and gas Water cycle (closed system) - Results in a young regenerated surface and Enables planetary-scale life to evolve (earth-atmosphere exchange of elements) Internal heat– long-term (ongoing) radioactive decay of elements Convection (movement) in solid rocky interior (over long periods acts as a fluid)
