ESS 101 EXAM 1 QUESTION
ANSWERSt
nebular-hypothesis---ans-✔✔1.-supernova-and-formation-of-primordial-dust-cloud-
2.-condensation-of-primordial-dust-forms-disk-shaped-nebular-cloud-rotating-counter-
clockwise.-
3.-proto-sun-and-planets-begin-to-form-
4.-accretion-of-planetesimals-and-differentiation-of-planets-and-moons-(4-6-billion-years-
ago).-
5.-existing-solar-system-takes-shape.
Evidence-of-nebular-hypotheses---ans-✔✔1.-Planets-and-moons-revolve-in-a-counter-
clockwise-direction-(not-random)-
2.-almost-all-planets-and-moons-rotate-on-their-axis-in-a-counter-clockwise-direction.-
3.-planetary-orbits-are-aligned-along-the-suns-equatorial-plane-(not-randomly-organized)-
4.-observations-from-Hubble-telescope-and-radio-astronomy-indicate-that-other-planetary-
systems-are-forming-from-condensed-nebular-dust.
Terrestrial-Planets---ans-✔✔Close-to-the-sun,-dense,-small/rocky,-silicate-minerals,-
metallic-cores-
Twelve-earths-would-fit-across-the-diameter-of-Jupiter.
Jovian-Planets---ans-✔✔Far-from-the-sun,-low-density,-large,-gaseous-(hydrogen,-
methane)
Why-does-the-earth-and-terrestrial-planets-have-so-little-molecular-hydrogen-comprising-
their-respective-atmosphere,-yet-the-primordial-dust-cloud-was-mostly-comprised-of-
hydrogen-gas?---ans-✔✔Hydrogen-gas-and-helium-gas-escapes-to-space-when-put-in-
our-atmosphere.-
Jupiter,-saturn,-and-neptune-maintain-molecular-hydrogen-gas-in-the-atmosphere-
because-they-have-high-density.
Differentiated-Earth---ans-✔✔1.-Iron-Nickel-Core-(outer-core-liquid)-
(inner-core-solid)-
2.-Fe-Mg-silicate-mantle-
,3.-Fe-Mg-Al-Silicate-Crust-(Ocean-and-Continental)
4.-Oceans-
5.-atmosphere
How-is-the-earth-compositionally-zoned?---ans-✔✔Along-a-density-gradient
How-did-the-earth-become-compositionally-zoned?---ans-✔✔1.-Accretion-of-
planetesimals-
2.-initial-heating-due-to-kinetic-energy-of-colliding-planetesimals-and-compressional-
heating.-
3.-additional-heating-from-radioactive-decay.-
4.-iron-catastrophe:-melting-temp-of-iron-reached-and-dense-iron-nickel-sink-to-core-and-
lighter-materials-are-displaced-outwards-(including-silicate-rock-of-mantle-and-crust,-
ocean-waters-and-atmospheric-gases)-
5.-earth-becomes-compositionally-zoned-based-on-density-(densest-iron-nickel-in-core-
least-dense-materials-comprise-the-atmosphere)-500-mil-yrs-after-the-initial-accretion-
process.-
6.-convective-overturn-in-asthenosphere,-mantle-and-outer-core-still-occur-today.
Why-did-the-earth-heat-up-and-then-rapidly-cool-during-the-differentiation-process?---ans-
✔✔When-earth-was-solid-heat-gain-was-greater-than-the-heat-lost-to-space.-This-means-
that-the-internal-temperature-rises-until-it-exceeded-the-melting-temp-of-oxygen-and-
nitrogen-until-exceeded-iron-nickel-catastrophe.-Earth-is-completely-molten-and-then-
compositionally-zoned.-
When-earth-was-liquid--convection-hot-gas-rises-,-after-it-became-molten,-the-earth-
rapidly-cooled-off-and-solidified.
Why-does-earth-possess-little-evidence-of-its-early-accretion-history?---ans-✔✔Because-
of-weathering,-plate-tectonics,-moon-has-no-atmosphere-and-biosphere.
Emissions-from-degassing-of-the-earth-during-its-differentiation.---ans-✔✔h2o,-co2,-h2,-
he,-n2
Where-did-molecular-H-and-He-escape-to?---ans-✔✔space
When-did-oxygenation-of-the-atmosphere-occur?---ans-✔✔later-following-evolution-of-
marine-algae-and-plants-that-use-photosynthesis-to-convert-co2-to-o2-as-a-part-of-their-life-
processes.
What-layers-of-the-earth-can-be-directly-observed?---ans-✔✔crust-and-uppermost-mantle.
Evidence-of-initial-composition-of-the-solid-earth-based-on-meteorite-studies.-There-are-
two-major-classes-of-meteorites-that-dominate-collected-samples.-Carbon-based-
meteorites-are-much-rarer,-but-indicate-that-the-prescursor-of-life-was-present-early-on.---
ans-✔✔1.-Metallic-meteorites-(iron-nickel-density-9.0-10-gm/cm3)-
2.-chondritic-meteorites:-Fe-Mg-silicate,-rocky,-density-is-3.0-3.3)-
, 3.-carbonaceous-chondrites-(rare)
What-is-earths-average-density?---ans-✔✔5.5-g/cm3
How-can-average-density-of-earth-be-inferred?---ans-✔✔Based-on-gravitational-
properties-and-its-effect-on-known-masses-such-as-orbiting-satellites.
Density-of-earths-crust?---ans-✔✔2.6-3-g/cm3
density-of-uppermost-mantle?---ans-✔✔3.0-3.3-g/cm3
Based-on-the-density-information,-what-can-you-infer-about-the-density-of-the-lower-
mantle-and-the-earths-core?---ans-✔✔Density-must-be-higher-than-the-average.
What-does-the-presence-of-the-Earth's-magnetic-field-provide-evidence-for?---ans-
✔✔Earth-is-likely-to-possess-a-metallic-core-and-that-a-component-of-this-core-must-be-
liquid-and-convecting-around-the-solid-metallic-portion-of-the-core.
Seismic-waves---ans-✔✔s-and-p-waves
P-waves---ans-✔✔Compression-waves,-velocity:-6-7-km/sec-within-lithosphere,-
propagate-through-all-phases-of-matter.
S-waves---ans-✔✔Shear-waves,-3-4-km/sec,-only-propagate-through-solid-phases-of-
matter,-not-liquids-or-gases,-require-rigid-substance-(solid)-to-propagate.
Seismic-waves-refract-because---ans-✔✔because-of-velocity-changes-related-to-density-
changes-within-the-earth.-seismic-wave-accelerate-with-increasing-density.
P-wave-shadow-zone---ans-✔✔bagel-shaped,-exist-between-105-140-degrees-from-the-
epicenter-due-to-refraction-at-outer-core-mantle-boundary.-
no-p-or-s-waves.
s-wave-shadow-zone---ans-✔✔only-one-large-shadow-zone-at-an-angle-greater-than-105-
degrees-of-the-epicenter.-due-to-refraction-at-outer-core-mantle-boundary-and-because-s-
waves-are-absorbed-by-the-liquid-outer-core.
When-does-seismic-wave-velocity-decrease?---ans-✔✔at-depth-of-100-350-km-and-at-the-
mantle-core-boundary.-(low-velocity-zone)
When-are-s-waves-absorbed?---ans-✔✔only-at-the-mantle-core-boundary.
What-does-the-s-wave-being-absorbed-only-at-the-mantle-core-boundary-tell-you-about-
the-physical-property-of-the-upper-mantle?---ans-✔✔It-is-partially-melted.
lithosphere---ans-✔✔continental,-ocean-crust,-and-uppermost-solid-mantle
ANSWERSt
nebular-hypothesis---ans-✔✔1.-supernova-and-formation-of-primordial-dust-cloud-
2.-condensation-of-primordial-dust-forms-disk-shaped-nebular-cloud-rotating-counter-
clockwise.-
3.-proto-sun-and-planets-begin-to-form-
4.-accretion-of-planetesimals-and-differentiation-of-planets-and-moons-(4-6-billion-years-
ago).-
5.-existing-solar-system-takes-shape.
Evidence-of-nebular-hypotheses---ans-✔✔1.-Planets-and-moons-revolve-in-a-counter-
clockwise-direction-(not-random)-
2.-almost-all-planets-and-moons-rotate-on-their-axis-in-a-counter-clockwise-direction.-
3.-planetary-orbits-are-aligned-along-the-suns-equatorial-plane-(not-randomly-organized)-
4.-observations-from-Hubble-telescope-and-radio-astronomy-indicate-that-other-planetary-
systems-are-forming-from-condensed-nebular-dust.
Terrestrial-Planets---ans-✔✔Close-to-the-sun,-dense,-small/rocky,-silicate-minerals,-
metallic-cores-
Twelve-earths-would-fit-across-the-diameter-of-Jupiter.
Jovian-Planets---ans-✔✔Far-from-the-sun,-low-density,-large,-gaseous-(hydrogen,-
methane)
Why-does-the-earth-and-terrestrial-planets-have-so-little-molecular-hydrogen-comprising-
their-respective-atmosphere,-yet-the-primordial-dust-cloud-was-mostly-comprised-of-
hydrogen-gas?---ans-✔✔Hydrogen-gas-and-helium-gas-escapes-to-space-when-put-in-
our-atmosphere.-
Jupiter,-saturn,-and-neptune-maintain-molecular-hydrogen-gas-in-the-atmosphere-
because-they-have-high-density.
Differentiated-Earth---ans-✔✔1.-Iron-Nickel-Core-(outer-core-liquid)-
(inner-core-solid)-
2.-Fe-Mg-silicate-mantle-
,3.-Fe-Mg-Al-Silicate-Crust-(Ocean-and-Continental)
4.-Oceans-
5.-atmosphere
How-is-the-earth-compositionally-zoned?---ans-✔✔Along-a-density-gradient
How-did-the-earth-become-compositionally-zoned?---ans-✔✔1.-Accretion-of-
planetesimals-
2.-initial-heating-due-to-kinetic-energy-of-colliding-planetesimals-and-compressional-
heating.-
3.-additional-heating-from-radioactive-decay.-
4.-iron-catastrophe:-melting-temp-of-iron-reached-and-dense-iron-nickel-sink-to-core-and-
lighter-materials-are-displaced-outwards-(including-silicate-rock-of-mantle-and-crust,-
ocean-waters-and-atmospheric-gases)-
5.-earth-becomes-compositionally-zoned-based-on-density-(densest-iron-nickel-in-core-
least-dense-materials-comprise-the-atmosphere)-500-mil-yrs-after-the-initial-accretion-
process.-
6.-convective-overturn-in-asthenosphere,-mantle-and-outer-core-still-occur-today.
Why-did-the-earth-heat-up-and-then-rapidly-cool-during-the-differentiation-process?---ans-
✔✔When-earth-was-solid-heat-gain-was-greater-than-the-heat-lost-to-space.-This-means-
that-the-internal-temperature-rises-until-it-exceeded-the-melting-temp-of-oxygen-and-
nitrogen-until-exceeded-iron-nickel-catastrophe.-Earth-is-completely-molten-and-then-
compositionally-zoned.-
When-earth-was-liquid--convection-hot-gas-rises-,-after-it-became-molten,-the-earth-
rapidly-cooled-off-and-solidified.
Why-does-earth-possess-little-evidence-of-its-early-accretion-history?---ans-✔✔Because-
of-weathering,-plate-tectonics,-moon-has-no-atmosphere-and-biosphere.
Emissions-from-degassing-of-the-earth-during-its-differentiation.---ans-✔✔h2o,-co2,-h2,-
he,-n2
Where-did-molecular-H-and-He-escape-to?---ans-✔✔space
When-did-oxygenation-of-the-atmosphere-occur?---ans-✔✔later-following-evolution-of-
marine-algae-and-plants-that-use-photosynthesis-to-convert-co2-to-o2-as-a-part-of-their-life-
processes.
What-layers-of-the-earth-can-be-directly-observed?---ans-✔✔crust-and-uppermost-mantle.
Evidence-of-initial-composition-of-the-solid-earth-based-on-meteorite-studies.-There-are-
two-major-classes-of-meteorites-that-dominate-collected-samples.-Carbon-based-
meteorites-are-much-rarer,-but-indicate-that-the-prescursor-of-life-was-present-early-on.---
ans-✔✔1.-Metallic-meteorites-(iron-nickel-density-9.0-10-gm/cm3)-
2.-chondritic-meteorites:-Fe-Mg-silicate,-rocky,-density-is-3.0-3.3)-
, 3.-carbonaceous-chondrites-(rare)
What-is-earths-average-density?---ans-✔✔5.5-g/cm3
How-can-average-density-of-earth-be-inferred?---ans-✔✔Based-on-gravitational-
properties-and-its-effect-on-known-masses-such-as-orbiting-satellites.
Density-of-earths-crust?---ans-✔✔2.6-3-g/cm3
density-of-uppermost-mantle?---ans-✔✔3.0-3.3-g/cm3
Based-on-the-density-information,-what-can-you-infer-about-the-density-of-the-lower-
mantle-and-the-earths-core?---ans-✔✔Density-must-be-higher-than-the-average.
What-does-the-presence-of-the-Earth's-magnetic-field-provide-evidence-for?---ans-
✔✔Earth-is-likely-to-possess-a-metallic-core-and-that-a-component-of-this-core-must-be-
liquid-and-convecting-around-the-solid-metallic-portion-of-the-core.
Seismic-waves---ans-✔✔s-and-p-waves
P-waves---ans-✔✔Compression-waves,-velocity:-6-7-km/sec-within-lithosphere,-
propagate-through-all-phases-of-matter.
S-waves---ans-✔✔Shear-waves,-3-4-km/sec,-only-propagate-through-solid-phases-of-
matter,-not-liquids-or-gases,-require-rigid-substance-(solid)-to-propagate.
Seismic-waves-refract-because---ans-✔✔because-of-velocity-changes-related-to-density-
changes-within-the-earth.-seismic-wave-accelerate-with-increasing-density.
P-wave-shadow-zone---ans-✔✔bagel-shaped,-exist-between-105-140-degrees-from-the-
epicenter-due-to-refraction-at-outer-core-mantle-boundary.-
no-p-or-s-waves.
s-wave-shadow-zone---ans-✔✔only-one-large-shadow-zone-at-an-angle-greater-than-105-
degrees-of-the-epicenter.-due-to-refraction-at-outer-core-mantle-boundary-and-because-s-
waves-are-absorbed-by-the-liquid-outer-core.
When-does-seismic-wave-velocity-decrease?---ans-✔✔at-depth-of-100-350-km-and-at-the-
mantle-core-boundary.-(low-velocity-zone)
When-are-s-waves-absorbed?---ans-✔✔only-at-the-mantle-core-boundary.
What-does-the-s-wave-being-absorbed-only-at-the-mantle-core-boundary-tell-you-about-
the-physical-property-of-the-upper-mantle?---ans-✔✔It-is-partially-melted.
lithosphere---ans-✔✔continental,-ocean-crust,-and-uppermost-solid-mantle
