Origins of the Solar System and the Earth's Crust/Interior Flashcards
Describe how the objects in our solar system are identified, explored, and characterized
Identified: terrestrial planets, gas giants, TNO (trans-Neptunian object)
Explored: Uranus and Neptune through a telescope, while others were known by the ancients
Characterized:
- terrestrial: Small worlds, rock & metal, solid surfaces, geohistory
- gas giants: Lighter ices, liquids, and gases; no solid surfaces. Vast, spherical oceans w/ small, dense cores
Explain how astronomers can tell whether a planetary surface is geologically young or old
Estimate age #1- count the number of impact craters (impact rates have been constant for several B years). But this only indicates how long since the last impact
Estimate age #2- measure the age of individual rocks via radioactive decay
Describe different methods for dating planets
#1- Impact Craters- this technique hints at the evolution of certain planetary regions. #2- Radioactive Decay- By looking at how much of the parent is left and how many daughters accumulated you can tell how long the decaying process has been taking place and how long ago the rock was formed
Describe the characteristics of planets that are used to create formation models of the solar system
Solar nebula: the Sun and planets formed together from a spinning cloud of gas and dust
Sun, Jupiter, Saturn: formed by the same reservoir of material
Terrestrial planets and Moon: not much light gases and ices; mostly iron and silicones. Inner solar system formation excluded lighter materials. Rock and metal can survive heat (ice and gas would have evaporated)
Describe how the characteristics of extrasolar systems help us to model our own solar system
Planetesimals: material begins to coalesce first by forming smaller objects, precursors of the planets; violent process made the planets heated until they were liquid and gas
Exceptions of the rules of the solar system may be explained by the random collisions of massive collections of planetesimals
Explain the importance of collisions in the formation of the solar system
Planetesimals: material begins to coalesce first by forming smaller objects, precursors of the planets; violent process made the planets heated until they were liquid and gas
Describe the components of Earth’s interior and explain how scientists determined its structure
Crust- only 0.3% of Earth’s mass Mantle- more or less solid Core- dense and metallic --> Outer- liquid --> Inner- probably solid (iron, a lot of high-density nickel and sulfur)
HOW: Seismic waves: waves that spread through the interior of Earth from earthquakes or explosion sites (scientists can learn about the layers this way). They bend or refract so some areas of Earth receive the waves and others don’t
Specify the origin, size, and extent of Earth’s magnetic field
The circulation of liquid metal inside Earth creates an electrical current= a magnetic field
Magnetosphere: the zone within which Earth’s magnetic field dominates over the weak interplanetary magnetic field that extends outward from the Sun
Denote the primary types of rock that constitute Earth’s crust
Igneous rock- cooled molten rock (oceanic basalt and continental granite)
Sedimentary rock- fragments of igneous rock or shells of living organisms deposited by wind or water and cemented together w/o melting
Metamorphic rock- high temperature or pressure alters igneous or sedimentary rock physically or chemically
Primitive rock- the original material out of which the planetary system was made (no material is left on Earth; look on comets, asteroids, small moons)
Explain plate tectonics
a theory that explains how slow motions within the mantle of Earth move large segments of the crust, resulting in gradual “drifting” of the continents as well as the formation of mountains and other large-scale geological features. A mechanism for Earth to transport heat efficiently from the interior out to space; cooling system for the planet
Describe the difference between rift and subduction zones
Rift zones: where plates pull apart from each other. The molten rock rises from below to fill spaces (most are in the oceans). Basaltic lava/igneous rock
Subduction zone: when 2 plates come together, one plate is often forced beneath another (thick continental plates can’t do this but oceanic plates can). Often marked by an ocean trench. Heere earthquakes and volcanoes occur.
Describe the relationship between fault zones and mountain building
Faults (or cracks): where plate boundaries are marked. Motion isn’t smooth → built-up stresses are released in violent slippages that create earthquakes
Mountain building occurs through convergent boundaries
Explain the various types of volcanic activity occurring on Earth
Mark locations where lava rises to the surface. Not all volcanic activity produces mountains
Describe the chemical composition and possible origins of our atmosphere
Composition: Mostly nitrogen, partly water vapor
Three possibilities exist for the original source of Earth’s atmosphere and oceans: (1) the atmosphere could have been formed with the rest of Earth as it accumulated from debris leftover from the formation of the Sun; (2) it could have been released from the interior through volcanic activity, subsequent to the formation of Earth; or (3) it may have been derived from impacts by comets and asteroids from the outer parts of the solar system. Current evidence favors a combination of the interior and impact sources.
Explain the difference between weather and climate
Weather: represents the response of its atmosphere to changing inputs of energy from the Sun
Climate: refers to the effects of the atmosphere that last through decades and centuries. Changes are hard to detect over short periods of time, but accumulation can be devastating
