Earth & Space Science (US High School)
NGSS-aligned high school Earth & Space Science: Earth's place in the universe, Earth's interior and surface systems, history of Earth, weather and climate, and human sustainability.
Ämne: Geografi · Nivå: Gymnasium (16–19) · 432 kort
Innehåll
- The Big Bang theory states that the universe began about 13.8 billion years ago from an extremely hot, dense initial state and has been expanding ever since.
- Cosmic microwave background (CMB) radiation is the faint, nearly uniform afterglow of the Big Bang, providing strong observational evidence for the theory.
- Redshift of distant galaxies shows that the universe is expanding: more distant galaxies recede faster, consistent with Hubble's law (v = H₀d).
- Stellar nucleosynthesis is the process by which elements heavier than hydrogen and helium are formed inside stars through nuclear fusion.
- Elements heavier than iron (such as gold, uranium, and platinum) are formed primarily during supernova explosions and neutron star collisions.
- The Sun is a main-sequence G-type star that fuses hydrogen into helium in its core, producing energy that powers Earth's climate, weather, and life.
- The solar system formed about 4.6 billion years ago from a rotating cloud of gas and dust called a solar nebula, which collapsed under gravity.
- The nebular theory explains that as a solar nebula collapsed, the Sun formed at the center while planets accreted from leftover dust and gas in a flattened disk.
- Terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, and rocky; gas giants (Jupiter, Saturn) and ice giants (Uranus, Neptune) are large and mostly gaseous.
- Earth is approximately 4.54 billion years old, an age determined primarily by radiometric dating of meteorites and the oldest terrestrial minerals.
- Earth rotates on its axis once every ~24 hours, causing day and night, and revolves around the Sun once every ~365.25 days.
- Earth's axis is tilted ~23.5° relative to its orbital plane, which is the primary cause of seasons.
- The Moon is Earth's only natural satellite, formed about 4.5 billion years ago, likely from debris ejected by a giant impact between Earth and a Mars-sized body (Theia).
- Lunar phases are caused by the changing relative positions of Earth, Moon, and Sun, which alter how much of the Moon's sunlit half we see.
- Ocean tides are caused primarily by the gravitational pull of the Moon and secondarily by the Sun; spring tides occur during new and full moons, neap tides during quarter moons.
- A solar eclipse occurs when the Moon passes between the Sun and Earth, blocking sunlight; a lunar eclipse occurs when Earth blocks sunlight from reaching the Moon.
- Kepler's First Law: planets orbit the Sun in ellipses with the Sun at one focus, not in perfect circles.
- Kepler's Second Law: a line connecting a planet to the Sun sweeps out equal areas in equal times, meaning planets move faster when closer to the Sun.
- Kepler's Third Law: the square of a planet's orbital period (T) is proportional to the cube of its average orbital radius (a): T² ∝ a³.
- Newton's law of universal gravitation: every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance.
- A light-year is the distance light travels in one year, about 9.46 × 10¹² km, used to measure distances between stars and galaxies.
- One astronomical unit (AU) equals the average Earth-Sun distance, about 1.496 × 10⁸ km, used to measure distances within the solar system.
- The Milky Way is a barred spiral galaxy containing 100–400 billion stars; the Sun is located on one of its spiral arms about 26,000 light-years from the galactic center.
- The Hertzsprung-Russell (H-R) diagram plots stars by luminosity vs. surface temperature, revealing groupings such as main sequence, red giants, and white dwarfs.
- A star's life cycle depends on its mass: low-mass stars become white dwarfs, while high-mass stars end as supernovae leaving behind neutron stars or black holes.
- Earth's interior is divided into the crust (thin outer rock layer), mantle (hot, plastic silicate rock), outer core (liquid iron-nickel), and inner core (solid iron-nickel).
- The lithosphere is the rigid outer shell of Earth that includes the crust and uppermost mantle; it is broken into tectonic plates.
- The asthenosphere is the partially molten, ductile layer of the upper mantle beneath the lithosphere; tectonic plates slide on top of it.
- Continental crust is thick (~30–50 km), less dense, and felsic (granitic); oceanic crust is thin (~5–10 km), denser, and mafic (basaltic).
- Earth's magnetic field is generated by convection of molten iron in the outer core (the geodynamo) and shields the planet from harmful solar radiation.
- Plate tectonics is the theory that Earth's lithosphere is broken into plates that move over the asthenosphere, driven by mantle convection.
- Divergent plate boundaries occur where plates move apart, forming mid-ocean ridges and creating new oceanic crust (e.g., Mid-Atlantic Ridge).
- Convergent plate boundaries occur where plates collide, forming mountain ranges, volcanic arcs, or deep ocean trenches via subduction.
- Transform plate boundaries occur where plates slide horizontally past each other, producing earthquakes (e.g., San Andreas Fault in California).
- Subduction occurs when a denser oceanic plate slides beneath a less dense plate at a convergent boundary, often producing volcanoes and deep trenches.
- Seafloor spreading is the process by which new oceanic crust forms at mid-ocean ridges and pushes older crust outward, recorded in magnetic stripes.
- Continental drift, proposed by Alfred Wegener in 1912, suggested that continents were once joined as a supercontinent called Pangaea that broke apart.
- Evidence for plate tectonics includes matching coastlines, identical fossils on different continents, matching rock formations, paleomagnetic stripes, and earthquake/volcano patterns.
- Hotspots are areas of unusually high mantle heat flow that produce volcanism within a plate (e.g., the Hawaiian Islands, Yellowstone).
- Earthquakes are sudden releases of energy in Earth's crust caused by movement along faults; the energy travels as seismic waves.
- P-waves (primary, compressional) travel through solids and liquids; S-waves (secondary, shear) travel only through solids, which is how scientists know the outer core is liquid.
- The Richter scale and moment magnitude scale (Mw) both express earthquake magnitudes logarithmically: each whole number step represents ~32× more released energy.
- A volcano is an opening in Earth's crust where magma, gases, and ash erupt. Types include shield, composite (stratovolcano), and cinder cone volcanoes.
- The three main rock types are igneous (from cooled magma/lava), sedimentary (from compacted sediments), and metamorphic (from heat/pressure altering existing rock).
- Intrusive (plutonic) igneous rocks like granite cool slowly underground and have large mineral crystals; extrusive (volcanic) rocks like basalt cool quickly on the surface with small crystals.
- Sedimentary rocks form through weathering, erosion, transport, deposition, compaction, and cementation. Examples include sandstone, shale, and limestone.
- Metamorphic rocks form when heat and pressure transform existing rocks without melting them. Examples: shale → slate, limestone → marble, granite → gneiss.
- The rock cycle describes the continual transformation of rocks among igneous, sedimentary, and metamorphic forms via melting, cooling, weathering, and metamorphism.
- A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a crystalline atomic structure.
- Mohs hardness scale ranks mineral hardness from 1 (talc) to 10 (diamond) and is used to identify minerals.