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Astronomy DTU

Chapters 5-9

Star Self-luminous sphere of gas. Transform matter from lighter elements into heavier ones.
Universe All space along with all the matter & radiation in space. About 14 billion years old, since the Big Bang, & made up of mostly hydrogen with little helium.
Solar System (Our) The Sun, planets, their satellites, asteroids, comets, & related objects that orbit the Sun. About 4 million years old & contain very little hydrogen & helium.
Hydrogen fusion (hydrogen burning) The thermonuclear fusion of hydrogen to produce helium.
Fission Theory Theory that the Moon formed from matter flung off the Earth because the planet was rotating extremely fast
Young solar system Gravity, rotation, & heart shaped
Solar nebula Cloud of gas & dust from which the Sun & the rest of the solar system formed. Diameter of about 100 AU like the "Orion Nebula"
Angular momentum A measure of how much energy an object has stored in its rotation and/or revolution.
Protosun The Sun prior to the time when hydrogen fusion began in its core.
Protoplanetary disk (proplyd) A disk of material encircling a protostar or a newborn star.
Heavy elements stayed in central area lighter elements are pushed out "We are literally made of star dust"
Collisions in the early solar system led to the formation of planets
A planet orbits a star. A moon or natural satellites orbits a planet.
Order of planet formation: Planetesimals > Protoplanets > Planets
Planetesimal Primordial asteroid-like object from which the planets accreted
Protoplanet Embryonic stage of a planet when it is grown because of collisions with planetesimals
Core-acceretion model Traditional theory of giant planet formation that begins with terrestrial planets slowly pulling abundant amounts of water, hydrogen, & helium onto themselves.
Gravitational instability model Theory of giant planet formation in which gases collapse together quickly, without the need for a seed terrestrial planet to form first.
Orbital inclination Tilt or angle of an object's orbital plane around the Sun compared to the ecliptic. All less than 7 degrees.
Craters Circular depression on a celestial body caused by the impact of a meteoroid, asteroid, or comet or by a volcano. Common in early solar system.
Radioactive dating of moon rocks 3.8 billion years ago
Minor debris from the formation of the solar system still exists.
Types of debris from formation of the solar system Asteroid belts, Comets, & Meteoroids
Asteroid belt A 1 1/2 AU wide region between the orbits of Mars & Jupiter in which most of the asteroids are found.
Comet Small body of ice & dust in orbit about the Sun. While passion near the Sun, a comet's vaporized ices gives rise to a coma, tails, & a hydrogen envelope.
Meteoroid Small rock in interplanetary space
KBO's (Kuiper Belt Objects) - Especially big 1s Pluto, Eris, Quaoar & Sedna
Kuiper belt Doughnut-shaped ring of space around the Sun beyond Pluto that contains many frozen comet bodies, some of which are occasionally deflected toward the inner solar system.
Oort cloud Hollow spherical region of the solar system beyond the Kuiper belt where most comets are believed to spend most of their time.
Comparative planetology Orbits - Size - Mass - Density - Spectra - Albedo - Moons
Planet Object orbiting a star that is held together by its own gravitational force in a nearly spherical shape, that is able to clear its neighborhood of debris, & is not the moon (or satellite) of a larger orbiting body
dust & extrasolar planets orbit a breathtaking variety of stars
Earth unique of all planets, covered with 71% mostly liquid water
Atmosphere 4 to 1 mix of nitrogen to oxygen, presently is the third to envelop our planet
Carbon dioxide important because it blocks UV rays & helps form oxygen
Atmospheric pressure 14.7 lbs per square inch Pressure = Force/Area
Pressure = Force/Area
Lower layers of the Atmosphere Troposphere & Stratosphere
Troposphere lowest level of the Earth's atmosphere
Stratosphere second layer in the Earth's atmosphere, directly above the troposphere
Ozone layer lower stratosphere, where most of the ozone in the air exists
Ozone holes
Upper layers of atmosphere Mesosphere & Ionosphere (thermosphere)
Mesosphere layer in the Earth's atmosphere above the stratosphere
Ionosphere (thermosphere) region of Earth's atmosphere, above the mesosphere, in which sunlight ionizes many atoms
Carbon dioxide & Greenhouse effect today 30 degrees centigrade warmer
Plate tectonics produce major changes of Earth's surface proposed by Newton Alfred Wegener introduced idea in 1915
Continental drift - Pangaea - Volcanoes - Mountain formation - earthquakes
Continental drift gradual movement of the continents over the surface of the Earth due to plate tectonics
Earth's interior consists of rocky mantle & an iron-rich core
Planetary differentiation produces a layered structure - core & mantle
Surface density 5520 km/m3 temp 290
center density 5000 K
Created by: 508204118
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