Test 1: ASTR 101
48 Cards in this Set
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Scientific Method
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Methodical approach to explore the universe in an objective manner
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Theory
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A framework of ideas and assumptions used to explain particular observations and construct theoritcal models that make predictions
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Constellations
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Projection of the stars in the celestial sphere centered on Earth
The stars of a particular constellation are not gravitationally connected, which means that they can be at completely different distances
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Rotation
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The cause of the motion of the stars during one night in the sky
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Revolution
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The cause of the motion of the stars during one year in the sky
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Seasons
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Experienced because Earth's rotation axis is inclined to the ecliptic plane
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Summer/Winter Solstice
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The sun is the highest/lowestin the sky and the length of the day is greatest/shortest
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Equinox
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Day and night are of equal length
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Earth's Precession
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Slow "wobble" of Earth's axis due to the influence of the Moon; Duration: 26,000 years
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The Moon
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Reflects the light from the Sun; As the moon orbits Earth we see Lunar Phases
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Eclipse Seasons
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Because the Moon's orbit around Earth is slightly inclined with respect to the ecliptic, solar and lunar eclipses do not occur every month--> only during eclipse seasons
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Geocentric Model
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Ptolomaic model where Earth is in the center of the universe; predicted that planets moved on small circles (epicycles) whose centers orbited Earth on larger circles (deferents)
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Heliocentric Model
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Earth and other planets orbit the Sun; model accounts for retrograde motion and the observed size and variations in brightness of the planets in a straightforward way (Copernicus)
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Heliocentric Model (additional observations)
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Galileo observed moons orbiting Jupiter; Kepler modeled the observational data of Brahe deriving the three laws of planetary motion
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Keplers 1st Law of Planetary Motion
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Planetary orbits are eclipses with the Sun at one focus
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Keplers 2nd Law of Planety Motion
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A planet moves faster as its orbit takes it closer to the Sun
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Keplers 3rd Law of Planetary Motion
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The semimajor axis of the orbit is related to the orbital period
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Isaac Newton
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Physical principles to explain the planetary motion
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Newtons 1st Law of Motion
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The change the body's velocity, a force must be applied
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Newtons 2nd Law of Motion
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Acceleration is equal to the applied foce divided by the body's mass
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Newtons 3rd Law of Motion
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When bodies interact, the forces between them are always equal and opposite to one another
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Newtons Law of Gravity
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Gravitational force is always attractive and depends of the masses and the distance between the bodies; F=-G(M1M2/r^2)
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Space Exploration
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All the planets have been visited, as well as numerous comets and asteroids
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Typles of Planetary Visits
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Flyby, orbits, and landing
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Gravity Assist in Planetary Visitation
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Spacecraft approaches a planet, passes close by, and then escapes along a new trajectory
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Mercury (Mariner)
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Density of the planet
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Venus (Venera)
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Atmospheric conditions are too extreme, first soft landing
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Mars (Viking, Curiosity, etc.)
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Most visited planet, looking for evidence of life, found strong evidence for underground ice
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Jupiter (Pioneer, Voyager, Galileo)
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Volcanoes on Jupiters moon, liquid under ice surface of Europa, indications of liquid salt water under the surfaces of Ganymede and Calisto
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Saturn (Voyager, Cassini-Huygens)
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Complex organic chemicals in Enceladus and Titan, methane lakes and hydrocarbon sand dunes on Titan
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Uranus and Neptune
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Visited only by Voyager 2
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Pluto and Kuiper Belt Objects
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Will be visited by New Horizons
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Interstellar Mission (Voyager)
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Measure interstellar fields, particles and waves unaffected by the Sun
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1961 Yuri Gagarin
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1 orbit around the Earth, Vostok 1
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1965 Alexei Leonov
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1st spacewalk Voskhod 2
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1969 Neil Armstrong and Buzz Aldrin
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First men on the moon Apollo 11
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1971 Saluvt
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1st space station
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Apollo Program
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6 landings on the moon
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Space Stations
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Skylab, Mir, ISS (now)
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Space Tourist Era
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2001-present
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Biosphere 2 (1990s)
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Possibility of enclosed biosphere in space colonization
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Mars 500 (2011)
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Psychological and physiological effects of being in an eclosed environment for 520 days, simulating a trip to Mars
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Theories of Planet Formation
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Cloud of gas and dust contracts; fragment flattens into a disk; planets inherit properties from the rotating disk; There is differentiation of the planets of the Solar System
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Irregularities of the Solar System
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Late collisions
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Formation of Planets Stop
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When the star forms and blows away the dust from the disk
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Core Accretion Theory
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Form inner planets, plantertimals collide and form protoplanets
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Gravitational Instability
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Planets form directly from nebular gas, form 4 giant planets
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Giant Planet Migration
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Planets formed at lower temperatures and migrated inwards
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