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Test 1: ASTR 101
Scientific Method |
Methodical approach to explore the universe in an objective manner |
Theory |
A framework of ideas and assumptions used to explain particular observations and construct theoritcal models that make predictions |
Constellations |
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 |
Rotation |
The cause of the motion of the stars during one night in the sky |
Revolution |
The cause of the motion of the stars during one year in the sky |
Seasons |
Experienced because Earth's rotation axis is inclined to the ecliptic plane |
Summer/Winter Solstice |
The sun is the highest/lowestin the sky and the length of the day is greatest/shortest |
Equinox |
Day and night are of equal length |
Earth's Precession |
Slow "wobble" of Earth's axis due to the influence of the Moon; Duration: 26,000 years |
The Moon |
Reflects the light from the Sun; As the moon orbits Earth we see Lunar Phases |
Eclipse Seasons |
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 |
Geocentric Model |
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) |
Heliocentric Model |
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) |
Heliocentric Model (additional observations) |
Galileo observed moons orbiting Jupiter; Kepler modeled the observational data of Brahe deriving the three laws of planetary motion |
Keplers 1st Law of Planetary Motion |
Planetary orbits are eclipses with the Sun at one focus |
Keplers 2nd Law of Planety Motion |
A planet moves faster as its orbit takes it closer to the Sun |
Keplers 3rd Law of Planetary Motion |
The semimajor axis of the orbit is related to the orbital period |
Isaac Newton |
Physical principles to explain the planetary motion |
Newtons 1st Law of Motion |
The change the body's velocity, a force must be applied |
Newtons 2nd Law of Motion |
Acceleration is equal to the applied foce divided by the body's mass |
Newtons 3rd Law of Motion |
When bodies interact, the forces between them are always equal and opposite to one another |
Newtons Law of Gravity |
Gravitational force is always attractive and depends of the masses and the distance between the bodies; F=-G(M1M2/r^2) |
Space Exploration |
All the planets have been visited, as well as numerous comets and asteroids |
Typles of Planetary Visits |
Flyby, orbits, and landing |
Gravity Assist in Planetary Visitation |
Spacecraft approaches a planet, passes close by, and then escapes along a new trajectory |
Mercury (Mariner) |
Density of the planet |
Venus (Venera) |
Atmospheric conditions are too extreme, first soft landing |
Mars (Viking, Curiosity, etc.) |
Most visited planet, looking for evidence of life, found strong evidence for underground ice |
Jupiter (Pioneer, Voyager, Galileo) |
Volcanoes on Jupiters moon, liquid under ice surface of Europa, indications of liquid salt water under the surfaces of Ganymede and Calisto |
Saturn (Voyager, Cassini-Huygens) |
Complex organic chemicals in Enceladus and Titan, methane lakes and hydrocarbon sand dunes on Titan |
Uranus and Neptune |
Visited only by Voyager 2 |
Pluto and Kuiper Belt Objects |
Will be visited by New Horizons |
Interstellar Mission (Voyager) |
Measure interstellar fields, particles and waves unaffected by the Sun |
1961 Yuri Gagarin |
1 orbit around the Earth, Vostok 1 |
1965 Alexei Leonov |
1st spacewalk Voskhod 2 |
1969 Neil Armstrong and Buzz Aldrin |
First men on the moon Apollo 11 |
1971 Saluvt |
1st space station |
Apollo Program |
6 landings on the moon |
Space Stations |
Skylab, Mir, ISS (now) |
Space Tourist Era |
2001-present |
Biosphere 2 (1990s) |
Possibility of enclosed biosphere in space colonization |
Mars 500 (2011) |
Psychological and physiological effects of being in an eclosed environment for 520 days, simulating a trip to Mars |
Theories of Planet Formation |
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 |
Irregularities of the Solar System |
Late collisions |
Formation of Planets Stop |
When the star forms and blows away the dust from the disk |
Core Accretion Theory |
Form inner planets, plantertimals collide and form protoplanets |
Gravitational Instability |
Planets form directly from nebular gas, form 4 giant planets |
Giant Planet Migration |
Planets formed at lower temperatures and migrated inwards |