Test Answers on Astronomy – Astronomy – Flashcards
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Universe
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everything that exists, including the Earth, planets, stars, galaxies, and all matter contained in the cosmos
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Big Bang Theory
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13.7 billion years ago, a theory that stated that a point of singularity expanded outward
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Hubbles Law
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a law that supports the thought of that the universe is still expanding. Doppler Shift
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Proto-galaxy
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an abundant amount of matter and debris that by gravity, causes it to condense and form unorganized groups of stars
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Galaxy
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billions or stars, gas, and dust held together by gravity
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Types of Galaxies
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Spiral, Elliptical, and Irregular
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Spiral
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a type of "disk" like galaxy with arms that have bright nuclei, has young blue and yellow stars, and is the most common
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Milkyway
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this galaxy contains about 200 billion stars, rotates counter-clockwise at 600,000 mph, has an arm width of 1000 light years, and a 200,000 light year width of the galactic bulge. Our galaxy
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Elliptical
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A type of galaxy that is spherical to lens-shape, has no arms, has a concentrated nuclei, and has yellow, orange, and red stars
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Irregular
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The third type of galaxy in which it is the smallest of all types, they are very faint, they are the least common, and the stars are spread out
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Evolution of Galaxies
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Elliptical to Spiral to Irregular
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Solar System
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a system of planets, asteroids, meteors, satellites, and comets that are captured in orbit around a central star or stars
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Light Year
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the distance light travels in one year. 9.46 trillion kilometers or 5.87 trillion miles. Travels at 300,000 kilometers per second
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Andromeda
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the nearest galaxy at 2 million light years away from us.
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Parsec
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a larger astronomical unit used to measure distances between galaxies. Equal to 3.26 light years
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Megaparsec
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One million parsecs or 3,260,000 light years
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Astronomical Unit
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used to measure distances within our solar system . 150,000,000 kilometers
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Stars
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massive, luminous spheres of plasma held together by gravity and kinetic pressure. Composed of primarily hydrogen and helium
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The Sun
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4.6 billion years old, takes 24-26 days to rotate. Produces energy by fusion. Our primary source of energy and heat
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Solar Prominences
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areas of which gases can shoot tens of thousands of miles from the Sun's surface. Makes a "P" like shape
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Solar Flares
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violent eruptions that shoot into space that form an "F" like shape
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Sun Spots
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cooler, dark regions on the sun's surface that cause interference in Earth's satellites. Has a cyclic relationship of eleven years
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Layers of the Sun
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core to radiative zone to convection zone to photosphere to chromosphere to corona
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Core of the Sun
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Fussion creates energy in this spot of the sun. As hot as 15,000,000 degrees Celsius
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Radiative Zone
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the spot of the sun where energy escapes the core into the convection zone
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Convection Zone
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the spot where energy moves in an circular pattern until it reaches the "surface".
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Chromosphere
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the sun's lower atmosphere, over the photosphere
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Photosphere
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visible part of the sun, out shines the chromosphere
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Corona
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only visible when in an solar eclipse. Outermost part of the sun
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Stellar Magnitude
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how bright a star is in the sky. The apparent brightness from earth.
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Absolute Magnitude
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the true brightness of stars at 10 parsec away. Brighter stars have negative numbers while dimmer stars have positive numbers
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Luminosity
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the total output of radiant energy per second. Depends on temperature, mass, and the radius
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What is the color of stars when they are there hottest?
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Blue
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What is the color of stars when they are there coolest?
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Red
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What are all of the steps of the evolution of stars?
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Proto star to Main Sequence to Red Giant to White Dwarf to Black Dwarf
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Nebular Hypothesis
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introduced by Sir James Jean. Stated that when a nebular cloud reaches a certain mass and length, the likelihood of that cloud of collapsing into a solar system is high
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Steps of the Solar System
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Nebular Cloud to spinning of the cloud to form a model like saturn to the initial formation of planets to the planets known today
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How do Planets Form?
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initially small particles of as and dust stick together via their electrostatic attraction, as they grow larger, their gravity becomes stronger and it attracts more particles and then once they gain enough mass, they overcome there rigid body and form a planet
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Chemical Differentiation
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a process in which heavy elements sink towards the center of an object of an object while the lighter elements remain closer to the surface
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Mercury
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smallest planet, closest to sun, most extreme temperature change, thinnest atmosphere
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Venus
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hottest planet, thickest atmosphere, rotates up-side-down
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Earth
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only planet to have water and to sustain life
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Mars
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fourth planet from the sun, has an iron body
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Jupiter
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largest planet, made up of hydrogen and helium, has a great red spot
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Saturn
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least dense planet, most developed rings
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Uranus
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vertical ring system, high concentration of methane
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Neptune
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farthest planet of all, has a great blue spot
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What makes a planet a planet?
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an object that orbits the sun, has enough mass to overcome rigid body forces, has cleared the neighborhood around its orbit, not a satellite
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What classifies a dwarf planet?
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is in an orbit around the sun, has enough mass to overcome rigid body forces, has not cleared the neighborhood around its orbit
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What are smaller solar system bodies?
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a category that collectively refers to all other celestial bodies orbiting our sun
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Aristotle
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Greek Philosopher who introduced the four elements of the earth. Water, Earth, Fire, and Air
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Ptolemy
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Greek and Egyptian, introduced to epicycle and made the geocentric model more accurate
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Tycho Brahe
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Danish, designed and built astronomical instruments, mapped the night sky, observed planets and the first supernova
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Copernicus
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developed the heliocentric model, wrote the "Revolution of Heavenly Bodies"
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Galileo
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invented astronomical instruments, discovered moons of jupiter. Father of modern science
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Kepler
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proposed the three laws of planetary orbits
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What is Law #1 of Kepler's three laws?
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The Law of Ellipses
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What are the two points of an ellipse called?
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foci or focal points
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Eccentricity
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how round an orbit is or how oval like an orbit is.
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What is the equation for eccentricity?
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eccentricity=distance between the two foci/Length of Major axis
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Major Axis
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the length between the two most outer parts of the ellipse
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What is the unit for eccentricity?
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Nothing
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Rotation
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the spinning of the earth in its axis
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Precession
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a minor change in the orientation of the axis of rotation within a rotating body
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Who came up with the idea of precession?
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Hipparchus
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How long is the period of time it takes for the earth to go through a full cycle of precession?
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26,000 years
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What will be our north star in 13,000 years?
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Vega
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Revolution
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the movement of the earth in the orbit around the sun
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Retrograde Motion
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movement of an object in the opposite direction to the movement of another object (the wandering of an object)
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What planet appears to "wander" in the sky due to retrograde motion?
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Mars
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Parallax
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an apparent change in the direction of an object, caused by a change in observable position that provides a new line of sight
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What are the two factors in why stars seem to wander in the sky?
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Orbital Velocity and Parallax
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Kepler's Law #1 Definition
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Kepler stated that all satellites orbit the sun in ellipses.
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How long does it take to complete one full rotation around the sun on earth?
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365.26 days
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What is the Earth's eccentricity?
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0.017
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Perihelion
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Occurs around January 4th, closest time the Earth is closest to the sun
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Aphelion
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Occurs around July 3rd, farthest away from the sun at this time in our revolution
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How far away are we from the sun at Aphelion?
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152.6 million kilometers
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How far away are we from the sun at Perihelion?
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147.5 million kilometers
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Gravity
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the force of attraction between any two massive bodies
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Inertia or Path of Inertia
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the resistance of an object to a change in its motion
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What two forces cause our revolution around the sun an ellipse?
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Gravity and the Path of Inertia
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What is the force in-between gravity and inertia called?
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the NET force
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Orbital Velocity
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The speed at which a planetary body orbits around a star or stars
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What is Kepler's Law #2?
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The Law of Equal Areas
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What does Kepler's 2nd law state?
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this law states that an imaginary line joining to the sun will sweep over equal areas in equal time
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What is Kepler's Law #3
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the Harmonic Law
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What does Kepler's 3rd law state?
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this law states that a planet's period of revolution depends on the distance from the sun
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What is the equation for Kepler's Law #3?
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P squared = r cubed
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What does "P" mean in Kepler's 3rd Law?
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it means the amount of earth years it takes for a planet to complete one rotation
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What does the "r" stand for in Kepler's 3rd Law?
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it means the distance between a planet and the sun in astronomical units
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What is the equation for Kepler's 3rd law if the star has a different mass that our Sun?
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m=r cubed / P squared
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What is the Earth's main source of energy we get?
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energy that comes from the sun, about 99.7%
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What are the other main sources of energy that the Earth gets?
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Tides. Tides cause friction by waves, friction causes heat, and heat causes energy. Also stars in the sky produce light, light produces heat, and heat produces energy
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What are the eight types of energy?
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cosmic, gamma, x-ray, ultraviolet, light spectrum, infrared, microwave, and then radio waves
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Insolation
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incoming solar radiation. All forms of electromagnetic energy that reaches the earth
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What are factors that cause the intensity of insolation to fluctuate?
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The angle of insolation, the duration of insolation, the color and texture of the surface, the cloud cover, and the proximity to water
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What are the two times when the Isolation changes?
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Yearly and daily (sunset and sunrise)
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When the sun is at your zenith, the isolation is _______?
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high
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When the sun is at your horizon or at an angle, the isolation is ________?
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low
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Sub-solar point
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the position on the earth where the isolation angle is 90°
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Which evidence supports the Big Bang Theory?
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existence of cosmic background radiation
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What force was mostly responsible for the initial contraction of the gas cloud that formed our solar system?
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electrostatic
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The atmosphere of Venus is composed primary of what?
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Carbon-dioxide
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As a rotating cloud collapses, its rate of rotation does what?
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increase
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What is the primary element of Jovian planets?
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hydrogen
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What is the average distance from the Sun to the asteroid belt?
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503 million kilometers
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What celestial phenomenon most affects radio communication and other electrical atmospheric changes for us on Earth?
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solar flares
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What factor determines whether a star will evolve into a white dwarf, a neutron star, or a black hole?
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the initial mass
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What type of star is the youngest?
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Blue stars
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What is the interstellar cloud formed during the formation of our solar system called?
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A nebula
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What type of energy causes Venus to have a hotter surface temperature than Earth?
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infrared or short-wave energy
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How would you find out the altitude of the sun on the summer solstice in the northern hemisphere?
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1.Take your latitude and subtract 23.5° from it. 2. Then do 90°-your answer from step 1.
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How would you find out the altitude of the sun on the winter solstice in the northern hemisphere?
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1.Take your latitude and add 23.5° 2.Then you subtract your answer from 90°
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Where do the direct rays from the sun hit on the earth at the summer solstice?
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At the tropic of cancer 23.5° N
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Where is the north pole pointing at the event of the summer solstice ?
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The north pole points towards the sun
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Where do the direct rays from the sun hit on the earth at the winter solstice?
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At the tropic of capricorn 23.5°S
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Where do the direct rays from the sun hit on the earth at the vernal and autumnal solstice?
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At the equator 0°
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How do you find the sun's altitude in the Northern Hemisphere (June 22nd-September 20th)?
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1.Take your latitude and subtract the sub-solar point 2.Subtract answer from step one from 90°
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How do you find the sun's altitude in the Northern Hemisphere (September 22nd-December 20th)?
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1.Take your latitude and add it to the sub-solar point 2.Subtract answer from step one from 90°
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How do you determine the intensity of isolation of the sun?
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By using the SIN function and multiplying it by 100 ex. SIN45(100)=70.7%
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Parallelism of Earth's Axis
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axis always points the same direction
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How do you get a good grade?
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You say focused, calm, and confident GOOD LUCK AND OUTSMART YOUR SENSES
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What type of galaxy is this?
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spiral galaxy
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What type of galaxy is this?
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elliptical galaxy
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What type of galaxy is this?
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irregular galaxy
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What hemisphere are you in and which way are you looking depicted by this star trail?
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Northern Hemisphere and North
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What direction are you looking depicted by these star trails?
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East
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What direction are you looking in as these star trails show?
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West
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What are the two of the three pieces of evidence that prove that the Earth rotates?
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Star Trails and the Coriolis Effect
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Star Trails
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time lapse photos of stars that show these circular patterns in the sky due to the rotation of the earth
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How fast do the star trails appear to move in the sky?
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the stars appear to move at 15° per hour
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How long does it take to complete a full rotation of the Earth?
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23 hours 56 minutes 4 seconds
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Sidereal Day
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the day where it takes the earth 23 hours 56 minutes and 4 second to complete a revolution
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Solar Day
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when the earth moves back to the same position as in alignment with the sun as it was the day before. So the Earth has to rotate an extra degree
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Circumpolar Stars
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stars that never appear to rise nor set while depicted in their star trails
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Coriolis Effect
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the apparent deflection of a free moving object that moves within a rotating body
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What direction do objects appear to deflect in the Northern Hemisphere do to the Coriolis Effect?
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they deflect to their right
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What direction do objects appear to deflect in the Southern Hemisphere do to the Coriolis Effect?
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they deflect to their left
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What are the three main pieces of evidence that support that the Earth revolves around the Sun?
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We can observe different constellations in different seasons, constellations are only visible when the dark side of the earth faces the constellations, and seasonal changes in a yearly cycle
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What is the speed of rotation at the North Pole?
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about 0 mph
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What is the speed of rotation at the equator?
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about 1,000 mph
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What are the three main pieces of evidence that prove that the Earth rotates?
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Star Trails, the Coriolis Effect, and the Foucault Pendulum
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Which of the three pieces of evidence on how the Earth rotates is the best piece of evidence?
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the Foucault Pendulum
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Who was the first to create the Foucault Pendulum?
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Jean Bernard Leon Foucault
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How does the moon move across the sky?
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it moves in the sky from east to west
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How much of the moon is illuminated at all times?
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half of the moon
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How long does it take to go through a lunar cycle?
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29.5 days
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How much is the moons orbit tilted by?
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5°
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How long does it take to revolve around the Earth?
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27.5 days
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How long does it take for the moon to complete a full rotation around its axis?
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27.5 days
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What is the moons orbit called since the rotation and period of revolution is the same?
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Synchronous Orbit
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How long is a Sidereal Month?
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27.3 days
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How long is a Lunar Month?
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29.5 days
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What is the scientific name for when the moon is closest to Earth?
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Perigee
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How far away is the moon from Earth at Perigee?
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356,410 km
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What is the scientific name for when the moon is farthest to Earth?
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Apogee
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How far away is the moon from Earth at Apogee?
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406,700 km
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Earthshine
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sunlight reflected off the Earth's surface back onto the moon (why we see the dark side of the moon faintly)
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Which phase of the moon's lunar cycle is the phase where all of the moon appears to be in darkness?
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New Moon
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Which phase of the moon is when the near side of the moon is 100% illuminated?
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Full Moon
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What natural phenomenon cause the moon the appear a greenish color during the gibbous phase?
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The Green Gibbous
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What is the name of the natural phenomenon that fuses the moon to have a red to orange coloring?
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The Harvest Moon
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When does a blue moon occur?
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When there is two full moons in a month. The second full moon is the rare part of this occurrence
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What is the position of the Earth called when the moon is at a total lunar eclipse?
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the Earth is at umbra
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What is the position of the Earth called when the moon is in a partial eclipse?
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the Earth is at penumbra
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Umbra
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darker part of the shadow casted by the Earth onto the moon
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Penumbra
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lighter part of the shadow casted by the Earth onto the moon
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Solar Eclipse
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a natural phenomenon in which the moon blocks out the light from the sun. Only happens for a brief moment
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Lunar Eclipse
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a natural phenomenon in which the Earth blocks out the light out from the sun that was potentially going to be casted upon the lunar surface. Lasts for a longer time than other eclipses
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What lunar phase can a lunar eclipse only occur?
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Full Moon (eclipses answer)
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Shadow
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an area of darkness retaining to Solar and Lunar Eclipses
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What lunar phase can a solar eclipses only occur?
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New Moon (eclipses answer)
