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30 Cards in this Set
- Front
- Back
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What is a constellation?
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A constellation is any one of the 88 areas into which the sky - or the celestial sphere - is divided. The term is also traditionally and less formally used to denote a group of stars visibly related to each other in a particular configuration or pattern.
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What is the celestial sphere?
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In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of "gigantic radius", concentric and coaxial with the Earth. All objects in the sky can be thought of as lying upon the sphere. Projected, from their corresponding geographic equivalents, are the celestial equator and the celestial poles. The celestial sphere projection is a very practical tool for positional astronomy.
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Why do we see a band of light called the Milky Way in our sky?
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Our solar system is in that disk. When we look at the Milky Way in the sky, we are looking along that disk.
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Describe the basic features of the local sky…horizon, meridian, zenith….
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Horizon is the boundary between Earth and the sky. The zenith is the point directly overhead. The meridian runs due south to due north through the zenith.
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Why does NASA launch satellites here?
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By launching at the Equator you get 6% of your launch velocity for free.
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What is the Earth’s rotational speed at the North Pole?
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0 mph
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What is the ecliptic?
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The annual path of the Sun through the celestial sphere, which is a projection of ecliptic plane
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What is the cause of the seasons on Earth?
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The tilt of Earth's axis causes the seasons. The axis points in the same direection throughout the year, thus as the Earth orbits the Sun, sunlight hits different parts of Earth more directly at different times of the year.
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What are the dates of the equinoxes? Solstices?
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Equinoxes: March 21th and September 23rd. Solstices: June 22th and December 22rd
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A year is 365.25 days long. Was that always the case?
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No
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How many degrees do stars move in an hour?
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One degree
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How does the night sky change through the year?
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Our nightsky lies in different directions in space as we orbit the sun. Constellations vary with latitude because your latitude determines orientation of your horizon relative to the celestial sphere.
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What is special about Greenwich that the prime meridian of the world is located there?
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Nothing
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Jackson Square in New Orleans is 90º west of Greenwich England. If it is 6 pm in Greenwich, what time is it in New orleans?
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9 pm
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Why do we see phases of the Moon?
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Phase of the moon depends on its position relative to the sun as it orbits earth.
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Name the phases of the moon in order.
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New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent
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What conditions are necessary for an eclipse?
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When the moon crosses the ecliptic plane only at the two nodes, and must be full or new
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Why do planets sometimes seem to move backwards relative to the stars?
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Apparent retrograde motion
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What is parallax?
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A slight apparent shift in stellar positions over the course of the year
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What is an arc-second?
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The smallest unit used to measure the sky in angels
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Why did the ancient Greeks reject the idea that the Earth goes around the Sun, even though it offers a more natural explanation for planetary motion?
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They believed in the Ptolomaic model to explain retrograde motion
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A lunar eclipse occurs during what phase of the moon?
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Full
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How did the Greeks lay the foundations for modern science?
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Developed models, emphasized importance of having predictions of those models agree with observations of nature,
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What was the Ptolemaic model?
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Explained retrograde motion by having each planet move on a small circle whose center moves around earth on a larger circle
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What are Kepler’s three laws of planetary motion?
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1) Orbit of each planet is an ellipse with the sun at one focus
2) As a planet moves around its orbit it sweeps out equal ares in equal times 3) More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship. p2=a3 |
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Briefly describe the roles of Copernicus, Tycho, Kepler, and Galileo.
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Copernicus created a sun-centered model of the solar system designed to replace the Ptolemaic model, but no more than Ptolemy's because Copernicus still used perfect circles.
Tycho's accurate, naked-eye observations provided the data needed to improve on Copernicus's model. Kepler found a model of planetary motion that fit Tycho's data. |
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How can we distinguish science from nonscience?
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Modern science seeks explanations for observed phenomena that rely on natural causes, science progresses through the creation and testing of models of nature that explain the observations as simple as possible, and a scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.
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What is gravitational potential energy?
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Depends on objects mass, strength of gravity, and distance object could potentially fall. In space an object or gas cloud has more gravitational energy when it is spread out than contracted. A contracting cloud converts gravitational potential energy to thermal energy.
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What is the basic structure of an atom?
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Nucleus containing neutrons and protons, electron cloud containing electrons
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Distinguish between atomic number and atomic mass number.
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Atomic number is the number of protons in the nucleus. Atomic mass number is the number of protons and neutrons
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