Astronomy 110 Unit 1 Quiz one

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Understand and describe how the apparent motion of stars depends on the Earth's revolution, rotation, and your location
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Understand and describe how the apparent motion of stars depends on the Earth's revolution, rotation, and your location
Polaris, the north star, is fixed in the sky. Stars near Polaris move counter-clockwise.
Explain the nightly apparent motion of both circumpolar and seasonal stars.
Circumpolar stars are stars that never dip below the horizon. They can be seen on any clear night from that location. Depending on where you are on earth, you may see more or less circumpolar stars. Farther north, more stars. At the north pole, all stars are circumpolar. The Equator, no circumpolar stars.Seasonal Stars: stars that rise above and set below the horizon. They rise and set like the sun.
Explain why seasonal stars are not visible all throughout the year.
The sun's bright light causes it to be hidden and a star seen rising at sunset in January, is seen setting at sunset in July, therefore you can't see it.
Describe the motion of objects in the sky [sun, moon, planets, stars] on different time scales [hours, minutes, days, months].
For the time scales of hours and minutes is the earth and the moon, and for day and months is planets and stars
Describe the Gregorian calendar in terms of lunar and solar time scales
We use the Gregorian calendar now and it is a solar calendar. It is based on the revolution of the earth around the sun.
Understand the two reasons why summers are warmer than winters
The Sun's rays hit the earth at a more direct angle during summer and the days are longer than the night so we get more sun.
Briefly describe other calendars used around the world
Other calendars used around the world are lunar, solar, and lunisolar/solilunar
Explain in words and drawings why the Earth exhibits seasons
Understand how the Sun moves across the sky through the seasons
Understand how the Sun moves across the sky through the seasons.
Sun path, sometimes also called day arc, refers to the daily and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.
Explain why the moon exhibits phases
The moon orbits the earth once in about 28 days (about a month.) One half of the moon is always lit. When the earth is in between the sun and the moon, the moon looks full and bright. When the moon is between the Earth and the Sun, the lit half of the moon Is facing away from us. *The orbital path of the Moon causes phases.
Explain what causes tides and how high and low tides are predictedThe moon's gravitational pull on the water causes "bulges" in the ocean on both sides of the planet. The moon pulls the water towards it, and therefore the "earth" is pulled away and water is left behind. That is the other bulge.Tides depend on where the sun and moon are relative to the earth. When the moon and sun are in line with the earth, a high tide happens because the attraction of the moon and sun combine and pull harder. When they form a right angle with the earth, they basically cancel each other out and the tide is low.Describe the geometry required for lunar and solar eclipses. Why do they not happen each month?Lunar Eclipse: The moon passes through the Earth's shadow. The sun, earth, and moon have to be perfectly in line. The full moon has to be at or near one of the nodes. Solar Eclipse: Moon passes between the Earth and the sun.Explain why the same side of the moon always faces EarthThe moon rotates on it's axis at the same rate that the moon orbits earth. Therefore, we always see the same side.Describe how Eratosthenes determined the size of the EarthThey saw a tall stick at noon during summer. It was casting a shadow. They figured out the angle of the shadow was the same as the angle between two cities. They measured the angle of the shortest shadow and found the distance between the two cities was 7/360 of the distance all the way around the earth.What evidence do we have that the Earth is round?1: If a boat "falls" out of sight, you could climb up the mass and see it again. 2: During a lunar eclipse, the shadow cast by the Earth on the moon was round. 3: When you travel from north to south, you lose sight of some stars and see others.Explain how we can determine the size of the moon relative to that of the EarthAristarchus based his estimate of the size of the size of Earth's shadow on the moon during a lunar eclipse. He says earth's radius is 3x that of the moon.Understand the ecliptic and how to find it in the skyBottom line: The ecliptic traces out the apparent annual motion of the sun across the sky. The signs of the Zodiac come from the constellations that lie along this line. You can see the ecliptic yourself by drawing a line connecting the planets and the moonHow is use of the term theory different in science than in everyday conversation?In everyday language, a theory means guess. In science, it is an in depth explanation of something important in nature supported by facts gathered over time. Theories allow scientists to make predictions.Describe the three philosophical assumptions underlying Ptolemy's modelEarth is still center of universe, Earth is imperfect, celestial sphere is perfect. Circles govern heavenly bodiesDescribe Ptolemy's model of the solar system and the evidence it had to support.1. Epicycles and Deferments 2. Earth is no longer exact center of the universe 3. A third point called an equant, from which the deferent does not appear to rotate at a constant rate.Explain retrograde motion of planets in terms of both Ptolemaic and heliocentric models and describe how long it takes to observe this motion.Copernicus created the sun centered model with only the moon orbiting around the earth. simpler model, simpler explanation of retrograde. Retrograde occurs because the planets closest to the sun move faster than the ones further away. Retrograde of Mars occurs when Earth passes a slower moving Mars model had to become more and more complicated to explain retrograde. He devised a series of epicycles whereby the planets moved around small circular paths that in turn moved around large circular orbits around the earth.Describe evidence Galileo found that conflicted with the Ptolemaic model of the solar systemGalileo discovered that Venus has phases like the moon. If Venus were always closer to earth than the sun, we could only see certain phases of the crescent.Explain what conclusions can be drawn about the Ptolemaic and Copernican models of the solar system using the fact that Venus exhibits the full phase.Venus displays phases like Earth's moon. If Venus was always located closer to Earth that the sun (Ptolemaic) the Venus would be illuminated for the back allowing us to observe only various degrees of a crescent phase. Galileo clearly saw Venus in nearly full phase that can only occur if Venus is sometimes on the opposite side of the Sun from us, so Venus was clearly orbiting the Sun. Copernicus theory was that Venus orbited inside Earth's orbit and at a slower rate. He was right. Galileo confirmed this.Describe Kepler's three laws. To what do they apply?Kepler's Laws describe true motions of the planets.1: All planets orbit around the sun, mathematically defined as an ellipse with sun at a focus of the ellipse.2: the speed at which the planet orbits the sun varies so a line drawn from the planet to the sun always stays the same.3: If you take the orbital period of a planet and square it, you get the same value if you take the average orbital radkus and cube it if the period is earth years and the orbital radius is in earth terms.What does the force of gravity depend on?Mass - Newton's third law allows the prediction of orbital size.Explain how Kepler used Tycho's data to determine the orbit of Mars.He used Tycho's volumes of data to serve as a foundation to uncover the correct description of planetary orbits around the sun.Know the shape and location of the following asterisms, visible at 10 pm on June 1 in Bozeman: Cassiopeia, Hercules, Hydra, Virgo and Cepheus.