Astronomy_ Test 1

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Feb 20, 2024

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Astronomy/Solar System Notes (from your tutor) Homework 2: Earth’s Rotation (Pearson Astronomy) As Earth spins on its axis, the Sun, Moon, stars and everything beyond Earth appears to move across the sky. When thinking about observing the sky from a spinning Earth, it is usually easiest to imagine a counter-clockwise spinning Earth as seen from above its North Pole. The Figure at right shows the Earth as seen from above the north pole. An observer on the equator experiences local noon. A, B, and C mark observer positions with different local times. D, E, and F mark the possible positions of objects in the sky. (a) Which observer position corresponds approximately to midnight B (b) Which observer position corresponds approximately to 6 am? C (c) Which observer position corresponds approximately to 6 pm? A (d) The bright star Rigel in the constellation of Orion is seen high in the sky at midnight. Which position (D, E, or F) is most consistent with this observation? E (e) If the Moon is high above an observer’s head at sunrise, which position (D, E, or F) is most consistent with this observation? D (f) Objects in the sky appear to rise and set because Earth spins on its axis. If a star rises in the East at 8:00 pm on a Monday night, how many hours must pass before it rises again? About 24 hours (g) If Earth is spinning twice as fast, only taking about 12 hours to spin once, how long would it take for a star to appear to move across the sky from the Eastern to the Western horizon? About 6 hours
(h) From the mid-latitudes of the Northern hemisphere, the seven stars of the Big Dipper never appear to rise and set, but to move around the North Star (Polaris) counter-clockwise. In the middle frame below, what should be the location of the Big Dipper with respect to Polaris? Above Polaris 1/26: Pre Class Questions Is there any location on Earth where an observer can see all 88 constellations in the course of one year ? No, there is not a single location on Earth where a person can see all 88 constellations in the course of one year. The visibility of a constellation depends on the latitude in which you are standing and also the tilt of the Earth’s axis. If you are near the equator, you can see a large portion of the celestial sphere over the course of a year, but not all 88 constellations due to the tilt of the Earth’s axis. Use your own words, explain the following terms: Celestial Sphere: it is an imaginary sphere surrounding the Earth. The stars, plants, and galaxies appear to be projected when viewed from Earth. It is a helpful tool in astronomy for visualizing the position of celestial bodies as they move across the sky with regards to the Earth’s rotation. Zenith: it is the highest point in the sky but is different for each observer depending on their location (longitude and latitude) on the Earth. Meridian: it is an imaginary line that runs through an observer’s zenith and connects the north and south poles. It also represents the highest point in the sky reached by the Sun, stars, and other celestial objects as they cross the observer’s line of sight. It cuts the sky into two halves. In the eastern half, the celestial objects rise and in the western half, the celestial objects set.
1/29: Pre Class Questions Do all stars rise and set every day? Explain Most stars do appear to rise and set every day. The stars rise up from the east horizon and set over the west horizon. Every 24 hours the stars that rise and set are above the horizon exactly half of the time. There will be times when the sun is too bright to see some of these stars. There are some stars that neither rise or set and they are called Circumpolar Stars. They are above the horizon every day of the year. When the sun is out and it’s daytime you can not see them, but they remain in the sky. They circle endlessly in what appears to be a counterclockwise pattern around the North Star. These constellations are visible in the northern night sky any night of the year. \ In North America, if a star rises due east at sunset, at what time will it be highest in the sky? In what direction should you face to see it? Explain If a star rises in the east at sunset in North America, it will be highest in the sky at approximately midnight. The star will move across the sky towards the west. When the star reaches its highest point this is known as its culmination point. In order to see it, a person will need to look toward the south. The reason you need to look toward the south is because of the Earth's rotation on its axis. Even though the star is moving east to west, it will also appear to move slightly south as a result of the Earth’s rotation. HOMEWORK 3: Position (a) Is the horizon shown a real physical horizon or an imaginary plane that extends from your observing location on Earth out to the stars? Imaginary. The horizon the observer sees is real, but the one shown denotes where the observer's line-of-sight along the real horizon intersects the celestial sphere.
(b) Can the observer shown see a star when it is located below the horizon? No, only stars above the horizon can be seen by the observer (c) Is either Star A or B ever in an unobservable position? If so, which position(s)? Yes, star A is unobservable at position 4 when it is below the horizon. Star B is never below the horizon, so it is never in an unobservable position. (d) When a star travels from a position below the observer's horizon to a position above the observer's horizon, is that star rising or setting? The star is rising. (e) When a star travels from a position above the observer's horizon to a position below the observer's horizon, is that star rising or setting? The star is setting. (f) Star A is just visible above your eastern horizon at Position 1. At which of the numbered positions is it just visible above your western horizon? Position 3 (g) At which position, if any, does star B rise and set? Star B does not rise or set because it is circumpolar (h) two students are discussing their answers to Part G student 1: locations b1 and b3 are on my horizon because they are rising and setting just like a1 and a3. student 2: figure 1 shows that star b is as low as it will get when it is just above the northern horizon at b4. so star b never goes below the horizon. Do you agree or disagree with either or both of the students? Explain. Agree with student 2. Rising and setting are defined with respect to a horizon. A star's path must cross the horizon to rise and set. Star B never crosses the horizon, and in fact, is nearest the horizon only when it is due north. (i) Drag the direction labels into the correct boxes. (j) For each indicated position, match where in the sky you must look to see the star at that time. Each description has two pieces of information: the direction you must face and how far above the horizon you must look. A1: East Low A2: South High A3: West Low
A4: Cannot see STAR B4: North Low B1: Northeast High B2: Directly overhead: Zenith B3: Northwest Low (k) Does star B ever set? No, star B is circumpolar https://quizlet.com/463692681/astronomy-1504-lecture-tutorial-position-diagram/ 1/31: Pre Class Questions What is the SUMMER TRIANGLE? Which 3 stars does the summer triangle consist of? Indicate the source of your answer.
The Summer Triangle is made up of 3 of the brightest stars in the sky and is found in the northern celestial hemisphere The 3 stars are known as Vega, Altair, and Deneb. The triangle is at its brightest during late June through July and will appear toward the east but move overhead as the month of July passes. The triangle is not a constellation, but rather known as an asterism. An asterism is a noticeable pattern of stars. Each star of the Summer Triangle belongs to a different constellation. Vega is part of Lyra the Harp, Altair is part of Aquila the Eagle, and Deneb is part of Cygnus the Swan. https://earthsky.org/favorite-star-patterns/summer-triangle-asterism-vega-deneb-altair/ Which constellation does Regulus belong to? Explain how you found the answer and cite your source. Regulus belongs to the constellation Leo. It is one of the brightest stars in the entire sky. Regulus is often referred to as the “heart of the lion”. Regulus is at the bottom of an asterism commonly referred to as ‘The Sickle’. The sickle also looks like a backwards question mark. REgulus is visible during spring in the Northern Hemisphere. It will pass across the sky during March and April. During the month of May, it is seen in the eastern evening sky just after the sun sets and appears to have a blue-white color. An interesting fact about REgulus is it is actually 4 small stars, but to the naked eye it appears as one star. https://earthsky.org/brightest-stars/best-regulus-the-heart-of-the-lion/ Homework 4: Motion (Pearson Astronomy) (a) Note in Figure 1 that the position of Star B at 6 P.M. has been identified for you. Circle the numbered position (1, 2, 3, or 4) in Figure 2 that corresponds to the identified location of Star B at 6 P.M. provided in Figure 1. Position 3
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