AST201L.Lab11.Word

NAME & USERNAME: TRENT FREEMAN SECTION: 07 LAB11-1 LAB 11 STARS AND TIME INTRODUCTION This entire lab requires outdoor observing of the night sky. This lab focuses on the diurnal movement of stars in the night sky as they circle around the North Celestial Pole. You will learn to identify prominent stars and constellations in the early part of the winter night sky and to track their movement. You will also estimate angular distances in the sky using your hands at arm ’ s length. Recall the helpful apps and websites ( i.e., Stellarium ) from Lab 1 that you might want to use to help you in this lab. In this lab, you will learn about the Navajo, or Diné, Constellations, and their stories. In Diné culture, these stories, as well as the Origin Story, are part of their Winter Stories, which are only proper to tell during winter time, from the first snow to the first lightning (roughly September to March) . Please remember that this lab is taught at this time (if outside of Sep. to Mar.) only for educational purposes. Let us respect Diné culture and history together, and learn how Diné people seek harmony with the sky and nature. LEARNING GOALS The points below are the expected topics to understand by the end of this lab period. Remember to review these points before completing the lab. If you do not understand one, review the steps that cover it and discuss with your instructor. • Learn to identify and name constellations • Learn to measure angles on the night sky • Learn three important Navajo constellations and their significance in the night sky O U T D O O R S K Y - W A T C H I N G E X E R C I S E

NAME & USERNAME: TRENT FREEMAN SECTION: 07 LAB11-2 STEP 1: FINDING NÁHOOKÒS CONSTELLATIONS To get started, find a place where you have a relatively clear, dark view of the night sky. Face north, approximately in the direction of the San Francisco Peaks. If it is early evening in winter, the Big Dipper will appear low in the sky to your left (towards the West). The North Star (Polaris) is at the end of the handle of the Little Dipper. The Little Dipper is more difficult to see in general, since many of its stars are faint. The Big Dipper, however, is much more recognizable, and two “ pointer stars” at the end of the cup point to the North Star as shown in Figure 7.1. The Navajo interpretation of the Big Dipper is the “ Male Revolving One” or Náhookòs Bi ’ k à’ ii (pronounced Na Hoe kos bi kah ee – Practice pronouncing this and point it out to someone else if you get the chance!). To the Navajo, Náhookòs Bi ’ k à’ ii is a male warrior and leader who protects his people and is pictured as lying on his side. He is sympathetic, charismatic, and a provider for his family and home. As a father, he provides spiritual and physical protection, and he is always paired with his female counterpart Náhookòs Bi ’áá dii (pronounced Na hoe kos Bih aad ee – more below). The North Star is known to the Navajo as the “ Central Fire ” or Náhookòs Bik ò‘ (pronounced Na hoe kos Bih kwo) and symbolizes the central hearth in a Navajo Hogan. Describe your location here (city, location in the city, coordinates if you have them): Flagstaff, west-central part of town, 35 N, 111 W. Figure 7.1: The Big Dipper, Cassiopeia, the North Star (Polaris) and the Little Dipper as seen in early winter evening in the Northern Hemisphere at mid-latitudes. The two stars at the end of the cup in the dipper are known as the “ pointer stars ” because they point to the North Star. Their names in Western astronomy are Merak (farthest from the North Star) and Dubhe (closer to North Star). On the other side of the Big Dipper, you can see Cassiopeia. The brightest star in Cassiopeia is Shedar, and the neighbor stars are called Caph and Cih (or Navi). Figure 7.2: The size and distances between objects in the sky are typically given as a measure of their angular distance as seen from Earth. These distances are measured in degrees. A circumference is equal to 360°; one degree is 1/360; one arcminute is 1/60 of 1°, and one arcsecond is 1/60 of 1 arcminute (or 1/3600 of 1°). To put this in perspective, the Moon has an angular size of 0.5°, or 30 arcminutes (which is the same as 1,800 arcseconds).

NAME & USERNAME: TRENT FREEMAN SECTION: 07 LAB11-4 As you may recall, if you were at the North Pole, Náhookòs Bikò ‘ would be directly overhead, or approximately 90 degrees in altitude above the Horizon. Not coincidentally, your latitude would also be 90 degrees north. If you were at the Equator, your latitude would be 0 degrees, and Náhookòs Bikò ‘ would be at 0 degrees altitude from the horizon. The altitude of the North Celestial Pole is the same as your latitude in degrees in the northern hemisphere. Use this fact to estimate your latitude by using your fist to measure the angular separation between the horizon and Náhookòs Bikò ‘ .Note that you need a clear view to the northern horizon for this to work, or you need to estimate accurately where that horizon line actually is by starting your fist measurements with your arm exactly level to the horizontal direction directly below the North Star and then counting fists vertically to the North Star. The official latitude of Flagstaff, AZ is 35° N. 1. What is your estimate of Altitude of Náhookòs Bikò ‘ in degrees? [0.5pt] Roughly 35 degrees 2. What is your Geographic Latitude of observation? You can put a pin on Google Map and it will tell you your Latitude. [0.5pt] 70 degrees N 3. How do these two numbers compare? And what does it say about the uncertainty in your estimate? Give a brief explanation and discuss the numerical quantities explicitly if you can. [1pt] About twice in the northern direction STEP 4: NÁHOOKÒS BI’ÁÁDII The Western Constellation Cassiopeia is often identified as a wide “ W ” formed by its brightest stars (see Figure 7.1). It is located on the other side of Náhookòs Bik ò‘ (North Star) from Náhookòs Bi ’ k à’ ii (Big Dipper) and lies in the Milky Way. This “ W ” forms part of the Navajo Constellation “ Revolving Woman” or Náhookòs Bi ’áá dii. Find this constellation in the evening sky by looking to the upper left of Náhookòs Bik ò‘ opposite the North Star. You can also use your app to find the constellation. Náhookòs Bi ’áá dii is a woman who exemplifies motherhood and regeneration. She provides growth, stability in the home and the strength necessary for harmony. Instead of a bow and arrow, her weapons are her grinding stone and stirring sticks, which ensure that she will always be able to feed her family. The brightest star of Cassiopeia is Shedar (see Figure 7.1) and it is furthest from the North Star. Use your middle fingers to estimate the angular distance between Shedar and its neighbors Caph and Cih (or Navi). 1. What is the angular separation between Shedar and Caph in degrees? [1pt] About 13 degrees 2. What is the angular separation between Shedar and Cih in degrees? [1pt] 17 degrees 3. Now find the angular separation between Shedar and Náhookòs Bik ‘ò in degrees. [1pt] About 50ish degrees Stars with angular separations from Náhookòs Bik ò‘ that are less than its altitude above the horizon at a particular latitude will never set! They are said to be circumpolar and will continue to revolve around Náhookòs Bik ò‘ .

NAME & USERNAME: TRENT FREEMAN SECTION: 07 LAB11-5 4. Given your observations above, are either Merak or Shedar circumpolar? Explain your reasoning in a few sentences. [1pt] Merak is not likely to be a circumpolar star, although Shedar is. This is due to the fact that Shedar is closer to the celestial pole than Merak. As a result, for observers at a given latitude, Shedar never sets below the horizon, but Merak rises and sets. 5. Why might the Navajo refer to these constellations as “ Revolving Man” and “ Revolving Woman?” Explain in a few sentences. [1pt] The titles "Revolving Man" and "Revolving Woman" represent the Navajo idea that men and women are complimentary energies that must coexist in order for society to be balanced and peaceful. The two constellations are also said to represent the never-ending cycle of life, death, and rebirth. 6. [BONUS] If you have time, continue to watch these two constellations off and on for a period of about 2 hours. Which direction do they circle in (clockwise or counterclockwise) and approximate how much of a full circle do they move through in this amount of time? You may use the online Stellarium website to do parts of this Lab: stellarium-web.org, if the sky is cloudy all week long. Turn on the Azimuthal Grid in Stellarium to estimate the angular distances for questions in the lab. Please note on your lab if you do it this way, and contact your instructor directly. A L T E R N A T I V E S T O O B S E R V A T I O N S