Exploring the Celestial North Pole and Circumpolar Constellations

Name : Due Date : Saturday, October 28 by 11:50pm Objectives :  Learn how to use Stellarium to observe constellations  Investigate the concept of the sky’s Celestial North Pole  Observe how the stars rotate around the sky’s Celestial North Pole  Investigate the significance of the star Polaris’ relationship to the Celestial North Pole  Learn how to locate the star Polaris using the “Big Dipper”  Investigate the concept of circumpolar stars  Investigate the concept of circumpolar constellations  Determine which constellations are circumpolar from Bakersfield, Fairbanks, and Miami  Investigate how your location’s latitude affects which constellations are circumpolar Section 1.1 - How to Observe Constellations using Stellarium: In this section, you will learn how to use Stellarium to observe constellations. (1.) Make sure Stellarium ’s location is set to Bakersfield . (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 19:00 (3.) Move your view so that you are looking at the Northern horizon. You will know it’s the Northern horizon because there will be a red letter “N” on the horizon there. (4.) We now want to view the constellations. To do this, go to the bottom “horizontal menu” and click the “Constellation lines” option, which looks like: This option shows you the constellations by drawing lines between their brightest stars. Lab 4 : The Celestial North Pole and Circumpolar Constellations 1

(5.) We also want to identify these constellations by name. To do this, go to the bottom “horizontal menu” and click the “Constellation labels” option, which looks like: This option labels the constellations with their official names. Your screen should now look similar to: These options give you a good simulation of the night sky with the locations and shapes of the constellations identified. For example, you can easily use this simulation to go outside at night and find the constellations by looking at their predicted locations relative to the horizon and then identifying their brightest stars, which are connected by the lines in the simulation. (6.) A more unrealistic, but useful, way of viewing the constellations in Stellarium is to view their “artwork” images. To do this, go to the bottom “horizontal menu” and click the “Constellation art” option, which looks like: This option draws translucent images of what the constellations are supposed to be. Your screen should now look similar to: 2

Note that the shape of the connected stars in most constellations do not actually look anything like what they are named after. For example, the “triangle” shaped constellation Chamelopardelis near the Northern horizon is supposed to be a giraffe, the “W” shaped constellation Cassiopeia is supposed to be a mythological queen, and the “square and triangle” constellation Cepheus is supposed to be a mythological king. So, instead of representing the actual pattern of stars in the sky, the names and artwork of the constellations are usually just useful mnemonics that help you remember the constellations . Question 1: For the day and time you set in Step 2, which constellations are located above the Northern horizon? (Hint: If the Northern horizon is centered near the bottom of your screen, then any constellation whose name is clearly visible on your screen counts as being “above” the Northern horizon.) Ursa Minor, Ursa major, Draco, and Camelopardalis are above the Northern Horizon . Question 2: For the day and time you set in Step 2, which constellations are located above the Southern horizon? (Hint: Move your view so that the Southern Horizon’s compass point (i.e. the red letter S) is centered near the bottom of your screen. Then, any constellation whose name is clearly visible on your screen counts as being “above” the Southern horizon.) Microscopium, Indus, and Capricornus are above the southern Horizon . Question 3: For the day and time you set in Step 2, which constellations are located above the Eastern horizon? (Hint: Move your view so that the Eastern Horizon’s compass point (i.e. the 3

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red letter E) is centered near the bottom of your screen. Then, any constellation whose name is clearly visible on your screen counts as being “above” the Eastern horizon.) Cetus and Pisces are above the eastern horizon. Question 4: For the day and time you set in Step 2, which constellations are located above the Western horizon? (Hint: Move your view so that the Western Horizon’s compass point (i.e. the red letter W) is centered near the bottom of your screen. Then, any constellation whose name is clearly visible on your screen counts as being “above” the Western horizon.) Ophiuchus, and Hercules are above the western hemisphere. Question 5: For the day and time you set in Step 2, in which constellation is Saturn located? (Hint: Use the “Search window” to locate the Saturn.) Saturn would be located in the Aquarius constellation. Question 6: For the day and time you set in Step 2, in which constellation is the star Deneb located? (Hint: Use the “Search window” to locate Deneb.) The Star Deneb would be located in constellation Cygnus. (7.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 15 Time: 15:00 Question 7: For this day and time, in which constellation is the Sun located? (Hint: If you need to, use the “Search window” to locate the Sun.) The sun is in constellation Virgo. Section 2.1 - The Celestial North Pole and the Star Polaris: 4

In this section, you will investigate a special reference location in the sky called the Celestial North Pole. You will also see how this location can be easily located using the star Polaris. (1.) Make sure Stellarium ’s location is still set to Bakersfield . (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. (4.) Move your view so that the Northern horizon is centered at the bottom of your screen. (5.) Find the constellation Ursa Minor near the top of your screen. In English, this constellation name translates into “ Little Bear .” More frequently, people refer to Ursa Minor as the “ Little Dipper ,” because it vaguely looks like a small “dipping” spoon (i.e. a ladle) with a long handle. (6.) Increase the rate at which time moves by clicking the “Increase time speed” button: four times. Question 8: Which direction does the Northern sky rotate (i.e. Clockwise or Counterclockwise)? The northern sky rotates counterclockwise. (7.) You should see that the sky rotates about a special “pivot” point. This special point is called the Celestial North Pole . This point corresponds to the location in the sky directly above Earth’s North Pole spin axis. If you lived in Earth’s Southern hemisphere, you would see the Celestial South Pole above your Southern horizon, which corresponds to the location in the sky directly above Earth’s South Pole spin axis. Question 9: If you traveled to Earth’s North Pole, where would the Celestial North Pole be located in your sky (e.g. near the Northern horizon, Southern horizon, Eastern horizon, Western horizon, directly above your head, or would it not be in your sky at all)? 5

The celestial North Pole would be located directly above your head. (8.) You should see that one end of the constellation Ursa Minor touches the Celestial North Pole, and acts like a backwards spinning “hand of a clock” as it rotates about the Celestial North Pole. The star in Ursa Minor that coincidently touches the Celestial North Pole is called Polaris . Click on the star Polaris . (9.) Unlike all the other stars in the sky, Polaris essentially does not move in the sky. Instead, Polaris appears to just “hover” above the Northern compass point on your horizon, hence it is frequently called the “ North Star ”. Question 10: Propose an explanation as to why Polaris was an important star for ancient sailors and travelers. Since Polaris stays in the same position it was helpful for navigation Question 11: Why would Polaris not be a useful star for people living in Earth’s Southern hemisphere? In the southern hemisphere Polaris isn’t visible so it would not be useful Question 12: Some people think that because the “North Star” is a special star, it must be unusually bright. Compared to the other stars in the sky, is the “North Star” unusually bright or is it roughly average in brightness? The North Star is averagely bright sitting at 48 th brightest. Section 2.2 - Finding Polaris using the “Big Dipper”: In this section, you will learn a famous method for finding the star Polaris (and hence the Celestial North Pole and the North compass point) using the “Big Dipper” component of the constellation Ursa Major. (1.) Make sure Stellarium ’s location is still set to Bakersfield . (2.) Use the “Date/Time window”: 6

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to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. (4.) While facing North, move your view to the left so that you see the large constellation Ursa Major . In English, this constellation name translates into “ Big Bear .” More frequently, people usually just refer to the “backend and tail” of the Big Bear, and call it the “ Big Dipper .” This name is used because, like the “Little Dipper,” the “Big Dipper” vaguely looks like a large “dipping” spoon that has a long handle. (5.) The “Big Dipper” is a very useful reference location in the sky because its stars are bright and easy to see. In order to find the “Big Dipper,” all you have to do is go outside and scan the Northern sky and you should easily find it if your sky is at least mildly dark. The “Big Dipper” component of the Big Bear constellation is highlighted in the picture below. (6.) Click each of the seven stars in the “Big Dipper” and record their names and distances away from Earth in Table 1 below. This name and distance information is provided within the upper- left corner of your screen when you click on a star. The information for “Star A” has been filled in as an example. Note that the “Star Labels” A through G refer to the letters they are labeled as within the picture of the “Big Dipper” above. 7

Table 1 Star Label Star’s Name Distance from Earth (Light Years) A Alkaid 103.94 B Mizar 85.81 C Alioth 82.55 D Megrez 80.51 E Phecda 83.18 F Merak 79.75 G Dubhe 122.89 Question 13: Are the stars of the “Big Dipper” located the same distance away from Earth? No, the stars are located at different distances. Question 14: Based on your answer to the question above, do you think the stars in the “Big Dipper” are physically related to each other in space? (Hint: If they are related, they would have to be very close together.) No, I don’t think the stars are related since they all aren’t very close together. (7.) Of the many celestial navigational uses that the “Big Dipper” can be used for, it most famously can be used to easily find the star Polaris. To find Polaris using the “Big Dipper,” you use its two “Pointer Stars” (labeled as stars F and G in the picture above) to point your way to Polaris. This technique for finding Polaris is shown in the picture below. 8

Section 3.1 - Circumpolar Stars and Circumpolar Constellations: In this section, you will investigate the concepts of circumpolar stars and circumpolar constellations. (1.) Make sure Stellarium ’s location is still set to Bakersfield . (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. 9

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(4.) Move your view so that the Northern horizon is centered at the bottom of your screen. (5.) Increase the rate at which time moves by clicking the “Increase time speed” button: four times. (6.) As the sky rotates, note that some of the stars around Polaris and the Celestial North Pole never rise above the horizon or set below the horizon. These stars are called circumpolar stars because all they do is circumnavigate around the Celestial North Pole like a “Ferris Wheel” and never rise above or set below the horizon . Question 15: Based on the definition of a circumpolar star, are circumpolar stars technically still in your sky during the daylight hours? Yes, circumpolar stars would still be in the sky since they never set or Rise above or below horizon Question 16: Based on the definition of a circumpolar star, how many hours of day light would you have if the Sun was a circumpolar star? If the sun was a circumpolar star, we would have 24 hours of daylight. (7.) While the Stellarium sky continues to rotate, use the “Search window” to find the Stars in Table 2 below and identify if the stars are circumpolar or not circumpolar. Table 2 Star Name Is the Star Circumpolar? (Yes / No) Vega Yes Altair Yes Dubhe Yes Antares Yes Algol Yes Errai Yes Caph Yes 10

(8.) Constellations that are at least 50% composed of circumpolar stars are called circumpolar constellations . For example, you should see that 100% of the stars in Ursa Minor are circumpolar stars, so Ursa Minor is a circumpolar constellation in your sky. Meanwhile, about 50% of the stars in the constellation Ursa Major are circumpolar, so Ursa Major is also a circumpolar constellation. (9.) While the Stellarium sky continues to rotate, use the “Search window” to find the Constellations in Table 3 below and identify if the constellations are circumpolar or not circumpolar. Table 3 Constellation Name Is the Constellation Circumpolar? (Yes / No) Lyra No Cygnus No Cepheus Yes Draco Yes Sagittarius No Hercules No Scorpius No Section 3.2 - Which Constellations are Circumpolar from Bakersfield?: In this section, you will determine which constellations are circumpolar as seen from the middle-latitude city of Bakersfield. (1.) Make sure Stellarium ’s location is still set to Bakersfield . (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. 11

(4.) Move your view so that the Northern horizon is centered at the bottom of your screen. (5.) Increase the rate at which time moves by clicking the “Increase time speed” button: four times. Question 17: As viewed from Bakersfield, which constellations are circumpolar constellations? (Hint: You should identify about 6 constellations. ) Draco Cepheus Ursa Minor Camelopardalis Ursa major Cassiopeia Section 3.3 - Which Constellations are Circumpolar from Fairbanks, Alaska?: In this section, you will determine which constellations are circumpolar as seen from the high-latitude city of Fairbanks, Alaska. (1.) Click the “Location window” button: and set Stellarium ’s location to Fairbanks . It will show up in Stellarium ’s city database list as “Fairbanks, Northern America.” If you do not remember how to change locations, see Lab 2. (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. 12

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(4.) Move your view so that the Northern horizon is centered at the bottom of your screen. (5.) Increase the rate at which time moves by clicking the “Increase time speed” button: four times. Question 18: As compared to Bakersfield’s sky, are Polaris and the North Celestial Pole located higher above the Northern horizon or lower above the Northern horizon as viewed from Fairbanks? Polaris is a lot lower in the northern horizon as opposed to the Fairbanks sky it is a not higher in the northern horizon. Question 19: As viewed from Fairbanks, which constellations are circumpolar constellations? (Hint: You should be able to identify about 20 constellations, but it’s okay if you only list 15 of them.) Ursa Major Ursa Minor Draco Cepheus Cassiopeia Camelopardis Deneb Algol Capella Pollux Vega Kochab Yildun Altais Merak Mizar Alioth Question 20: Why do you see more circumpolar constellations when Polaris and the North Celestial Pole are located higher above your Northern horizon? 13

The farther you go North the more stars are circumpolar. Also, Polaris Shines at zenith so from the North Pole every star in the sky stays above the horizon all day long every day of the year. Section 3.4 - Which Constellations are Circumpolar from Miami, Florida?: In this section, you will determine which constellations are circumpolar as seen from the low-latitude city of Miami, Florida. (1.) Click the “Location window” button: and set Stellarium ’s location to Miami . It will show up in Stellarium ’s city database list as “Miami, Northern America.” If you do not remember how to change locations, see Lab 2. (2.) Use the “Date/Time window”: to set the day and time to: Day: 2023 / 10 / 31 Time: 3:30 (3.) We still want to see the constellations, so keep the “Constellation lines,” “Constellation labels,” “Constellation art” options: turned on. (4.) Move your view so that the Northern horizon is centered at the bottom of your screen. (5.) Increase the rate at which time moves by clicking the “Increase time speed” button: four times. Question 21: As compared to Bakersfield’s sky, are Polaris and the North Celestial Pole located higher above the Northern horizon or lower above the Northern horizon as viewed from Miami? As compared to Bakersfield Polaris and the North celestial pole are located a lot lower than Polaris in Bakersfield. 14

Question 22: As viewed from Miami, which constellations are circumpolar constellations? (Hint: You should be able to identify about 4 constellations.) Camelopardalis Ursa Minor Ursa Major Draco . Question 23: Why do you see fewer circumpolar constellations when Polaris and the North Celestial Pole are located lower above your Northern horizon? You see fewer constellations because there is less space above the horizon for them to be visible. The more space between Polaris and the horizon the more constellations will be visible. Question 24: Note that Miami is a low-latitude city (i.e. it’s near Earth’s equator), Bakersfield is a middle-latitude city (i.e. it’s roughly midway between Earth’s equator and Earth’s North pole), and Fairbanks is a high-latitude city (i.e. it’s near Earth North pole). Using this latitude information and the number of circumpolar constellations you found this for each city, explain how your latitude affects the number of circumpolar constellations you see in your sky. Your latitude determines your circle of circumpolar Stars. This means that depending on how high or how low the city’s latitude is will determine the number of circumpolar stars. A high latitude city will have more circumpolar stars since it is closer to earth’s North Pole. Section 4.1 - How to Submit Your Finished Lab Document : Be sure to type your full name inside the box located at the top of page 1. When you have finished, save this lab document with your last name and first name added to the beginning of the filename. For example, this lab document originally has the filename: LASTNAME_FIRSTNAME_Lab04 and you should resave your finished lab document with your last name and first name replacing the words “LASTNAME” and “FIRSTNAME” . For example, I would resave my finished lab document as CAMERON_SCOTT_Lab04. Once you have your completed lab document renamed, you need to submit it to our class website for it to be graded. To submit your completed lab document to the class website, go to the: 15

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“Submit Your Finished Lab 4 Document Here” link that is available under the correct week’s “Lab: ” assignment section. From there, you’ll submit the lab document to the webpage by first clicking the “Add Submission” button near right hand corner of the page. 16

_Lab04 copy

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