Lab4_Navigating_the_stars.docx

Name : Eric Chung Lab N o :4________ Partner(s) _________________ Date : 2/23/2023 NAVIGATING THE STAR USING A STAR CHART & CELESTIAL SPHERE Activity 1: Navigating the star using a star chart (or planisphere) 1- How do you know if a particular star or constellation (group of stars) will be up in the sky on a certain night? Use a star chart if available. If not, map each night and day for one year to understand when each star or constellation will re-appear. A star chart is a simple device that allows you to determine which stars or constellations are visible at particular times of the evening. The rising and setting times of stars and constellations can be determined. Use the star chart (picture of the star chart is available below for the students who do not have it) to answer the following questions: 2- Label north, south, east, and west on THE NIGHT SKY to the picture below as they appear on the star chart. Are east and west in the positions you expect with respect to the north? Explain. No, I expected them to be switched since East is usually to the right of North (when you look at it upside down). This is a picture of a star chart, this is useful for those students who do not have a star chart. 1

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You label this night sky. Label North, South, East, West, Polaris and Zenith. If you have difficulty to label it, just describe the position of the label with the text below. 3- Hold the star chart over your head with north on the chart pointing to the north. Are east and west where you expect them? No, they are not. They are switched. 4- What does this mean about how you are expected to use the star chart? You must hold it over your head so that your sight aligns with the compass. That way you will know precisely where the stars will appear in the sky. 5- What part of the star chart defines the horizons? These are your limits of viewing. The part of the star chart where the cardinal directions North, East, and West arelabeled defines the horizon. 6- Locate and label the position of Polaris, the North Star, on THE NIGHT SKY above. What is important about this point? Polaris is named the North Star because it points North regardless of your positioning on Earth. 3

7- Where is the zenith on the star chart? Label it on THE NIGHT SKY above. South 8- Will you expect the pattern and position of constellations on the star chart to exactly match the display you will see in the sky? Explain why or why not. I would expect it to be accurate if I was in the 30 o -40 o north latitude area, as that is specifically what the star chart says it’s for. If I wasn’t, this would not be accurate at all. 9- The star chart is set to work in a range of latitudes. The chart you are using is exact at 40 o N latitude (or 30-40 o N), which is the latitude of Maryland’s northern border. From the “north” mark on the star chart, determine the number of degrees between the horizon and Polaris. Around 32 between the horizon and Polaris. 10-How is this related to the latitude where the star chart is exact? The latitude of a specific location is equivalent to the number of degrees between the north horizon and Polaris. Consequently, if that latitude is between 30 o and 40 o , the star chart will be accurate. 11-In Bowie (Maryland) the latitude is approximately 39 o N. How far above the northern horizon would you expect to find Polaris? Around 39 o above the horizon 12-If you were at the north pole of the Earth, would this star chart give you an accurate representation of the night sky? Why or why not? It doesn’t work because the North Pole is art a different latitude. 13-Set the chart for 15 December at 9:00 pm by holding the stationary portion of the chart, turning the sky dial until your time of night lines up with the observing date. Any object in the oval opening is visible at the position for the date and time. (Please use the setting above, first picture. This also serves as the star chart for those students who do not have it). Use this setting to answer the following questions. 4

a- Find the constellation Pegasus. In which direction in the sky would you look to find it? West b- Locate and list a constellation that is rising. Cancer c- Locate and list a setting constellation. Aquarius d- What constellation is at your zenith? Eridanus e- Find the constellation Orion. What is the declination or location of Orion's belt? East f- Sirius is the brightest star in the night sky. In which constellation is the star Sirius? Canis Major g- What are the declination and right ascension of Sirius? Right ascension = 6hr 45m Declination = -15 h- At what time will Sirius rise? 6:30 am i- At what time will Sirius set? 8 pm 5

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