Two models to explain Moon phases

Two models to explain" rel="nofollow">in Moon phases Oftentimes in" rel="nofollow">in science, more than one “model” or explanation for a natural phenomenon can be imagin" rel="nofollow">ined. In these cases, scientists devise testable predictions of the various models. Then scientists conduct experiments or observations of nature to see which predictions are most closely borne out. The model whose predictions are best borne out in" rel="nofollow">in nature is then considered most likely to be correct. (Of course, it is possible that none of the imagin" rel="nofollow">ined models is correct. In this case, scientists must scratch their heads and thin" rel="nofollow">ink of yet new models.) For example, consider the cause of phases of the Moon. When most people are asked about phases of the Moon, they offer one of two explanations or “models”. 1. Moon phases are caused by the shadow of the Earth on the Moon – Accordin" rel="nofollow">ing to this model, the Earth casts its shadow on the Moon. At different times, the Earth’s shadow covers more or less of the Moon, thus accountin" rel="nofollow">ing for the different phases of the Moon. 2. Moon phases are caused by different angles between the Moon, Earth and Sun – Accordin" rel="nofollow">ing to this model, the angle between the Moon and Sun changes over time. As a result, we see different fractions of the Moon’s illumin" rel="nofollow">inated hemisphere at different times, thus accountin" rel="nofollow">ing for the different phases of the Moon. Recall that a model in" rel="nofollow">in science is a conceptual description of some phenomenon in" rel="nofollow">in nature. (For example, we talked about the “celestial sphere” model in" rel="nofollow">in class, even though we know that this particular model is not literally correct.) In this in" rel="nofollow">inquiry project, you will be asked to develop testable predictions for each of the two Moon phase models above. Then you will be asked to gather data, as described below, and test your predictions to determin" rel="nofollow">ine which model best fits your predictions. In so doin" rel="nofollow">ing, you will be learnin" rel="nofollow">ing about how science works. • An example of a model and a testable prediction – Suppose this project were about seasons. Then your model might be as follows: “The Earth goes around the Sun in" rel="nofollow">in an elongated orbit, causin" rel="nofollow">ing the distance between the Earth and Sun to vary significantly durin" rel="nofollow">ing the year. This yearly variation in" rel="nofollow">in Earth-Sun distance causes seasonal variations in" rel="nofollow">in temperature on the Earth.” A testable prediction might be as follows: “Everywhere on Earth, temperatures should be highest on about the same date of the year, namely the date when the Earth is closest to the Sun. Therefore, summer should take place all over the Earth at around the same time of year.” Note that this particular model is false. Nonetheless, if the project were about seasons, you could gather temperature data throughout the year for various locations on Earth (Northern and Southern Hemispheres), compare these data with your prediction, and in" rel="nofollow">infer that the model is false. Then you would try to create another model about seasons for which the testable predictions were verified by the data. AST Inquiry Project Ready? Please follow steps 1-5 below. Don’t worry if everythin" rel="nofollow">ing is not 100% clear to you, especially when you first read these steps. Thin" rel="nofollow">ings are rarely 100% clear in" rel="nofollow">in science, especially at the begin" rel="nofollow">innin" rel="nofollow">ing of an in" rel="nofollow">investigation. 1. Develop testable predictions for the moon phase models Thin" rel="nofollow">ink about testable predictions for Moon phases, based on the two Moon phase models listed above. By comparin" rel="nofollow">ing your predictions with naked eye Moon observations and, especially, with web data on Moon phases, you can argue which model above is correct. Of course, you may already know which model is correct. If so, good for you! Nonetheless, you are asked in" rel="nofollow">in this in" rel="nofollow">inquiry project to clearly demonstrate why you thin" rel="nofollow">ink one Moon phase model is correct and the other is in" rel="nofollow">incorrect. To help you develop testable hypotheses for both models, recall that the Moon orbits the Earth in" rel="nofollow">in about one month’s time. Then consider these questions: • If Moon phases are caused by the shadow of the Earth on the Moon (model 1), where do you predict the Moon should lie in" rel="nofollow">in its orbit when the Moon is new? (It might help you to make a simple drawin" rel="nofollow">ing of the Earth, the Moon’s orbit about the Earth, and the Sun off to one side. Your drawin" rel="nofollow">ing need not be to scale.) What will be the angle between the Sun and the Moon in" rel="nofollow">in the sky at new Moon? Note that new Moon is the phase in" rel="nofollow">in which all of the Moon’s face is dark in" rel="nofollow">in our Earthly sky. So in" rel="nofollow">in model 1, the Moon must be entirely in" rel="nofollow">in the shadow of the Earth. • If Moon phases are caused by the shadow of the Earth on the Moon (model 1), is the Moon full for most of the lunar month, for part (say, about half) of the lunar month, or for only a small fraction of the lunar month (say, a day)? • If Moon phases are caused by different angles between the Moon and Sun (model 2), then how should the illumin" rel="nofollow">inated fraction of the Moon’s face be related to the angle between the Sun and the Moon in" rel="nofollow">in the sky? For example, when half of the Moon’s illumin" rel="nofollow">inated hemisphere is visible from Earth (“half moon” in" rel="nofollow">in popular language), what should the angle be between the Sun and Moon in" rel="nofollow">in the sky? • If Moon phases are caused by different angles between the Moon and Sun (model 2), is the Moon full for most of the lunar month, for part (say, about half) of the lunar month or for only a small fraction of the lunar month? To Do - Usin" rel="nofollow">ing the questions above and/or your own ideas, develop two testable predictions for each of models 1 and 2. You should briefly explain" rel="nofollow">in your reasonin" rel="nofollow">ing for each of these testable hypotheses. 2. Make naked eye observations of Moon phases in" rel="nofollow">in the sky • How many Moon phase observations to make - You are asked to observe the phase of the Moon in" rel="nofollow">in the sky on at least four days over a roughly two week period. However, more observations over a longer period are encouraged if your schedule and the weather permit. • What in" rel="nofollow">information to record - For each Moon observation, you should record the followin" rel="nofollow">ing in" rel="nofollow">information: (a) the date of your observation; (b) the time of your observation, Eastern Standard Time, 24 hour clock; (c) the location of your observation (e.g. “outside The Nin" rel="nofollow">inety”, or “outside my apartment on Woodland Avenue”); (d) the approximate per cent of the Moon’s round disk that is illumin" rel="nofollow">inated (e.g. 10%, 50%, 100%, where 100% means full moon); and (e) the elevation angle of the Moon above the level horizontal horizon in" rel="nofollow">in degrees. (See measurement in" rel="nofollow">instructions immediately below.) Note that your Moon observations need not all be made from the same location. • How to measure the elevation angle of the Moon above the level horizon – Hold your fist vertically at arm's length so that the bottom of your fist is level with your eye. Do not extend your thumb. Estimate how many fists fit between the level horizon and the Moon in" rel="nofollow">in the sky. Each fist is about 10 degrees of angle. So if the Moon is about 2 fists above the level horizon, the elevation is 20 degrees. Of course, this method of measurin" rel="nofollow">ing Moon elevation is not particularly accurate. Therefore, do not try to measure the Moon elevation to better accuracy than a half a fist width (i.e. 5 degrees). Note - The level horizon extends horizontally away from you in" rel="nofollow">into the distance. If you were on a ship at sea, the actual horizon would be the level horizon. In practice, the level horizon is usually blocked in" rel="nofollow">in Lexin" rel="nofollow">ington and elsewhere by buildin" rel="nofollow">ings and trees. Nonetheless, you can estimate the location of the level horizon by placin" rel="nofollow">ing the bottom of your fist level with your eye, as described above. • A Microsoft Excel spreadsheet file to help you record in" rel="nofollow">information – To help you record your in" rel="nofollow">information and in" rel="nofollow">include the in" rel="nofollow">information as a table in" rel="nofollow">in your report, you may wish to download the Microsoft Excel spreadsheet file Moon Phases Data AST191 S17.xls. You can record your observations in" rel="nofollow">in the Excel worksheet Observations of the Moon. Note the comments in" rel="nofollow">in the top row of the worksheet. To download this file from Canvas, choose Files in" rel="nofollow">in the menu on the left side of the course homepage. Click on the filename, then choose Download. • Useful Hin" rel="nofollow">ints – Observations will be conveniently possible in" rel="nofollow">in the late afternoon and/or early evenin" rel="nofollow">ing if you begin" rel="nofollow">in observin" rel="nofollow">ing on about Thursday, March 30, weather permittin" rel="nofollow">ing. (On that date, avoid black cats while observin" rel="nofollow">ing the Moon!) Observations of the Moon do not necessarily have to be made at nighttime! The Moon is frequently visible in" rel="nofollow">in broad daylight. For example, go outside on a clear day in" rel="nofollow">in the late afternoon in" rel="nofollow">in the approximate time frame April 1-5, 2017. You will fin" rel="nofollow">ind the Moon visible rather high in" rel="nofollow">in the sky durin" rel="nofollow">ing the daytime. 3. Gather Moon phase data from a website • Where to fin" rel="nofollow">ind Moon data on the in" rel="nofollow">internet - Information about the Moon is available at the U.S. Naval Observatory website http://aa.usno.navy.mil/data/. Go to this site and choose Complete Sun and Moon Data for One Day near the top of the webpage. Insert the requested in" rel="nofollow">information in" rel="nofollow">into Form A – U.S. Cities or Towns on the webpage, and then click on Get data to see the results for a specified location and date. Chose Lexin" rel="nofollow">ington Kentucky as your location. Important note - You can generate a table of moonrise & moonset times and a separate table of sunrise & sunset times for all dates in" rel="nofollow">in 2017. To do so, go back to the homepage designated above and click on Table of Sunrise/Sunset, Moonrise/Moonset… Again" rel="nofollow">in specify Lexin" rel="nofollow">ington, Kentucky. Then choose Type of table, then Compute Table. • What in" rel="nofollow">information to record from the website - Gather data for every other day over a period of a month (that is, data for about 15 different days, spannin" rel="nofollow">ing a total period of about 30 days). If your last name begin" rel="nofollow">ins with “A”, begin" rel="nofollow">in gatherin" rel="nofollow">ing web data for April 1, 2017. (So you will gather data for April 1, 3, 5…) If your last name begin" rel="nofollow">ins with “B”, begin" rel="nofollow">in gatherin" rel="nofollow">ing web data for April 2, 2017. (So you will gather data for April 2, 4, 6…) And so on. If your last name begin" rel="nofollow">ins with Z, begin" rel="nofollow">in gatherin" rel="nofollow">ing web data for April 26, 2017. (So you will gather data for April 26, 28, 30…) For each day that you choose, record the followin" rel="nofollow">ing in" rel="nofollow">information in" rel="nofollow">in a table: (a) date; (b) time of moonrise for that day, Eastern Standard Time (EST), 24 hour clock; (c) phase of the Moon, e.g. waxin" rel="nofollow">ing crescent; (d) per cent of the Moon’s visible disk illumin" rel="nofollow">inated, and (e) time of sunrise. If you wish, you may record your data in" rel="nofollow">in the spreadsheet file Moon Phases Data AST 191 S17.xls, worksheet Moon data from website. Note the comments in" rel="nofollow">in the top row of the worksheet. When enterin" rel="nofollow">ing times of moonrise and times of sunrise, take the in" rel="nofollow">information from the tables of moonrise/moonset and sunrise/sunset described in" rel="nofollow">in the bulleted item immediately above. For some dates (e.g. April 16, 2017), the moon does not rise in" rel="nofollow">in the 24 hour period of that day. For these dates, leave your moonrise entry in" rel="nofollow">in the table blank. 4. Analyze and in" rel="nofollow">interpret your data for Moon phases • Connections among the data you have gathered - Consider the data you have gathered from the in" rel="nofollow">internet about time of moonrise, time of sunrise, phase of the Moon and the per cent of the Moon’s visible disk illumin" rel="nofollow">inated. What connections can you fin" rel="nofollow">ind among these data? Consider, for example, the differences in" rel="nofollow">in times between sunrise and moonrise for the 15 or so days. (You should calculate the differences in" rel="nofollow">in these times. Take, for example, the time of moonrise min" rel="nofollow">inus the time of sunrise.) How are these time differences related to other data about Moon phases? If you are reasonably familiar with Microsoft Excel, you may want to make a graph or two of the moonrise – sunrise time differences versus other data on Moon phases. • Comparison of the data with the Moon phase models and your testable predictions – How well are your testable predictions for the two Moon phase models borne out by the data you have gathered (data from observations of Moon phases in" rel="nofollow">in the sky and, especially, data from the in" rel="nofollow">internet)? Which Moon phase model is more consistent with your predictions and why? If you had more time to complete this project, what additional data might you have used to further test your model’s predictions? 5. Write your report and submit to Canvas by Monday, April 24, 2017 • What to put in" rel="nofollow">in your report - Your report should consist of each of the four sections outlin" rel="nofollow">ined below. The credit to be assigned to each section is also listed. The in" rel="nofollow">instructor envisions that reports on this project would typically be about 5-6 pages long, in" rel="nofollow">includin" rel="nofollow">ing tables. However, grades for the report will be based solely upon how well you follow the in" rel="nofollow">instructions for the project and carry out the requested data analysis, not upon the length of the report. If you submit a shorter but thoughtful report that covers the important elements of this project, you will receive full credit. Of course, there is no penalty for submittin" rel="nofollow">ing a somewhat longer report. • How to submit your Inquiry Project report to Canvas - Your report must be submitted to the course Canvas site in" rel="nofollow">in the format of a sin" rel="nofollow">ingle pdf file. If you do not know how to create a sin" rel="nofollow">ingle pdf file, please consult on-lin" rel="nofollow">ine help or ask a friend. To submit your report, choose Assignments in" rel="nofollow">in the Canvas menu on the left side of the course homepage. Then choose the Inquiry Project assignment. Click on Submit Assignment, upload your pdf file, and then click on Submit Assignment again" rel="nofollow">in. Report sections (12% total credit) 1. Testable predictions for the two models (4%) – You should thin" rel="nofollow">ink of at least two testable predictions for each model of Moon phases described earlier in" rel="nofollow">in this document. Briefly explain" rel="nofollow">in your reasonin" rel="nofollow">ing for the predictions. 2. Information about your observations of actual Moon phases in" rel="nofollow">in the sky (2%) - This in" rel="nofollow">information can be provided in" rel="nofollow">in table form, extracted, if you like, from the Excel spreadsheet file you may have used to record your in" rel="nofollow">information. You should in" rel="nofollow">include a brief text describin" rel="nofollow">ing your table. 3. Data from the website on moonrise, sunrise, etc. for every other day over a period of a month (2%) - These data, too, should be given in" rel="nofollow">in table form, extracted, if you like, from the Excel spreadsheet file you may have used to record your in" rel="nofollow">information. Again" rel="nofollow">in, in" rel="nofollow">include a brief text describin" rel="nofollow">ing your table. 4. Analysis of the data (4%) – Discuss the questions outlin" rel="nofollow">ined above in" rel="nofollow">in the section above Analyze and in" rel="nofollow">interpret data for Moon phases. Possible bonus credit! Students who follow the in" rel="nofollow">instructions above with reasonable attention are quite likely to receive full credit for this project. However, students who show evidence of additional effort in" rel="nofollow">in data collection and, especially, in" rel="nofollow">in data analysis and in" rel="nofollow">interpretation are eligible for up to 3% of bonus credit