GEK1506 Heavenly Mathematics & Cultural Astronomy, Moon Homework

Goals of the Homework

There are four goals of the Moon homework.

• Determine the day of the first visibility of the lunar crescent, i.e., the first day of the Muslim month
• Determine the day of the first daytime visibility of the Moon
• Determine the tilt of the Moon when it is a crescent close to the horizon
• Follow the phases of the Moon in the course of a lunar month

Small crescent in the top middle: Second day of the Chinese month, first day of the Muslim month

Details of the Homework

I want you to take seven photos of the Moon in the course of a lunar month.

• I want photos of the Moon on each of the first three days of the Chinese lunar month that starts after September 1 or February 22. (I don't want to ruin Chinese New Year for you!) However, if the new Moon occurs after sunset on the first day, I want pictures of day two through four. If we have an evening lecture, we will either skip the picture if we are not likely to see the Moon, or take a "field trip" to take pictures. (In 2008 Chinese New Year is on February 7. Please take photos of the first three days of the lunation starting with the new Moon on March 8.)
• I want a picture of the Moon on the first day it is visible during daytime (before sunset). I do not know which day this will be. You may have to try several days.
• I want one photo each from around the first quarter, around the full Moon and around the third quarter. Most semesters I want all pictures to be of the same lunar month, but some semesters this doesn't work. (In 2008 Chinese New Year is on February 7. Please start your observations with the full Moon of that lunation, and finish with the first quarter of the lunation starting on March 8.)
• For each observation include the following.
  1. Photo of the Moon. For the three crescents I want a photo showing the horizon and the Moon. (Or a building or something else that indicates where the horizon is.) If the Moon is not easily visible in the horizon picture, please also include a zoomed in photo of the Moon.
  2. Time of the photo.
  3. Age of the Moon by indicating the day of the month in either the Chinese, Islamic calendar or an Indian lunisolar calendar. (But please don't use an Indian solar calendar!)
  4. Approximate azimuth using a compass.
  5. Approximate altitude using your hand as described in the links at the bottom of the page.
  6. For the three crescent Moons close to the horizon, use a protractor to measure the approximate tilt of the Moon. By the tilt I mean the angle between the line between the two "horns" and the horizon. Discuss briefly whether the angle of the tilt matches the theory.
  7. Time of sunrise, sunset, moonrise and moonset for that day.

You will be graded on the clarity of your presentation. The pictures must clearly illustrate the concepts and confirm that you made the observations.

Please do this in your project groups and submit both soft copy and hard copy.

These links give info about the Moon.

More Details of the Homework

• You may not be able to see the Moon because of the weather. In that case I'm afraid you'll have to try again the next day. The only exceptions are the three waxing crescents. You are not expected to see all of them, and with bad weather, you may not see any of them. What I want for those, are pictures of the Western horizon at times when you could have seen the Moon, i.e., between sunset and moonset. However, if you claim that you couldn't see the Moon on a certain day, and several of your classmates get nice pictures, you have a problem.
• The most crucial observation is the one for the day that starts the Muslim month, usually the second or the third day of the Chinese month. Use Khalid Shaukat's Moonsighting.com, MoonCalc or Accurate Times to predict when the crescent will first be visible. Make a serious effort to see it that night. Don't give up before the time of moonset. If you can't see it, I want at least a picture of the western part of the sky between sunset and moonset.
• This is a major exercise in team management! You can do it while on trips, dates or whatever! On the crucial first day of the Muslim month, you may want to divide your group into several teams in case one part of the island is cloudy or one one team has picked a bad spot. For the other observations, you may schedule different people in your group to attempt to make observations on different days.
• It is very hard to take good pictures of the Moon. Please don't despair; it's just as hard for everybody else! You may want to buy or borrow a tripod. Please don't try to impress me with photos from the web or past homework! If you are a serious photographer and get very good pictures, please include some technical details to convince me that you actually took them yourself.

How to Estimate Angles in the Sky

• Measuring Angles in the Sky.
• Astronomy Note on estimating angles.
• Austin Astronomical Society -- How to Estimate Angles in the Sky.

Links

• The National Environment Agency on Singapore has a number of interesting pages, like Moonrise and Moonset Times and Moonphase Information for Singapore and Sunrise & Sunset Times for Singapore.
• The Astronomical Applications Department of the U.S. Naval Observatory has a lot of interesting pages on their Data Services and FAQ, like Virtual Reality Moon Phase Pictures, Phases of the Moon, Phases of the Moon and Percent of the Moon Illuminated, Rise, Set, and Twilight Definitions, Earth's Seasons Equinoxes, Solstices, Perihelion, and Aphelion 1992-2020, Sun or Moon Altitude/Azimuth Table for One Day and Sun or Moon Rise/Set Table for One Year. You can use the last one to print out a table of rising and setting times for the Sun and the Moon in Singapore. The coordinates of Singapore are 104 east and 1 north. Our time zone is UTC + 8.
• Moon info at John N's web site for Astronomy and Meteorology.
• If you need to do computations, there is a handy table of the equation of time and the Sun's declination on the Daily Sun Data at Tony Helyar's Home Page.
• Sun, Moon & Earth Applet and Sun Declination & Equation of Time from Juergen Giesen's GeoAstro Java Applet Collection.
• Khalid Shaukat's Moonsighting.com.
• Dr. Monzur Ahmed is the author of MoonCalc, which for many years was the leading lunar visibility and Islamic calendar software. He has pages on Astronomy and Islam and Ramadhan (Ramadan) and Eid-al-Fitr.
• The web page of the Islamic Crescents' Observation Project (ICOP) has a number of interesting articles. They also host the software Accurate Times by Mohammad Odeh. It is a Windows program for the Islamic calendar, Qiblah direction, and prayer times. There are samples of the lunar visibility charts on Visibility of Ramadan Crescent.
• Islamic calendar for Singapore by Majlis Ugama Islam Singapura (MUIS), the Islamic Religious Council of Singapore. MUIS seems to move the location of their calendar around from year to year. If the link doesn't work, go to their homepage and look under "Downloads" or do a search for Takwim (or Taqwim). This will give you MUIS's prediction for first visibility of the lunar crescent. But it is based on a dubious method, so you will often not be able to see the Moon on the day when MUIS claims that you will. Please see my page on The Islamic Calendar.
• Islamsk Råd Norge, Hilalkomiteen (in Norwegian) explains the policies of the Islamic Council of Norway.
• HM Nautical Almanac Observatory in the UK makes very nice lunar visibility charts. Their Websurf contains a wealth of information, including Global First Sighting of New Crescent Moon information for the last couple of years. The charts for the current month are also available at Moon Watch.
• Moon Watch.
• Crescent Moon Visibility and the Islamic Calendar from the Astronomical Applications Department of the U.S. Naval Observatory.
• Moon Research Centre (U.K). The article on Policies Adopted in Britain by Muslims in Celebrating Islamic Festivals is essential reading! They also have a copy of the RGO Astronomical Information Sheet No. 6.
• Predicting the First Visibility of the Lunar Crescent, The Umm al-Qura Calendar of Saudi Arabia, Islamic-Western Calendar Converter (Based on the Arithmetical or Tabular Calendar) and Internet sites over de islamitische tijdrekening (in Dutch) by Robert H. van Gent.
• Crescent-Sighting and Islamic Calendars and Islamic Astronomy: Questions, Comments and Correspondence by David McNaughton.
• Moon Phases.

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