ED-7WG: I've been thinking about developing one or more activities for use with the FCPS/NOVAC EarthDial. For the past few days, I've been recording ideas on a virtual sketch pad. Please take a look-see at what I've got so far and let me know what you think. Additional ideas for suggested activities/activity questions also invited. Note: this message is for internal use only, in other words, please DO NOT share this info. with "ED Central" (yet)! 1/2SkyGuy == [Questions excerpted from "Equatorial Sundial Activity Questions"... http://www.wsanford.com/~wsanford/exo/sundials/esaq.html http://www.wsanford.com/~wsanford/exo/sundials/esaq_tak.html <-- please do not share this resource with students!] Multiple Choice (circle correct answer within brackets): ------------------------------------------------------- The 12 o'clock hour line (also known as the meridian line) that divides the dial face in half represents your [line of latitude, line of longitude]. As viewed from above the North Pole, the Earth appears to rotate [clockwise, counterclockwise]. As viewed from above the South Pole, the Earth appears to rotate [clockwise, counterclockwise]. (If necessary, experiment with a globe before answering this question.) Sun shadows fall in the [same, opposite] direction as the Sun. During the day, the gnomon shadow appears to move [clockwise, counterclockwise] around the [upper, lower] dial face. The Earth's [rotation, revolution] causes the gnomon shadow to appear to move around the dial face. The Earth's [rotation, revolution] causes the gnomon shadow to move from the upper dial face to the lower dial face, and vice versa. When Daylight Saving Time is in effect, Solar Time (sundial time) is [earlier, later] than Standard Time (wristwatch time). Hint: Remember the mnemonic, "Spring forward; fall back." Short Answer (be clear and concise): ----------------------------------- When doesn't a [horizontal] sundial (such as ED-7) work? Why do time zones generally run north-south instead of east-west? [Why are time zones 15 degrees of longitude in width?] The Sun and Earth are parts of an interconnected system. Use the words "rotation" and "revolution" to summarize your short-term (day-long) and long-term (year-long) observations of the EarthDial. For Further Thought: ------------------- Are you clock-wise? Why is "clockwise" clockwise? Why is it incorrect to say that 12 noon is 12 p.m.? Would your EarthDial read the same time as another sundial 100 miles directly north of you? Would the shadows be the same length? Does an EarthDial work the same north and south of the Equator? Would an EarthDial work at the North and South Poles? == [Misc. new ideas...] Why is "clockwise" clockwise? Remember, mechanical clocks were invented in the Northern Hemisphere. [Refer to time-lapse animations.] For horizontal sundials located in the Northern Hemisphere, why are morning times located on the western side (left side, facing north) of the dial face? Question re: Sun az/alt On a daily basis, when are shadows longest? Shortest? On an annual basis, when are shadows longest? Shortest? [See solstice/equinox diagram: http://www.wsanford.com/~wsanford/exo/sundials/annual_sun_path#diagram Also, annual n-s migration of subsolar point.] Why is 12 noon LAT not necessarily coincident with 12 noon Standard Time? (Refer to 07FEBO4image1220.jpg; Standard Time Correction = +22:10.) [Relate to analemma: http://www.georgefcram.com/education/gr1.jpg] > Tracing the Analemma SCSA Calculate and Chart the Analemma - A year-long projection of the Sun's image on a horizontal surface. (See also Related Resources.) [At the same time every day (say, once every two weeks), place Avery dots on the EarthDial face (or hardcopy facsimile). At the end of one year, dots should trace the analemma!] > From the Smithsonian Institution, Eyes on the Sky, Feet on the Ground - Hands-On Astronomy Activities for Kids. See Chapter Two - The Earth's Orbit, Activity 2-4: The Analemma (constructing a ceiling analemma). > Two interrelated activities from Paper Plate Education: Sub-Solar Cup; and Analemma Project. > NSTA http://www.nsta.org/index.html >From the National Science Teachers Association, Astronomy with a Stick - Daytime Astronomy for Elementary and Middle School Students http://www.nsta.org/awsday -- It's 11 a.m. The FCPS/NOVAC EarthDial is visible in the current webcam image, but the gnomon does not cast a shadow. What information is available on the ED-7 home page that could help you to explain your observations. [Correlate EarthDial image with TWC "Weather Magnet."] Geography/Location. Use world map to plot lat/lon of all EarthDials; compare with map of Time Zones. Use/credit "Cram" world map; hyperlink from grayscale world map (used on ED-7 home page) http://www.georgefcram.com/education/l6wm.html#l1 http://www.georgefcram.com/education/wm4a.jpg http://www.georgefcram.com/education/45wm_4.pdf Note: New Orleans is located exactly on the STM for the CTZ! "Latitude and Longitude Working Together The global grid system uses both the parallels of latitude and the meridian of longitude. When giving a location in latitude and longitude, latitude is always first. As an example, the location for New Orleans is 30 N, 90 W. This is read as 30 degrees north latitude, and 90 degrees west longitude. [insert map graphic] The map above shows the New Orleans location. New Orleans is located where the parallel of latitude that is 30 degrees north of the Equator crosses the meridian of longitude that is 90 degrees west of the Prime Meridian." http://liftoff.msfc.nasa.gov/academy/ROCKET_SCI/CLOCKS/TimeZones.GIF When is dark not necessarily dark? [Image processing activity using either NIH Image or Scion Image. Use one or more of Tom Hennig's enhanced "MoonDial" images.] ================================================================= Walter Sanford, Director Carl Sandburg Middle School Center for Sky Awareness 8428 Fort Hunt Road Sandburg Planetarium Alexandria, VA 22308 Fairfax County Public Schools Work: 703-799-6169 -6197 (fax) E-mail: wsanford@wsanford.com Home: 703-765-9392 AMS Project ATMOSPHERE Atmospheric Education Resource Agent SCSA, Geosystems, & Camp T-Equity - URL: http://www.wsanford.com/ =================================================================