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Projects: EarthDials

EarthDial Newsletter No. 9

26 April 2004

The project has added four new dials since the last Newsletter. After the frantic work of starting up, we are now entering into more of a steady phase. Meanwhile, on Mars, the Rovers of course are doing fantastically well and their missions have now been officially extended until next September, and perhaps even longer if all goes well. By now, there have been thousands of images that include the MarsDials. Check out the complete gallery of "Pancam" raw images available at http://marsrovers.jpl.nasa.gov/gallery/all/.

The new EarthDials are in Florida (on the roof of a small children's museum), in a backyard near the beautiful mountains of Utah, in central England (a dial of a more sophisticated design than the basic EarthDial), and on the roof of a building on our home campus of the University of Washington, where Hilda has her own ED now operating! Welcome to you all! I hope we can have at least four more new ones by the time of the next Newsletter.

There are now *16* active EarthDials (in 6 countries) and they are:

ED-1 Seattle, Washington, USA (122 W, 48 N) - Bill Nye's "standard"
ED-2 Columbia, Maryland, USA (76 W, 39 N)
ED-3 Ross, Ohio, USA 85 W, 39 N)
ED-4 Irvine, California, USA (117 W, 33 N)
ED-5 Tegucigalpa, Honduras ( 87 W, 14 N) - no-shadow days on 27 Apr and 14 Aug
ED-6 Costa Mesa, California, USA (117 W, 33 N)
ED-7 Fairfax County, Virginia, USA (77 W, 39 N)
ED-8 Valencia, Spain (0.4 deg W, 39 N)
ED-9 Atco, New Jersey, USA (75 W, 40 N)
ED-10 Bayan Lepas, Penang, Malaysia (100 E, 5 N) - no-shadow days on 3 Apr and 8 Sept
ED-11 South Pole (90 S, indeterminate longitude!) - Sun will not return until September equinox!
ED-12 Bellingham, Washington, USA (123 W, 49 N)
ED-13 Walcote, Leicestershire, England (1 W, 52 N)
ED-14 Panama City, Florida, USA (86 W, 30 N)
ED-15 Sandy, Utah, USA (112 W, 41 N)
ED-16 Newport, Shropshire, England (2 W, 53 N)
ED-17 Seattle, Washington, USA (122 W, 48 N)

As you know, we lost ED-11 at the South Pole because the sun set for six months (one month of which has already passed!), but we trust that Ethan will be able to "restart" his ED when the Sun returns in late September. We are cycling through all of the EDs for Featured Dial of the Week.

We have good prospects for new EDs in India (3 sites!), France, Spain, Croatia, Latvia, Canada, Venezuela, and Norway . In addition there are more US ones expected in Mississippi, Ohio, California, Maryland, and Massachusetts.   We need more non-USA EarthDials to fill in those empty latitudes and longitudes around the globe! Anything you can do to help this will be much appreciated.

- Check out the movie created for the shadow of ED-7's dial (Virginia, USA) on the March Equinox - the shadow of the gnomon is a straight west-to-east line. Others also have made great movies: we now have links to all the animations at http://www.planetary.org/mars/earthdial/Animations.html. These are marvellous for educational purposes. Please continue to make them over the entire range of the seasons, so that by the end of the year we'll be able to see how the daily tracks change over seasons, over time of day, and over latitude!

- On 3 April ED-11 in Malaysia celebrated "the day of no shadow" when the Sun passed exactly through his zenith (straight overhead) - this can only happen to sites in the tropics (latitude less than 23.4 deg). See his site for the photographic record of this event (to be exact, the sun was a mere 0.17 deg away from the zenith!). [Gregory of ED-11 has also sometimes placed his model MarsDial (which is available at ED-1's (Bill Nye's) website) on top of his EarthDial, where they make a handsome pair!] Next "tropical event" is Honduras, where the sun will pass through the zenith on Tue. 27 April - everyone should be observing the lack of a shadow at local solar noon!

- Next full moon is 2033 GMT on 4 May (in fact a total lunar eclipse will be visible then as the moon rises in Europe). If you can turn off all nearby lights, see if your Webcam can record the moon's shadow - you've then got a MoonDial! Very roughly, on full moon night, a shadow that reads, say, 2, means 2 am. You can also try this on nearby nights, but the moonlight will not be as bright and a reading of, say, 2, will mean *roughly* 50 minutes later each night.

- Some webcams get overwhelmed by too much light during the day since they're designed to work indoors. Bill Nye suggests a simple solution: put the lens from an old pair of sunglasses in front of your webcam lens and mid-day performance will greatly improve. For example, this might (surprisingly) make the images of ED-5 (Honduras) lighter, whereas other cameras that are overexposed near midday could be darkened. Try it!

- "Following in the footsteps of Eratosthenes" at http://www.inrp.fr/lamapphp/eratos/2004/subscribe.php?lang=en is a great project based in France and with many similar goals to ours. We are discussing possible ways to combine our efforts. Check it out!