Sandburg Center for Sky
Awareness
A Fairfax County Public Schools Planetarium
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Sandburg "Sun-Earth-Moon Day 2002"
Sundialing with Bill Devlin
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"Local" sundial enthusiast Bill Devlin visits with a group of Sandburg
students. Note the brass horizontal sundial (foreground, near the side
edge of table), the type of sundial more familiar to most people (often
seen in gardens).
Also note that as a resident of Front Royal, VA, Mr. Devlin is a member of
the Shenandoah Astronomical Society, not NOVAC (see
sign, background).
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The globe has been remounted to tilt not at its angle to the ecliptic
(23.5°), but at 39°, so that the axis of the globe is parallel to
the Earth's axis, like the gnomon of a sundial. Therefore, if the globe is
oriented along a N-S line, and is rotated so that Virginia is on top, the
Sun shines on the globe exactly as it does on the actual Earth! Spin the
globe and notice 24 hours of daylight at the North Pole; 24 hours of
darkness at the South Pole.
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Shown upper right (larger picture), left-to-right:
- A simple sundial model with a magnetic compass and bubble level inset,
used to make the point that the sundial must be properly oriented (aligned
N-S) and level.
- A homemade clinometer (or inclinometer). A protractor was traced on
paper, a weight (nut) hung from a string, sighting slot cut into top edge,
and pocket for nut (so string doesn't tangle during transport). Bill uses
the clinometer to get the correct angle on his "North Star Finder," which
is just an adjustable tripod made of two short sticks and a longer pointer
stick (see foreground of smaller photo, upper left).
- Next sundial has only a "T" on its surface to demonstrate that 6 a.m.,
6 p.m., and noon should form a perfect "T" on a manufactured sundial;
before buying a sundial, use the "T" test to see if the sundial is more
than ornamentel and might tell good time.
- Behind that one is an equatorial sundial (similar to the cardboard template assembled by Stratford
Landing ES students) that tells time only in spring and summer because
the Sun is too low to cast a shadow in fall and winter.
- Equatorial sundial with chop-stick gnomon. Bill made this sundial in
New York State for 42°N latitude; note shim to adjust sundial to the
latitude of Washington, D.C. (39°N).
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Photographs courtesy Judy Kramer, Sandburg MS Enrichment
Specialist,
and Petra Pair, Sandburg School-Based Technology Specialist.
Thumbnail images prepared using photoweb v1.2 by Phil Wherry.
S-E-M Day 2002 | S-E-M
Day 2001 | Sun "Block Party"
2000 | SCSA
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