The Earth & Sky Equatorial Sundial

Discovery Canyon School, Colorado Springs CO, USA

Latitude: 39 10' N. Longitude: 104 47' W.

Installed July 27, 2006

by John Carmichael (author) and Dave Bell (webmaster)

Photos, Drawing Plans and Model

DeltaCAD Drawing Plans: PDF Here or .dc Here or .dxf Here
Drawing of Face Markings and Their Functions: PDF Here
Model: Here
Dateline Installation: Here, Here
Dial Plate Installation: Here, Here
Gnomon Installation: Here
Nodus Installation: Here, Here, Here
Equation of Time: Here
Finished Sundial: Here, Here, Here, Here

Owner and Makers

Commissioned by: Academy School District 20
Designed by John Carmichael
Head Contractor: Chris Coulter
Granite & Gnomon by Eric Hendee at Erickson Monuments
Bronze Nodus by NASS member Chuck Nafziger

Description

The equatorial sundial faces and the dateline with The Equation of Time graph are sandblasted onto two 4 inch thick slabs of polished dark rose granite that each weigh about 1500 lb. The 3" thick, 61 1/2" long gnomon is a hollow 1/8" thick stainless steel tube that is reinforced inside with rebar and cement. It has a 6" bronze hand-sculpted world globe nodus bolted to the end. The granite slabs are embedded in 4 inches of concrete. The hour lines are corrected for longitude shift, not that it matters much, since the time shift in Colorado Springs is only about 52 seconds. The dial is just 0.217 east of the Mountain Standard Time Meridian which is located at 105 W. longitude. It is located on the Earth & Sky Plaza at the Discovery Canyon Campus of Academy School District 20. It's a K-12 school which specializes in science, math and avionics.

User Instructions

To Obtain Solar Time

The sundial stone has two triangular shaped faces with hour lines and numerals on each side of the stone. The north upper face tells Daylight Saving Time and only functions after the Spring (March) Equinox until the Fall (September) Equinox. The south lower face tells Standard Time and only functions after the Fall (september) Equinox until the Spring (March) Equinox. Around the Equinoxes, the sundial does not function because the sun shines onto the edge of the stone, parallel to the faces, making the gnomon's shadow invisible. To tell Solar Time, on the sundial face, look at the edge of the gnomon's shadow that is parallel to the hour lines. This is the side of the shadow that tells the Solar Time. Note that Solar Time is not always the same as watch time and will sometimes be ahead or behind watch time. To convert Solar Time to Watch Time, read the section below.

To Obtain Watch Time

Using The Equation of Time graph, add or subtract the number of minutes shown on the graph for today's date, to or from the time shown on the sundial.

To Tell the Time of Solar Noon

At Solar Noon, the sun is due south and is at its highest altitude above the horizon for the day. The rod gnomon's shadow is vertical on the face and the world globe's shadow is centered on the date line. At this moment, the time shown on the sundial face is Solar Noon. Solar noon on the South Face is at 11:59:08 am at 12:59:08 pm on the North Face.

To Tell the Date

At Solar Noon, estimate where the center of the globe's shadow is located along the date line. Read the date on the date line at this location.

To See How the Earth looks from Space

The shadow on the world globe simulates how the Earth is illuminated by the sun at that moment. It shows which half of the earth is in daytime and which half is in nighttime. The edge of the shadow shows which parts of the Earth are experiencing a sunrise or a sunset. The gnomon rod has a bolt hole and the globe is hollow. The globe is bolted to the end of the north end of the gnomon at Antarctica on the globe. The globe's polar axis is an extension of the sundial's polar gnomon. Colorado Springs is at the top of the globe.

To Find Out Sunset and Sunrise Times

On each face, the two one inch long lines, located next to the hour numerals, indicate the times of sunrise and sunset on the solstices. Horizontal hourlines are the times of sunrise and sunset on the equinoxes. To see the times of solar noon and the equinoxes see this drawing: Here

To Determine the Direction of True North and Magnetic North

The dark grey pavement on the ground to the North and South of the sundial shows the directions of True North and Magnetic North. See drawing on photo. Here

Related Websites:

Equatorial Sundials (with a photo collection of many equatorials): Here
Chuck Nafziger's equatorial in Seattle WA: Here

Contact:

John L. Carmichael
Sundial Sculptures
925 E. Foothills Dr.
Tucson AZ 85718-4716
USA
Tel: 520-6961709
Email: John Carmichael (author)
Email : Dave Bell (webmaster)

My Websites:

(business) Sundial Sculptures: http://www.sundialsculptures.com
(educational) Chinook Trail Sundial: http://advanceassociates.com/Sundials/COSprings/
(educational) Earth & Sky Equatorial Sundial: http://advanceassociates.com/Sundials/Earth-Sky_Dial/
(educational) My Painted Wall Sundial: http://www.advanceassociates.com/WallDial
(educational) Painted Wall Sundials: http://advanceassociates.com/WallDial/PWS_Home.html
(educational) Stained Glass Sundials: http://www.stainedglasssundials.com
(educational) Sundial Cupolas, Towers & Chimneys: http://StainedGlassSundials.com/CupolaSundial/index.html


Created on ... August 22, 2006

Updated on ... October 12, 2006