{{Short description|Outdoor sculpture in Pima County, Arizona}} {{Orphan|date=February 2018}} {{Use mdy dates|date=March 2025}}
{{Infobox artwork | title = Sun Circle | painting_alignment = | other_title_1 = | other_language_2 = | other_language_1 =
| other_title_2 = | image = File:Sun_Circle_Sculpture_at_sunset,_August_8_2009.jpg | image_upright = | alt = | caption = | artist = Chris Tanz, Susan Holman, Paul T. Edwards | catalogue = | year = {{start date|1994}} <!-- If after 1583 CE, use {{start date|YYYY}} --> | completion_date = <!-- For a more specific date (post-1583): {{start date|YYYY|MM|DD|df=y}} --> | type = sculpture | material = split-face block, flagstone, concrete (smooth and exposed aggregate), sunlight | subject = archaeoastronomy | height_metric = <!-- (i.e. in metric units) --> | width_metric = | length_metric = | diameter_metric = | height_imperial = <!-- (i.e. in imperial units) --> | width_imperial = | length_imperial = | diameter_imperial = 50 | dimensions = | dimensions_ref = | metric_unit = m <!-- Note: this parameter must either use the value given or not be included --> | imperial_unit = ft <!-- Note: this parameter must either use the value given or not be included --> | condition = | city = Tucson, Arizona | museum = | accession = | coordinates ={{coord|32.301024|-111.0075825|type:landmark|display=inline,title}} <!-- Only use for the coordinates (when known) of the artwork itself, i.e. not for the site, building, structure, etc where it is kept, otherwise leave blank (or omit): {{coord|LAT|LON|type:landmark|display=inline,title}} --> | owner = Pima County Parks and Recreation | preceded_by = <!-- preceding work by the same artist --> | followed_by = <!-- next work by the same artist --> | website = http://www.christanz.com/sun-circle/<!-- Official webpage/site only: {{URL|example.com}} --> }}
The '''''Sun Circle''''' is a sculpture located within the Rillito River Park, a Pima County linear park running along the banks of the Rillito River north of Tucson, Arizona. Inspired by the archaeoastronomy of the southwestern United States Ancestral Puebloans in locations such as Chaco Canyon, ''Sun Circle'' uses astronomical alignments to cast shadows and light through apertures (windows) to align with corresponding windows on equinoxes and solstices at sunrise and sunset.<ref name="ASP"> {{cite conference | url = | title = Sun Circle: An Archeoastronomical Monument | first = Chris | last = Tanz | author = | author-link = | year = 2012 | conference = Engaging the Heavens: Inspiration of Astronomical Phenomena V | conference-url = | editor = Marvin Bolt, Stephen Case | volume = 468 | edition = | book-title = | publisher = Astronomical Society of the Pacific | location = Adler Planetarium, Chicago, Illinois, USA | pages = 77–82 | format = | id = | isbn = 978-1-58381-818-3 | bibcode = | oclc = | doi = | access-date = | quote = | language = | page = | at = | trans-title = }} </ref>
==Description== The sculpture is an outdoor circular concrete pad {{convert|50|feet|1}} in diameter circumscribed by eight walls {{convert|7|feet|1}} high by {{convert|12|feet|1}} wide. Four of the walls are in the cardinal directions, with four adjacent walls situated at angular distances of 23.4 degrees (corresponding with the axial tilt of the Earth) north and south of the east and west walls. The cardinal East and West walls have square windows, the four adjacent walls have isosceles trapezoid windows.<ref name=ASP/> thumb|right|Summer Solstice Sunset thumb|right|Autumnal Equinox Sunset thumb|right|Summer Solstice sunset seen through southeastern and northwestern walls At sunrise of any given day, the sunlight hitting the eastern walls will cast shadows across the circle, as light passes through the windows. As the Sun rises the shadows will shorten, appearing to shrink away from the western walls until the Sun reaches solar noon. The shadows of the three western walls then grow towards the eastern walls as the Sun continues west.<ref name=ASP/>
On the day of a summer solstice at daybreak sunlight passing through the window of the northeastern wall also passes through the window of the southwestern wall. As the Sun rises the light through the window travels down a path sandblasted into the southwestern wall and then travels along a line marked in the circular concrete pad. At late afternoon the sunlight through the window travels up a sandblasted path in the northeastern wall until at sunset the sunlight passes through both the northwestern and southeastern windows.<ref name=ASP/>
Winter solstice is similar except the sunlight first passes through the southeastern and northwestern windows at daybreak and passes through the southwestern and northeastern windows at sunset.<ref name=ASP/>
On the Equinox sunlight passing through all three eastern windows passes through the three corresponding western windows at daybreak and through the three western windows to the three corresponding windows at sunset.<ref name=ASP/>
==References== {{reflist}}
Category:1994 sculptures Category:Outdoor sculptures in Arizona Category:Concrete sculptures in the United States Category:1994 establishments in Arizona