What's New Under The Sun
Getty Research Institute on the Solstice
Saturday, 22 June 2024 19:38
Off Interstate 405 in the hills of Los Angeles is the Getty Research Institute, part of the campus of The Getty Center. The Center houses the free Getty Museum, the Getty Library, Getty Research Institute, Getty Foundation, and Getty Conservation Institute. The Getty Research Institute opened its doors to the public in December of 1997, where besides the thousands of books, art collections,...
Preparing for the Solar Eclipse of April 8th 2024
Sunday, 24 March 2024 18:30
There are lots of maps showing where to go for the April 8th 2024 total solar eclipse and others showing the statistical chance of clouds such as https://www.washingtonpost.com/weather/2024/02/22/april-eclipse-clouds/ From Little Rock Arkansas to the Mazatlan coast there is a high probability of clear weather. The cities from Indianapolis through Cleveland OH, Rochester and Syracuse...
Seiko Designs Equatorial Sundial Watch
Sunday, 24 March 2024 01:42
When is a watch not a watch? When it unfolds into an equatorial sundial. The watch, designed by Yu Ishihara is called a "Watch Exclusively for Sunny Men" and was part of a contest sponsored by Seiko to "help reimagine what a watch can be", aimed at creativity and perhaps for eventual production. Read about it at...
Rare Astrolabe Discovered by Chance in Verona Museum
Wednesday, 06 March 2024 00:17
Dr. Federica Gigante, from Cambridge Univerity's History Faculty, discovered a rare astrolabe sequestered in a museum at Verona, Italy. Publishing in Nuncius (1 March 2024) Dr. Gigante presents "a hitherto unknown remarkable astrolabe from Al-Andalus which likely belonged to the collection of Ludovico Moscardo (1611–1681) assembled in Verona in the seventeenth century. The...
World Sundial Day
Friday, 23 February 2024 16:53
Spanish sundialist Esteban Martínez has launched the resolution to establish the World Sundial Day to occur each year on the Spring Equinox. According to the petition circulated by Martinez,
"Reason Sundials represent the union of disciplines as disparate as Astronomy, Mathematics, [and] Geography...They have an undoubted didactic value in teaching astronomy to young people and as...
Smithsonian Photo Contest - Jaipur Sundial
Sunday, 05 November 2023 16:30
Smithsonian Magazine holds a photo-of-the-day contest. Winner on 30 Oct 2023 was Harita Sistu who took a photo of the large sundial of Jantar Mantar, Jaipur India (taken in July 2022). Harita notes: "I wanted to try my best to capture just how massive the instrument is and bring focus into the incredible skill that went into designing and constructing it."
See other NASS...
Houston Pavilion - World's Largest Sundial
Friday, 14 July 2023 23:08
A sundial or performance center or solar generator? It's all three. Called the Arco del Tiempo (Arch of Time), the design by Berlin architect Riccardo Mariano provides the projection of the sun's rays onto the ground through tinted glass apertures spanning the length of its arching ceiling. The elliptical shaped spots change every hour, telling "the solar time each day and delight visitors with...
Sun Tower Update
Saturday, 01 July 2023 00:36
According to NewAtlas.com (https://newatlas.com/architecture/sun-tower-open/), construction of the Sun Tower exhibition building and outdoor theater is underway in the Chinese city of Yantai. The tower is being constructed by a French firm, Ducks Sceno and the engineering firm Arup, raising to 50m (164 ft) gracefully into the sky. The tower symbolizes the historic watch towers of...
Point of Infinity Hyperbolic Monument in San Francisco
Sunday, 25 June 2023 22:17
Julie Baumgardner in The Art Newspaper of Jan 13, 2023 reports on the construction project of Point of Infinity, a nearly 70 foot (21m) hyperbolic cone will reach toward the sky as part of a 50 million dollar park development on Treasure Island and Yerba Buena Island.
In a competition held by the San Francisco Arts Commision on behalf of the Treasure Island Development Authority, Hiroshi...
Ice Sculpture Ephemeral in Time
Thursday, 30 March 2023 00:03
In the Swiss mountains near the resort of Zermatt just beneath the Matternhorn, Stir World reports that "famed luxury Swiss watchmaker Hublot announced Daniel Arsham as its new ambassador, with a compelling piece of temporary land art. Aptly titled "Light & Time", the work is a Hublot-inspired 20-metre sundial resting in the shadows of the Matterhorn mountain."
This sculptural is billed as...
Preparing for the Solar Eclipse of April 8th 2024
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There are lots of maps showing where to go for the April 8th 2024 total solar eclipse and others showing the statistical chance of clouds such as https://www.washingtonpost.com/weather/2024/02/22/april-eclipse-clouds/ From Little Rock Arkansas to the Mazatlan coast there is a high probability of clear weather. The cities from Indianapolis through Cleveland OH, Rochester and Syracuse NY and Burlington VT have a good chance of cloud cover. Fortunately such websites as Time and Date https://www.timeanddate.com/live/eclipse-solar-2024-april-8 will live-stream the eclipse with totality beginning 12:38pm EDT and on YouTube Through the Eyes of NASA - Official Broadcast at https://www.youtube.com/watch?v=2MJY_ptQW1o
But what will you see during totality when you can take off your solar protective glasses? Predictive Sciences Inc, funded by NASA and the National Science Foundation (NSF) have created a " Data-Assimilative, Continuously Running Prediction Model Updated in Near Real Time" showing what the solar corona may look like during totality. The prediction is based on the current state of sunspots, solar flares, corona mass ejections, and the sun's magnetic field.See it at: https://www.predsci.com/corona/apr2024eclipse/home.php
The corona is expected to be much more active and extensive than the total eclipse that crossed the United States in August 2017 as the sun isnow approaching sunspot maximum
Today - Chicagohenge
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The date is Sep. 22, 2022, the date of the fall equinox. Although this is supposed to be the day of equal day and night, we know it's not exactly correct. We measure daytime from sunrise to sunset, measured as the first and last light from the sun peaking over the horizon. When we include sunrise and sunset plus atmospheric refration, at mid latitudes daylight wins by about 10 minutes (not even counting twilight).
![]() Chicagohenge photo by Tim Hara
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But something magical happens as the sun sets due west on the equinox in Chicago. The sunset direction matches the direction of the Chicago grid of East-West streets. The effect is known as Chicagohenge.
From the Adler Planetarium website (https://www.adlerplanetarium.org/blog/chicagohenge/): "Chicagohenge occurs twice a year and happens when the Sun directly lines up with Chicago’s east-west facing streets ... To fully understand Chicagohenge, you have to be aware of the two main factors that cause it: Chicago’s grid plan and equinoxes...The present-day Chicago grid system can be attributed to the Public Land Survey System -- a surveying method created in 1785 that was used to divide land for selling and settling. But this style of city design has been around since the dawn of civilization and can be found in the ruins of ancient Rome, Greece, and others [sometimes creating solar alignments in these cities such as Manhattan Henge] ... Fun fact: Chicago’s streets line up almost perfectly with the cardinal east and west directions on a compass. This in turn, sets up the perfect stage for Chicagohenge to take place."
The Planetarium Blog continues. "Since the Earth’s axis is tilted, sunlight is not always distributed equally. At any given point, one-half of the Earth is tilted towards the Sun more than the other. As the Earth orbits around the Sun, the part that was tilting away from the Sun begins to be the part that is facing towards the Sun. This is why we have seasons! ... There are two equinoxes each year, one that marks the start of spring (Spring Equinox) and one that marks the end of summer (Autumn Equinox). Thanks to Chicago’s perfectly lined grid system, the bi-annual equinoxes mark a time when the Sun rises and sets directly in line with Chicago’s east and west streets, causing Chicagohenge! ... Finding a place to spot Chicagohenge is a no-brainer! Simply find one of Chicago’s east-west facing streets, plop a seat, and enjoy the view."
Eclipse of Sun by Phobos Seen by Perseverance Rover
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On April 2, 2022 the Perseverance Martian rover's Mastcam-Z camera looked sunward and took a video of the eclipse of the sun by the "potato-shaped" moon Phobos.
According the NASA Mars Exploration Program site, "It’s the most zoomed-in, highest-frame-rate observation of a Phobos solar eclipse ever taken from the Martian surface." NASA reports that "Several Mars rovers have observed Phobos crossing in front of the Sun over the past 18 years. Spirit and Opportunity made the first observations in 2004; Curiosity in 2019 was the first to record video of the event. Each time these eclipses are observed, they allow scientists to measure subtle shifts in Phobos’ orbit over time. The moon’s tidal forces pull on the deep interior crust and mantle of the Red Planet; studying how much Phobos shifts over time reveals something about how resistant the crust and mantle are, and thus what kinds of materials they’re made of."
Watch the video: https://mars.nasa.gov/news/9172/nasas-perseverance-rover-captures-video-of-solar-eclipse-on-mars/
Art Project: "Unit of Measurement"
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The Land Institute is a not for profit organization based in Salina, Kansas, having a goal to create an agriculture system that mimics natural systems in order to produce ample food and reduce or eliminate the negative impacts of industrial agriculture. A mile north of the Institue is their Marty Bender Nature Area where Owen Brown has created an art project "Units of Measurement". According to Jason Beets of the Salina Journal, his project "consists of three sets of sun dials created from praire-colored angled flag poles to symbolically represent the passage of time."
The idea is to meditate on the passage of time. The first set of three poles, called "In the Beginning" is 1,190 feet east of another set of poles called "The Passage of a Second". According to the artiist, this is the distance that the earthrotates in one second. A third site, called "From the Future" is located 723 feet north of "In the Beginning" is placed such that at "... dawn of the summer solstice, the shadows of the sundials at “From the Future” will touch [point to] the sundials at “The Passage of a Second.” Owen said, "I want this installation to make us more aware of where we are, who we are, and how we are ... in relation to the earth, to what we grow, and to what nurtures us."
Interesting art but very poor science. For each cluster of three flag poles, only the one point to North can work as a sundial. And the pole needs to be at an angle from the ground equal to the latitude of 38.855° N. From the photo, the angle is closer to 60°. Fortunately there are no hour lines on the ground to show the incorrect time of the shadow.
Updated Content: 28 Feb 2022
We've recomputed "The Passage of a Second" using Earth Centered Earth Fixed (ECEF) coordinates for the latitude of 38.855° N and an altitude of 1,227 ft attributed to Salinas, KS. The result is an earth radius of 4.973775 x 10^6 meters giving a circumference of 31,251.15km. But to count exactly one revolution of the earth (in inertial space) we need to use the sidereal day of 86164.1 sec rather than the mean solar day of 86400 sec. And just as Owen Brown has separated "In the Beginning" and "The Passage of a Second", the distance is 1190 feet. The angle from east of "From the Future" 723 feet north of "In the Beginning" as seen from "The Passage of a Second" is 31.28° or 121.28° from south. The first rays of the sun appear on the eastern horizon when the center of the sun is actually 0.833° below the horizon. The sun's apparent position is due in part to atmospheric refraction. Taking this effect into account, sunrise on the summer solstice will occur at an azimuth from south of 121.3°, the alignment used by Owen Brown.
Indeed the sunlight is coming from the future on the solstice, travelling the Pathagorean distance of 1,392.4 feet in (424.4m) between Future and Passage requires 1.4 microsecond. Owen Brown's simple constructs with precision placement is something to be contimplated.
Read more at: http://www.salina.com/news/20181027/land-institute-art-project-reflects-on-time-nature
Cosmic Room on the Equinox - 2018
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The heart of the Cosmic Room is an unusual vertical meridian sundial created by sunlight passing through a slot on the roof above. In winter the solar meridian transit is labeled with a column of blue tiles and at the spring equinox the tiles change to orange. The sign "Analemma 12:45" indicates civil time on the spring equinox when the sun is on the local meridian. With the sun overhead, the beam of light follows the vertical set of tiles downward until it reaches the boundary between orange and blue tiles - the equinox has arrived. Ruben Nohitol has been photographing this event for the last 16 years, every year since 2002. From a ceiling hole Ruben marks the image of the sun at 12:45 on the floor with a small green circle. He does this on dates throughout the year(s), not only creating a nice analemma, but does it with such precision that he is able to notice the slight shifts in solar equinox position through the leap year cycle of four years.
More impressive is the due west sunset on the equinox. A beam of light streams though a hole in the western wall of his hacienda, across the living room, through a square hole between rooms, across the Cosmic Room grazing past the vertical sundial and its tiles, and lands as a bright solar disk at the far end of the Cosmic Room on a vertical wood screen mounted on an exit doorway. To add to the drama of the setting equinox sun, Ruben placed a model of the pyramid of El Cerrito on a shelf in the Cosmic Room blocking some of the sun's rays. The result is a shadow of the the pyramid against the solar disk, giving the illusion of thesun setting over the great pyramid. You can see his vertical meridian and more at http://www.makeaholeinthewall.com and the sundial in operation at http://www.sundials.org/index.php/dial-links/videos/meridiane See his patience to photograph the real setting sun over the pyramid of El Cerrito in Queretaro, Mexico at http://www.sundials.org/index.php/dial-links/videos/analemmas-time-and-motion
Cosmic Room with Solar Analemma
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[photo courtesy of Ruben Nohuitol]
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Ruben Nohuitol of Queretaro, Mexico has a unique solarium or “cosmic room” to observe the rays of the sun throughout the year. He has patiently constructed a wonderful time-lapse video following the sun every day at 12:45 pm. His construction has a vertical meridiana beam of light descending and then ascending the wall as time passes throughout the year. A second sky-light gnomon creates a classical analemma on the floor.
Moon Time Using an Analemmatic Sundial
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![]() By the Light of the Moon
Photo by Dr. Jeff Kretsch
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The analemmatic (human) sundial at Turner Farm Observatory Park in Great Falls, VA made by Eagle Scout candidate Kenny Dieffenderfer and Troop 1547 marked a unique place in sundialing history this July 23rd. The Analemma Society sponsors free Friday night public viewing of the heavens through telescopes at Turner Farm's Roll-Top Observatory. But just outside the Observatory on the sidewalk is Kenny's analemmatic dial. Could this dial tell correct time by the light of the moon?
On July 23rd this question was put to the test. It was almost exactly a full moon and the sky was clear. As can be seen in the accompanying photo taken by Dr. Jeff Kretsch at approximately 10:10pm EDT, the lunar shadow of a volunteer human gnomon cast a shadow of about 9:10pm standard moon civil time. How did this come about?
The important facts needed to make the analemmatic dial tell the correct "moon time" is knowing both the phase of the moon and the declination of the moon. On that night the moon was very close to being exactly a full moon and the declination of the moon was 25 degrees south of the equator. The maximum that the sun ever gets is 23.45 degrees south of the equator at the winter solstice. That means that (with practical precision) even though it was a late July night, the human gnomon must stand on the dial's zodiac walkway at the Dec-Jan winter solstice mark.
If this were the sun, we apply a plus 8 minute correction for the 77 deg west longitude of the observatory. The moon gets the same treatment. But what about the moon's phase and the "equation of time"? Here we find a fortunate coincidence: The moon was full moon at 10:37pm EDT on that Friday night, so by luck the moon was almost exactly opposite the sun. The moon's average full moon to full moon (a synodic month) is 29.53 days. Thus the average moon's lead or lag of a mythical full moon is about 49 minutes per day. Therefore the lunar phase correction is approximately 49 x 20/1440 = 0.68 minutes (41 seconds) ahead of the average full moon. Finally the sun's EOT for Friday July 23rd is approximately 6min 30 sec to be added to a dial's shadow to get civil time. But the moon opposite the sun has EOT in the opposite direction of minus 6min 30 sec. The net lunar correction is therefore +8.0 -.68 -6.5 = 50 sec, just less than one minute that needs to be added to that night's observation analemmatic shadow. One might say that the moon and sun were in perfect alignment!
Celebrate the Spring Equinox From Your Home-2020
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Here in Great Falls Virginia on the day of the Spring Equinox, March 19th, it's a rainy day. Perhaps that helps us want to stay inside with all of the travel and meetings restrictions imposed because of the Covid-19 virus. However, astronomical events aren't deferred because of human and biological issues. Late today the sun crosses the celestial equator and heralds in Spring. You can observe this event remotely thanks to Lowell Observatory in Arizona. Lowell Observatory will begin Live Streaming the event starting at 9pm EDT. "The spring equinox in 2020 occurs on Thursday, March 19 at 8:49pm MST/PDT (3:49am GMT), when the Earth's axis is exactly perpendicular to an imaginary line drawn between the Earth and Sun. On the equinox, the Sun rises due east, and it sets due west, no matter where you are on the Earth."
https://www.youtube.com/watch?v=LqP1Md85HHs&feature=youtu.be
2018 Sundial Calendar
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Dan-George Uza has prepared a calendar for 2018 "containing images of Romanian sundials and some daily astronomical information (the equation of time, the Sun's declination angle & zodiac sign, the Moon's phase & age etc.).... The calendar reflects the usual Romanian practice of starting weeks on Mondays, being the first working day, although orthodox religious calendars have reverted to starting weeks on Sundays due to religious reasons since 2011. The days of the week have been translated to their English counterparts for your convenience. Apart from the last two, which have different etymological background, they all closely follow the names of the ancient planets" Luni - Luna (Moon), Marti - Marţe (Mars), Miercuri - Mercury (Mercury), Joi - Joe/Jupiter (Jujpiter), Vineri - Venus (Venus) Sámbătă - from the Latin sa(m)bbatum meaning Sabbath, Duminica - from the Latin (dies) Dominica meaning day of the Lord. .... You may download the English version at the link below:"
https://goo.gl/FNafub
Dan explains that the calendar " includes a brief introduction to the Romanian calendar, such as an explanation for the names of the days and months, the dates of national holidays etc. This is actually my second calendar. I did the first one last year inspired by Fabio Savian's French Republican Calendar. A big thanks goes to Patrick Powers who was kind enough to correct my spelling mistakes for this English edition."
"The astronomical data was generated in Sun Ephemeris, Gian Casalegno's excellent software. The calendar is freeware so you may of course share it. It's intended for A3++ size paper (330x483mm) but I guess simple A3 will do."
"Have a Happy New Year or - as we like to say in Romanian - La Multi Ani!"
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