Tuesday, October 23, 2007

A kind of Calendar

Sometimes it is argued that living in a city alienates people from nature, and that, for example, the conscious experience of the course of seasons gets lost. There may be snow on the streets on a few mornings, or the colour of the leaves on the trees changes from green to red, but otherwise, it's just the length of daylight and the average temperature that distiguishes summer from winter.

However, if you keep your eyes open, city landscapes with skyscrapers and big buildings offer quite unexpected, archaic means to follow the course of the seasons, and allow even to establish some primitive forms of calendars.

For example, a few years ago, I was quite fascinated to discover that in the weeks around the summer solstice, the late evening Sun casts the distinctive shadow of a tall hotel building in my neighbourhood onto one of the bank towers in downtown Frankfurt, just before setting behind the Taunus crest. Another bank building erected a few years ago, which now blocks the afternoon Sun from our apartment, serves as a giant screen for the shadow of the same hotel tower just at sunrise around the equinox.

And about four weeks after the fall equinox and before the vernal equinox, I can witness kind of a solar eclipse in the late morning from the kitchen window: For a few minutes, the Sun disappears behind the pyramidal tip of the Messeturm:

At 9:58 in the morning,

the Sun disappears behind

the tip of the Messeturm.

Eight minutes later, at 10:06,

it reappears again, the eclipse is over.

On Sunday, October 14, the Sun's arc was still so high that its disk just touched the very tip of the tower. I couldn't make any observations over the week, and this Saturday, when the photos were taken, the path of the Sun crossed already behind the base of the pyramid. I usually try to observe this "event" each fall and spring, and now I know, we are around October 20.

Maybe you have similar solar calendars in your city?


  1. Hi Stefan,

    Living in suburbia and being a gardener makes it doubly unlikely that I'd make any such observations as you did. Dandelions sprouting or leaves falling on my lawn are markers of the seasons.

    Your exposures almost directly into the sun, but still not totally obliterating the foreground are, IMO, very good.


  2. They just announced in the radio that tomorrow the night temperature will have it's first drop below zero. I'd appreciate some lack of Calendar every now and then. But thanks for the photos, these are really great! You know, last week in NYC I more or less accidentally took a subway through Brooklyn, to the point where its no longer underground, and there is this endless series of Graffiti painted backyards etc. There weren't all that many people in the train, and I was pretty tired. When I looked out of the partly blind window through the scratches, somewhere in the distances there was the Manhattan skyline, not very clearly visible. And it looked SO like Frankfurt - going out to the West, Gallus, Westbahnhof, Rödelheim, dirty suburban backyards, Graffiti painted walls, the skyline in the background. Well. In a certain sense all larger cities are similar, and the announcements in the trains equally ununderstandable. näschstahald galluszurückbleimbitte dietürnschließn

  3. It would be hard even as a naturalist not to see the how the sun changes it's position from the summer months to the winter? :)

    Hot to cool? Of course depending where you are on the globe.

    Should look at the layout of the Giza Plateau sometime and the pyramids. Solar clock?

  4. Web cams and blogs with photos made our world a smaller place. Your post made me wonder if there is a way to customize Google Earth, so that one can have a version of Google Earth, marked with photos of sun calendars, and as a function of time, spread over the globe? I think it would be cool to fly over the Earth from sun calendar site to sun calendar site, at different times of the year.

  5. Hi Stefan,

    One begins to wonder what use ancient Egyptians had for those pyramids and obelisks?

  6. Dear arun,

    Dandelions sprouting or leaves falling on my lawn are markers of the seasons.

    ... that's definitely an even more "natural" calendar ;-)

    On the other hand, what is so fascinating to me with these "city" calendars, that these shadows cast from one large stone building onto another one at very specific times of the year are so archaic. It's the same method as used 5000 years or so ago...

    Your exposures almost directly into the sun, but still not totally obliterating the foreground are, IMO, very good.

    That has also surprised me - after all, I have just used my three-year old, quite simple digital camera, with no special precaution. I didn't even use a tripod or so to make sure that the perspective is always the same. So I'm quite happy with the result ;-)

    Dear Bee,

    And it looked SO like Frankfurt

    wow, you compare Frankfurt to NYC ;-)... but yes, indeed, from that S-Bahn going out to the West, Gallus, Westbahnhof, Rödelheim Frankfurt looks really impressively big and metropolitan :-)

    Dear Amara,

    that's a cool idea - somehow attaching a photoblog to google maps, with special calendar views. Combining the "time dimension" of a blog to the "space" dimension of a map...

    Best, Stefan

  7. Hi Plate, doug,

    I am quite convinced that at least some aspects of ancient Egyptian pyramids and obelisks had calendar functions...

    For sure the Romans used obelisks as gnomons for sundials. For example, there was the big obelisk of Augustus, where parts of the sundial marks in the floor have been excavated.

    BTW, searching for the Augustus obelisk I just came across the Long Island City Sundial project, where a buliding similar to the Messeturm is "used" as a gnomon of a gigantic sundial. If ever I don't know what to do with my time, I should calculate similar shadow patterns to be used as sundial marks for the Messeturm...

    Best, Stefan

  8. As archiac as this "method of measure" may seem, it has captured our fascination in more ways then one.

    Plato's cave?

    You tend to get this consistancy of "historical thought" once one sees the connection?:)Euclid

    How could one not percieve geometry at work after seeing what the sun can do in regards to these calendars?

    One could of course propose the Egyptian new year, where the dead are placed, in relation to the pyramid, and the design of that history according to the clock, but then ,it may be in contradiction to what is current.

    Even more ancient, the Medicine Wheels.

  9. Dear Stefan:

    wow, you compare Frankfurt to NYC

    Well, but it's like comparing big apples to small peanuts ;-)

    Frankfurt looks really impressively big and metropolitan

    Says the guy who grew up in a village with < 1000 inhabitants ;-p That was actually not *quite* what I said. What I actually said was that the depressive interior of the subway, the Graffiti painted walls, the dirty backyards, and the view from the train from which I could *not* clearly see the skyline reminded me of Frankfurt... Best,


  10. Hi Amara,
    that sounds like a cool idea.

    Stefan has started with pics of Frankfurt and invites visitors to do the same in their Cities.

    People see all sorts of things when they look at the SUN and Solar Calendars

  11. Wow, you just rediscovered the ancient technology behind Stonehenge

  12. Hi Anonymous: See also Stefan's earlier post A modern Stonehenge. Best,


  13. I see Bee beat me too it.

    Q9:"People see all sorts of things when they look at the SUN and Solar Calendars"

    Time and how one views the cosmos for sure.

    Capturing the understanding of Hooft, Heisenberg and others, you see Stefan working the principals "outside of himself" with his environment. Inside the universe.

    Like, how one can "view the cosmos" or how "dimensionality is reduced to the now."

    The evidence of "the beginning" is not gone?

    The shadows reveal this, and so it reveals the mathematics of this universe.

    Or, how the matter of the diamond has it's structure implanted in the mapping of it's features?

    Yet, "the mapping" is closer to the beginning, then, the matter is of itself. :)

  14. Hi Plato, just been around your place, but comments seems to be off on your latest post.
    Casdok asks: How do you see the world

    Apologies to Stefan, for going too far off topic

  15. Quite simple really Q9.

    No Sun, no Stefan's post. :)

  16. Manhattanhenge:


    Makes me laugh every time I read/hear it.

    I don't know if there are other such occurrences in NYC but now I'm eager to find them.

  17. Hi Diana:

    Thanks for the link! Bad planning though, they could have turned the lattice by one degree and made it July 4th instead of 13th or so ;-) Best,


  18. Hi Bee:

    "Lattice" - you mean the grid?

    Having missed the sunset Manhattanhenge I look forward to the sunrise one, in early December. I'll post pictures - if I can get up that early. (No promises!)

  19. Hi Diana,

    great link, thank you very much! The flickr photos tagged Manhattenhenge are really impressive - looking forward to see your December Manhattenhenge sunrise :-)

    Sometimes some people call Frankfurt Mainhatten (because it's on the river Main...), but there are no real street canyons... However, a few days before and after the summer solstice, sunset is exactly in the direction of one of the main streets running from the central station along the Fair towards to northwestern outskirts - that's kind of a mini-Mainhattenhenge ;-).

    BTW, to check if, and when, sunset or sunrise occurs along the axis of a street, try to measure the orientation of the street using its azimuth - that's the angle measured against North in eastward direction - and compare with the azimuth for sunrise or sunset, which can be computed online at different websites. At this site of the US Naval Observatory, you can calculate tables of the Sun's azimuth and altitude for any place on Earth given its longitude and latitude, which is quite useful if you want to know the direction of the the Sun a few minutes before sunset or after sunrise. So, Be a Calculating Photographer ;-)

    Best, Stefan

  20. Stefan: I'm curious about Rome and maybe at the very end of my stay here, I'll have time to see if a 'Romehenge' exists.

    Already there is one interesting feature of the layout of the city, which is that an obelisk is placed at key points of the city (in front of or in back of the major churches), in order to guide pilgrims entering the city to the churches. And if you stand at the intersections of the major streets in Rome, then you can see some obelisks at each end. So I'm thinking that these obelisks might make natural sun clocks in a stonehenge way.

    Already in Rome there is an obelisk as a sun clock: the Piazza Monte Citorio obelisk that has a gnomon on top to mark times of the year. See this page for a neat project to use cityscape 'needles' to mark time, similar to your idea.

  21. Bad planning though, they could have turned the lattice by one degree and made it July 4th instead of 13th or so.

    I can never remember which way precession is moving us, but I think in 1437, it would have been July 4th.

  22. Hi Syefan,

    Star time in a helix?

    Check out this summary report at:
    USA Today, ‘New spin on how stars are born’
    By Ker Than, SPACE.com
    Copyright 2007, SPACE.com Inc. ALL RIGHTS RESERVED.

    Original Letter:
    Nature 450, 71-73 (1 November 2007) | doi:10.1038/nature06220; Received 8 June 2007;
    Accepted 4 September 2007

    Antonio Chrysostomou, Philip W Lucas and James H Hough,
    ‘Circular polarimetry reveals helical magnetic fields in the young stellar object HH 135–136’.

    [Same HH (object) as previously discussed?]

    If this Nature Letter is confirmed, then the helix may also be able to tell time, both in DNA/RNA and in the stars?

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