New York Marathon at mile 15 around 11am – Marilson Gomes dos Santos of Brazil, who later won, is at right in yellow. Runners just came from gnomon along Crescent Street, which will be the path of the shadow later in the day at 2pm.

? Half Sun on grid: Saturday, July 12 ? 8:25 P.M.

See below for more info.

From the Hayden Planetarium’s “Star Struck” email announcement by astronomer Neal deGrasse Tyson:

It’s that time of year again….MANHATTANHENGE 2008

What will future civilizations think of Manhattan Island when they dig it up and find a carefully laid out network of streets and avenues? Surely the grid would be presumed to have astronomical significance, just as we have found for the pre-historic circle of large vertical rocks known as Stonehenge, in the Salisbury Plain of England. For Stonehenge, the special day is the summer solstice, when the Sun rose in perfect alignment with several of the stones, signaling the change of season.

For Manhattan, a place where evening matters more than morning, that special day comes on Thursday, May 29h this year, one of only two occasions when the Sun sets in exact alignment with the Manhattan grid, fully illuminating every single cross-street for the last fifteen minutes of daylight. The other day is Saturday, July 12th.

These two days give you a photogenic view with half the Sun above and half the Sun below the horizon — on the grid. The day after May 29th (Friday, May 30th), and the day before July 12 (Friday, July 11) will also give you Manhattanhenge moments, but instead you will see the entire ball of the Sun on the horizon — on the grid. My personal preference is the half-Sun.

As you may know, had Manhattan’s grid been perfectly aligned with the geographic north-south line, then the days of Manhattanhenge would be the spring and autumn equinoxes, the only two days on the calendar when the Sun rises due-east and sets due-west. But Manhattan’s street grid is rotated 30 degrees east from geographic north, shifting the days of alignment elsewhere into the calendar.

Note that any city crossed by a rectangular grid can identify days where the setting Sun aligns with their streets. But a closer look at such cities around the world shows them to be less than ideal for this purpose. Beyond the grid you need a clear view to the horizon, as we have over New Jersey. And tall buildings that line the streets create a kind of brick and steel channel to frame the setting Sun, creating a striking photographic opportunity.

True, some municipalities have streets named after the Sun, like Sunrise Highway on Long Island and the Sunset Strip in Los Angeles. But these roads are not perfectly straight. And the few times a year when the Sun aligns with one of their stretches of road, all you get is stalled traffic solar glare temporarily blinds drivers.

So Manhattanhenge may just be a unique urban phenomenon in the world, if not the universe.

Note that a couple of years ago, an article in the New York Times identified this annual event as the “Manhattan Solstice”. But of course, the word “solstice” translates from the Latin solstitium, meaning “stopped sun,” in reference to the winter and summer solstices where the Sun’s daily arc across the sky reaches its extreme southerly and northerly limits. Manhattanhenge comes about because the Sun’s arc has *not* yet reached these limits, and is on route to them, as we catch a brief glimpse of the setting Sun along the canyons of our narrow streets.

IMPORTANT: For best effect, position yourself as far east in Manhattan as possible. But ensure that when you look west across the avenues you can still see New Jersey. Clear cross streets include 14th, 23rd, 34th. 42nd, 57th, and several streets adjacent to them. The Empire State building and the Chrysler building render 34th street and 42nd streets especially striking vistas.

Arrive a half-hour earlier than the times given below.

MAY

Half Sun on grid: Thursday, May 29 — 8:17 p.m. EDT
Full Sun on grid: Friday, May 30 — 8:16 p.m. EDT

JULY

Half Sun on grid: Saturday, July 12 — 8:25 p.m. EDT
Full Sun on grid: Friday, July 11 — 8:24 p.m. EDT
Downloadable Image of the July 2001 “Manhattan Sunset” as it first appeared in 2002 among the photo-essays of “City of Stars,” Natural History magazine:

http://research.amnh.org/users/tyson/ManhattanSunset.php

From the press release:

“New York, New York, New York is an interactive, multimedia installation. It is a continuation of Flux Factory’s interest in urban landscapes and takes inspiration from the Panorama, Robert Moses’ scale model of New York City in the Queens Museum of Art. Members of the Flux Factory art collective will work in collaboration with over 100 artists from all five boroughs and around the world to re-imagine the public and private spaces of New York.

Each artist will contribute a building, a landmark, a street, an avenue, a block, a park, a neighborhood, an expressway, a bridge, an island, an airport—one or several elements of the urban environment. All of these individual works will be combined to produce a cohesive yet chaotic installation, a multimedia, scale-model of the city. Instead of being an exact replica to scale of the city of New York, this project offers a mental map, a replica of an imaginary New York. The goal of the show is to explore the architectural and conceptual elements of everyday space. It is an investigation into the collective unconscious of the cultural capital of the planet: The sum of all of New York’s potential exposed in a great experiment in psychogeography.”

LIC Sundial model installed in Queens-panorama-area…and other installation views around NYNYNY:

After Tomorrow – in the lower Manhattan financial district by Momoyo Torimitsu

Cretaceous under Brooklyn (note to self to find artist name and piece title)

The Brooklyn Bridge with the Brooklyn Bridge

Leading men approach the LIC sundial gnomon.

Leading women, Paula Radcliffe and Gete Wami, emerge from the sundial shadow as the pass the gnomon.

The Long Island City Sundial is positioned such that this equinox line intersects the United Nations, across the river in Manhattan, at about 8:00am.

July 15 tour map

The LIC Sundial’s gnomon is positioned directly across from 53rd street (as pictured here in June 25th post), which could set up some interesting eclipse-esque action next week. Here’s a diagram:

More on Manhattanhenge:

Hayden Planetarium’s description, post on BLDG/BLOG, flckr photos tagged ‘manhattanhenge.’