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 Manhattan has across the Hudson River to New Jersey. And tall buildings that line the streets create a vertical channel to frame the setting Sun, creating a striking photographic opportunity.

True, some municipalities have streets named for 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 several years ago, an article in the 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.

While we are on the subject, when viewed from all latitudes north of the Tropic of Cancer (23.5 degrees north latitude), the Sun always rises at an angle up and to the right, and sets and an angle down and to the right. That's how you can spot a faked sunrise in a movie: it moves up and to the left. Filmmakers are not typically awake in the morning hours to film an actual sunrise, so they film a sunset instead, and then time-reverse it, thinking nobody will notice.