Solar Alignments Cause 'Manhattanhenge' This Weekend

[LazyDays]

Andrea Thompson
Senior Writer
SPACE.com andrea Thompson
senior Writer


For 15 minutes around sunset on two days this summer, the sun will set in exact alignment with the cross streets of Manhattan's street grid, making the city's towering buildings function something like a modern-day Stonehenge.

They call it Manhattanhenge.

The first Manhattanhenge opportunity comes this weekend: On Saturday (May 30) at 8:17 p.m. EDT the ball of the sun will be half above the horizon, half below if you look west down a major cross-street (34th Street and 42nd Street are good viewing locations). On Sunday, May 31, the entire solar sphere will be visible just above the horizon at 8:17 p.m. EDT.

The second opportunity comes later in the summer, with another half-sphere sunset on Sunday, July 12, at 8:25 p.m. EDT and a whole-sphere viewing on Saturday, July 11, at 8:25 p.m. EDT.

These times are calculated every year by the astronomer Neil deGrasse Tyson, director of the Hayden Planetarium in New York, who coined the term "Manhattanhenge."

The "henge" comes of course from Stonehenge, the prehistoric monument in the Salisbury plains of England. The large structure of stones and earthen mounds is thought to be a burial ground that was oriented to face the midsummer sunrise and midwinter sunset.

Manhattan's street grid doesn't run geographically north to south, but instead aligns itself with the direction of the island. If the grid did run north-south, Manhattanhenge would fall on the spring and autumn equinoxes, the only two days during the year when the Sun rises due-east and sets due-west. (The equinoxes occur when the sun sits directly over the Earth's equator and the length of day and night are roughly equal.)

Because Manhattan's grid is rotated 28.9 degrees east from geographic north, the days of alignment with the cross streets are also shifted.

Manhattan's street grid was laid down by the Commissioners' Plan of 1811, which was adopted by the New York State Legislature.

New York isn't the only city that can have its own "henge" events: Any city crossed by a rectangular grid has days where the setting Sun aligns with the streets. But a clear view of the horizon and straight streets are needed, and New York might be the only city that fits the bill.

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There better be pictures somewhere. LOL

[mrpesca]

And we thought the ancients were brilliant astronomers. They just got lucky.
You can find a pattern in anything if you look hard enough.

[Dano]

Interesting.

[Jason]

Originally Posted by mrpesca

And we thought the ancients were brilliant astronomers. They just got lucky.
You can find a pattern in anything if you look hard enough.

I wouldn't bet on that. They made Stonehenge for a purpose... I mean, you don't just move 25-30 ton rocks around for decoration.

How about this 2000 year old "computer" found in the ocean a couple years ago? Was that coincidence too?


Gizmodo - Ancient Computer Found, Can't Play Doom - Ancient Computer
Ancient Greek Computer's Inner Workings Deciphered

[coldsteal2]

Originally Posted by Jason

I wouldn't bet on that. They made Stonehenge for a purpose... I mean, you don't just move 25-30 ton rocks around for decoration.

How about this 2000 year old "computer" found in the ocean a couple years ago? Was that coincidence too?


Gizmodo - Ancient Computer Found, Can't Play Doom - Ancient Computer
Ancient Greek Computer's Inner Workings Deciphered

That thing is amazing, there was a great special on it
on Discovery Chanel, how they rebuilt one from
the ruins of the original, by x-raying it puting it all into
a computer and figured out how to make it work

amazing machine for those days,

[Harpozep]

Originally Posted by coldsteal2

That thing is amazing, there was a great special on it
on Discovery Chanel, how they rebuilt one from
the ruins of the original, by x-raying it puting it all into
a computer and figured out how to make it work

I'd love to see that special. WOW. We were smart once. That's cool.

As to the Manhattan event I bet someone will film it from atop a skyscraper. Should be an interesting video.

[Jason]

Originally Posted by coldsteal2

That thing is amazing, there was a great special on it
on Discovery Chanel, how they rebuilt one from
the ruins of the original, by x-raying it puting it all into
a computer and figured out how to make it work

Yeah, that blew my mind. And then to find out about all the other advanced technology they had in ancient Greece... before it was all destroyed by the Romans. They had some very sophisticated surgical tools, for instance, and even did some brain surgeries.

[coldsteal2]

Yea destroyed by the Romans, and also the
library in Alexandria Egypt that had all the great
works of the ancients destroyed in a fire
no telling what great knowlege was in there.
Suposedly over 1 million scrolls

[mrpesca]

Originally Posted by Jason

I wouldn't bet on that. They made Stonehenge for a purpose... I mean, you don't just move 25-30 ton rocks around for decoration.

How about this 2000 year old "computer" found in the ocean a couple years ago? Was that coincidence too?

I didn't mean that all ancient technology was bogus. Just that they found a pattern in a street grid that wasn't planned out with any celestial meaning. I think we sometimes give ancient civilizations too much credit.

Someday someone will be sifting though our computer debris saying "wow, these people were very advanced for their time". I look around however and see dumbasses everywhere.

[LazyDays]

More pics here:

Manhattanhenge From Gantry Plaza State Park, Hunters Point, Long Island City, Queens, May 29, 2008

[StrangerNY]

Originally Posted by mrpesca

And we thought the ancients were brilliant astronomers. They just got lucky.
You can find a pattern in anything if you look hard enough.

Wasn't Stonehenge built so that the sun would shine through the 'gates' on the Vernal and Autumnal Equinoxes?

Something more than luck at work there, I'm thinking.

- D

[coldsteal2]

Tiny Stonehenge Spinal Tap

Tiny Stonehenge Spinal Tap

[StrangerNY]

Originally Posted by coldsteal2

Tiny Stonehenge Spinal Tap

I knew that'd be along sooner or later.

- D

[dennistruckdriver]

It's an 'enigma'....