(CNN) — New Yorkers are famously jaded -- they'll walk past a man in a bunny suit, juggling chainsaws -- but don't be surprised if you see throngs of them on street corners this weekend, aiming smartphone cameras toward New Jersey.
That's because Friday and Saturday are two of four days each year when the setting sun aligns precisely with Manhattan's east-west streets, framing the glowing orb between the city's steel and brick canyons.
Astrophysicist Neil deGrasse Tyson, director of New York's Hayden Planetarium, has even coined a name for this phenomenon: Manhattanhenge, after England's Stonehenge, the prehistoric circle of rocks that aligns with the rising sun at the summer solstice.
"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," deGrasse Tyson writes. "And the few times a year when the sun aligns with one of their stretches of road, all you get is stalled traffic (because) solar glare temporarily blinds drivers.
"Manhattanhenge," as coined by astrophysicist Neil deGrasse Tyson, occurred on May 29, 2014, in New York.
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"So, Manhattanhenge may just be a unique urban phenomenon in the world, if not the universe."
In past years the occurrence has drawn crowds to New York streets with especially good viewing angles -- which deGrasse Tyson identifies as 14th, 23rd, 34th, 42nd and 57th streets. He also recommends watching from the east side of Manhattan to get the full urban-canyon effect.
Sunset in New York is scheduled for 8:19 p.m. Friday and Saturday, with mostly clear skies -- although devoted Instagrammers will want to get in position earlier. (If it's cloudy, you're out of luck.)
Watch the sun align with Manhattan's street grid in a phenomenon called "Manhattanhenge."
As deGrasse Tyson points out, the sunset point creeps northward day to day along the horizon until the first day of summer, when it heads back southward until the first day of winter. The sun rises due east and sets due west only two days per year: on the equinoxes in spring and fall.
If Manhattan's street grid was perfectly aligned along north-south lines, then Manhattanhenge would coincide with the equinoxes. But Manhattan's layout is rotated 30 degrees east from geographic north, shifting the days of alignment to late May and mid-July.
After the sun's setting point turns southward, New York will get two more days of Manhattanhenge this year, on July 12 and 13.