manhattanhenge

When Manhattan’s grid meets the setting sun

Manhattan’s streets miss true east–west by about 29°. But the sunset point drifts north and south along the horizon all year, and twice it lands right where the cross-streets point — the whole island, briefly, a sundial. The next alignment is Full Sun on the Grid, Saturday, July 11, 2026 at 8:20 PM EDT · in 21 days.

Find a wide cross-street and look west — the farther east you stand, the better.

Times are computed to the second from the sun’s motion, with the grid bearing measured from satellite imagery, and reconciled with the American Museum of Natural History’s published minutes — the full method is below.

By Ivar Vong

Sunset bearing

Jun 20

301.65° · 2.55° north of grid

GRID BEARING 299.1°

5th & 42nd

HUDSON RIVER

EAST RIVER

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Manhattan from above; the ray points to where the sun sets, seen from 5th & 42nd. The grid runs 29.1° north of true west. The ray locks amber the two times a year it lines up with the cross-streets.

Source: Sun positions from VSOP87 (Meeus). Grid azimuth 299.1° per AMNH Hayden Planetarium, confirmed by a five-canyon eyes-on-imagery survey (σ 0.019°). Observer: 5th Avenue at 42nd Street.

Solar day

NY-local · Saturday, June 20

Sunrise: 5:24 AM
Solar noon: 12:57 PM
Sunset: 8:30 PM

How the times are calculated

Three numbers, two events, four dates

Manhattanhenge happens when three things line up: the angle of Manhattan’s east–west streets, the height of the visible western horizon, and the size of the sun itself. Each is nearly fixed; the trick is when they meet.

299.1°

The grid bearing

Manhattan’s cross-streets run on this compass bearing. The Commissioners’ Plan of 1811 tilted the grid roughly 29° off true east–west; AMNH calibrated the exact value from the 42nd Street sightline.

0.5°

The horizon altitude

The apparent altitude AMNH publishes the half-sun against. Looking west across the Hudson, the visible horizon sits about half a degree above a flat-ocean one; each event is timed to the moment the sun reaches it.

0.27°

The sun's radius

The sun’s angular radius as it appears from Earth, just over a quarter of a degree. It’s also the altitude gap between the two named events: the disc climbs exactly one radius from half sun to full.

Each cycle has two named events. Half Sun on the Grid is the moment the sun’s center sits on the visible horizon — half the disc showing, the other half below. Full Sun on the Grid is the moment, the next day or the day before, when the whole disc has cleared the horizon, its bottom edge resting on it. Within a cycle the two fall on consecutive days; the order flips across the solstice — half then full in spring, full then half in July.

Why these two days, and not the next. The sun reaches Manhattan’s compass bearing — 299.1°, the angle the cross-streets run — every day in late May and again in early July. What changes from day to day is how high in the sky the sun is when it crosses that bearing. As the year approaches the summer solstice, it sits about a fifth of a degree higher each day. The two named days each cycle are the ones where that height lands in the narrow band between the visible horizon and the cornices that frame the cross-street.

The procedure: walk each day of the year forward in time. At some point in the afternoon the sun’s compass bearing reaches 299.1° on its way down toward the horizon. Look at how high the sun is in the sky at that moment. Keep the days when that height is closest to AMNH’s two published altitudes. Four dates a year.

Sun positions come from VSOP87, a mathematical theory of the solar system’s motion published in 1988 by the French astronomers Bretagnon and Francou. The numbers are cross-checked against DE440, the most precise modern ephemeris — a table of positions over time — maintained by NASA’s Jet Propulsion Laboratory. The two methods agree on the sun’s 2026 bearings to within 1.7 arcseconds, or about a thousandth of the moon’s apparent width. Refraction uses Saemundsson’s 1986 formula at standard atmosphere.

AMNH residual. The American Museum of Natural History publishes minute-precision times. Across the four 2026 dates, the engine’s second-precision values round up to AMNH’s published minutes: 8:13:16 → 8:14, 8:12:44 → 8:13, 8:19:46 → 8:20, 8:20:30 → 8:21. The match is consistent with a small convention difference — how the exact moment is defined, or how the time is rounded. Without AMNH’s internal calculation there is no way to say which, so the honest reading is agreement within one published minute.

The five canyons

Bearings, canyon lengths, and ROW widths come from an eyes-on-imagery survey: four pins per canyon (NW, SW, NE, SE) at the building corners that frame each canyon. All five canyon centerlines lie within 0.04° of the American Museum of Natural History’s published 299.1° (σ = 0.019°). The visibility window is how long the sun’s disc fits inside the canyon opening as it sweeps west.

2026 · alignments

Half Sun on the Grid
Thursday, May 28
8:13 PM EDT
Full Sun on the Grid
Friday, May 29
8:13 PM EDT
Full Sun on the Gridin 21 days
Saturday, July 11
8:20 PM EDT
Half Sun on the Grid
Sunday, July 12
8:21 PM EDT

Sun and moon positions from VSOP87 and ELP2000-82B (Meeus). Refraction via Saemundsson (1986) at standard atmosphere (10°C, 1010 mbar). Cross-validated against the American Museum of Natural History’s published times (within one minute) and against JPL’s DE440 ephemeris via Skyfield (sub-arcsecond, geometric). Observer: 5th Avenue at 42nd Street (40.7534°N, 73.9807°W), AMNH-canonical.

When Manhattan’s grid meets the setting sun

Three numbers, two events, four dates

42nd Street · 5th Avenue

57th Street · Park Avenue

34th Street · Park Avenue

23rd Street · 1st Avenue

14th Street · 1st Avenue