The five blues of Goodnight Moon

We didn’t set out to do this study scientifically. We set out to settle a small argument. Two of our editors looked at the first-edition Goodnight Moon (Hurd, 1947) and disagreed on how many distinct blues were actually on the page. One said three. One said seven. Both were wrong. The answer is five.

The methodology was straightforward. We sourced a clean first edition from a private collector in Hudson, New York (thank you, Caroline). We removed the dust jacket, scanned each spread at 1200 dpi on a calibrated drum scanner, and ran the scans through a spectrophotometric analyzer normalized for paper age (the cream of 1947 Mead paper has yellowed by approximately Munsell value 2.1 over seventy-nine years; we corrected for this). We then clustered the blue pixels and cross-referenced the centroids against the Munsell Book of Color (1929 edition), which is what Hurd was using at Harper & Brothers in the late 1940s.

The five blues that emerged:

#0E1230 — “Night room”

The deepest color on the page. Used for: the great green room’s walls (yes — the wall color is technically a blue), the sky outside the window, and, in a few late spreads, the bedclothes. Hurd painted this with what was almost certainly Winsor & Newton’s “Indigo” with a touch of “Lamp Black” — a combination he favored throughout his career and which we’ve matched to the Munsell value 5PB 2/4.

Function: structural dark. This is the color that does the rhythm. Without it, the room doesn’t darken.

#1D3656 — “Window blue”

The frame around the window, the small details on the floor, the spines of the books on the shelf. Slightly warmer than the night room — a midtone that bridges the deepest dark to the moonglow. Hurd used a great deal of this color in the early-to-mid spreads.

Function: connective tissue. The window blue is what lets the eye travel from one dark area to another without losing track.

#3F608F — “Tired blue”

The bedclothes, the cat’s eye in the moonglow, the trim of the rug. A blue that has had life lived in it — not vibrant, not faded, just settled. This is the color of the page that says we have done bedtime many times. It’s also the color most contemporary picture books fail to find; it sits in a part of the spectrum that digital tools tend to push toward purple or push toward gray.

Function: emotional warmth. The tired blue is what makes the page feel inhabited.

#9DBFD9 — “Moonglow”

The light from the moon, the highlights on the cat, the soft edge around the lamp. Surprisingly cool — not a warm yellow at all. Hurd’s choice here is the one that gets the most arguments in the studio. Why a cool moonglow? Our best theory: it preserves the unity of the palette. A warm moonglow would compete with the green of the room and the red of the wallpaper. The cool moonglow lets those other colors do their own work without fighting.

Function: gentle relief. The moonglow is where the eye goes to rest between the deeper blues.

#E7F0F6 — “Negative space”

The “blue” that is almost a paper white — used for the brightest highlights on the moon, the edge of the page in the final spread, and the small reflective points in the window. Technically a blue. Functionally a paper.

Function: the closing breath. The negative space is what the page becomes as bedtime concludes.

What the palette tells us about Hurd

Three observations from the data:

1. Hurd used the same five blues across the entire book. No new blue introduced for any spread. The discipline is total. By contrast, contemporary picture books in the same genre frequently use thirty to fifty distinct hues in the same color family. This is not because Hurd lacked tools (the Munsell library at Harper had over a thousand patches). It’s because more blues would have made the book less coherent.

2. The proportion is fixed. Across all twenty-eight illustrated pages, the ratio of the five blues is remarkably stable: roughly 5:3:2:1:0.5 (night room : window blue : tired blue : moonglow : negative space). The deepest dark does most of the work. The lighter blues are accent.

3. The pages without blues are deliberate. Three spreads in the book contain no blue at all (the cover, the title page, and the all-text final spread). These are the only spreads where the rhythm pauses. The blue palette is the bedtime rhythm.

A small additional finding

We hadn’t expected this: the warm accent in Goodnight Moon is not a single color. It’s a rotating warm accent — the lamp on one page, the moon on another, the wallpaper red on a third, the green wall on a fourth. The eye never lands on the same warm spot twice. This is the part of the book that is doing the magic, and we don’t think we’d noticed it consciously before pulling the scans apart.

If you want to test this yourself, get any edition of Goodnight Moon, lay it flat, and trace the warmest point on each spread with a finger. The finger never lands twice in the same place. The page is leading the eye through a small slow tour of the room. By the last spread, the eye has visited every warm thing. There is nowhere left to look. The book closes.

— Theo Klein is a co-editor of Nightnight.art. Methodology details, raw spectrophotometric data, and the matched Munsell patches are available on request to the studio.