The Japanese custom of momijigari, or “purple leaf looking,” stretches again greater than a millennium, as evidenced by historical poems describing journeys to admire fall foliage. In America, mentions of foliage journeys started showing within the historic file within the 19th century, across the time artists and poets reminiscent of Frederic Church and Emily Dickinson celebrated autumn colour in depictions of the Northeast.
Fashionable-day leaf peepers have a brand new strategy to observe and savor the seasonal phenomenon. The hyperspectral OCI (Ocean Shade Instrument) on NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) satellite tv for pc observes the planet’s oceans and vegetation every day at 286 spectral bands. Amongst this array are a couple of teams of wavelengths that enable scientists to trace refined modifications in leaf pigments key to fall foliage shows, together with anthocyanins (reds), carotenoids (yellows and oranges), and chlorophylls (greens).
NASA scientists can observe fall colour by measuring how a lot purple, orange, and yellow forests present in contrast with inexperienced. Monitoring the ratio over time reveals the place leaves are altering and when colour peaks. The maps above present vegetation “redness” from September 29 to October 4 (left) and October 5 to 11 (proper). Areas proven in inexperienced have values close to 1, that means the satellite tv for pc detects about as a lot purple as inexperienced, and most leaves haven’t but turned. Areas proven in gentle yellow and purple have greater values, indicating progressively extra purple pigment relative to inexperienced.
The satellite tv for pc detected notably excessive ranges of redness in elements of northern and jap Russia, northern Alaska, and northern Canada from September 29 to October 4. In New England and upstate New York, redness started to fade in the course of the week of October 5 to 11, even because it unfold throughout a lot of the Midwest and the Mid-Atlantic. (Not all of the yellows and reds on the maps characterize fall colours. Crops in some agricultural areas, as an illustration, present excessive anthocyanin ranges as they age and after they’re harvested. Additionally, in some areas, clouds produce what look like gaps within the vegetation.)
Lots of the reddest areas—such because the Adirondacks in New York, the Inexperienced Mountains in Vermont, and the White Mountains in New Hampshire—have massive numbers of sugar maples (Acer saccharum) and purple maples (Acer rubrum), deciduous timber that flip a superb shade of crimson within the fall. Blueberries, bilberries, sedges, mosses, and grasses doubtless contribute to the extraordinary reds detected in marshy tundra areas in northern Alaska, Canada, and Russia.
The OLI (Operational Land Imager) on Landsat 9 captured a picture (above) of intensely purple foliage round Ripton, Vermont, on October 3, 2026, across the peak of redness within the area. Poet Robert Frost, creator of “October,” “The Highway Not Taken,” “Nothing Gold Can Keep,” and several other different poems that evoke fall foliage, stored a summer season residence and farm in Ripton and taught at Middlebury’s Bread Loaf Faculty of English.
Another satellites with hyperspectral sensors can measure fall foliage pigments in a method that’s much like PACE, however solely in additional localized areas and fewer ceaselessly. PACE is the primary satellite tv for pc able to measuring all three key leaf pigments—anthocyanins, carotenoids, and chlorophylls—throughout your complete planet on daily basis or two.
“It is the flexibility to gather time-series knowledge of anthocyanins and carotenoids in all places on Earth repeatedly that’s game-changing,” mentioned Karl Huemmrich, a vegetation scientist with the Goddard Earth Sciences Know-how and Analysis II middle on the College of Maryland, Baltimore County. Huemmrich, who can be a member of the PACE science workforce, was desirous to work with the satellite tv for pc due to OCI’s broad swath and brief revisit time. “The time-series knowledge enable us to find out peak redness and yellowness wherever on Earth,” he mentioned.
Within the fall, leaves change colours as they lose chlorophyll, a inexperienced molecule that crops use to synthesize meals. Since chlorophyll isn’t a secure compound, crops should repeatedly synthesize it, a course of that requires ample daylight and heat temperatures. As temperatures lower and days shorten in autumn, ranges of chlorophyll drop, inflicting greens to fade and presenting a chance for carotenoids and anthocyanins to point out their colours.
As a part of the continuing North American Phenology Marketing campaign run by the World Studying and Observations to Profit the Atmosphere (GLOBE) program, NASA knowledge scientist Skye Caplan has been posting weekly foliage maps of vegetation redness. The maps present waves of purple rising within the excessive latitudes in August and shifting equatorward in September and October. The PACE workforce is asking the general public to submit pictures of fall foliage to assist scientists “floor reality” the satellite tv for pc observations and higher perceive how numerous elements affect vegetation colour.
“Adjustments in pigments may happen when vegetation is burdened attributable to drought or insect injury,” mentioned Caplan. She famous that modifications like these doubtless assist clarify why PACE measures excessive ranges of redness in agricultural areas of Brazil, Australia, and Canada that do not observe carefully with broader seasonal modifications.
“The extra pictures we are able to get from the bottom, the higher,” Caplan mentioned. Floor pictures assist scientists refine PACE’s observations of vegetation colour, which the workforce hopes will ultimately assist a number of traces of analysis. These embrace how the timing of spring greening and fall senescence is altering, how vegetation modifications have an effect on the worldwide carbon cycle, and the way leaf colour influences wildfire danger. Scientists additionally wish to know whether or not PACE can detect early warning indicators of drought, insect infestations, and plant illness.
Folks can take part within the GLOBE marketing campaign even when they reside in an space with out dense forests or picturesque fall foliage shows. Scientists additionally need floor observations of shrubs, grasses, wildflowers, evergreens, crops, and different vegetation. However in the case of “purple leaf looking,” do not delay, Caplan mentioned. “Shade modifications occur form of slowly, then abruptly, after which they’re gone.”
NASA Earth Observatory photographs by Lauren Dauphin, utilizing PACE knowledge courtesy of Skye Caplan/NASA’s Goddard Area Flight Heart and Landsat knowledge from the U.S. Geological Survey. Picture courtesy of the GLOBE Program. Story by Adam Voiland.
September 29 – October 4, 2026
October 5 – October 11, 2026
Landsat 9: October 3, 2026
- Caplan, S. & Huemmrich, F. (2025) Unveiling PACE OCI’s hyperspectral terrestrial knowledge merchandise. Distant Sensing Letters, 16(4), 422-433.
- GLOBE Program (2026, October 18) PACE Fall Foliage Updates. Accessed October 22, 2026.
- GLOBE Program (2026) North America Phenology Marketing campaign. Accessed October 22, 2026.
- GLOBE Program (2026, September 22) Monitoring Fall Shade with PACE. Accessed October 22, 2026.
- Huemmrich, Okay. et al. (2026) Observing fall foliage with PACE pigment indices. Distant Sensing Letters, 17(6), 853-863.
- Psychological Floss (2024, August 20) A Transient Historical past of Leaf-Peeping. Accessed October 22, 2026.
- NASA Scientific Visualization Studio (2025) World Views of PACE Land Vegetation Information. Accessed October 22, 2026.
- UMBC (2026, June 12) For the leaf peepers: How NASA’s PACE is bettering fall colour forecast. Accessed October 22, 2026.
- Veltra (2025) Autumn in Japan: The Cultural Which means of Kōyō (紅葉) & Momijigari. Accessed October 22, 2026.