Red and orange are two vibrant colors that compliment each other well. But what exactly causes the shift from red to orange? The transition has to do with wavelength and energy.
The Color Spectrum
The visible color spectrum that humans can see ranges from violet to red. Violet has the shortest wavelength at around 380-450 nanometers, while red has the longest wavelength at around 620-750 nm. Orange falls between red and yellow at 585-620 nm. When wavelength increases, energy decreases. This means violet has the most energy and red has the least energy.
Colors are determined by the wavelength of visible light. Objects appear a certain color because they absorb some wavelengths and reflect others. For example, a banana appears yellow because it absorbs blues and reflects greens and reds.
What Gives Red its Color?
The red color we see is the longest wavelength of light that our eyes can detect. Red objects reflect red wavelengths and absorb other colors. Red pigments get their color from chemicals such as anthocyanin, lycopene, carotene, and astaxanthin. Blood is red due to the iron-containing protein hemoglobin. Rubies contain the mineral chromium which causes the red color.
Shifting Towards Orange
So what causes red to shift towards orange? The transition occurs when red starts absorbing more blue light and reflecting more yellow and green wavelengths. This reduces the energy slightly, making the color more orange than red. Even a small change in wavelength can produce a noticeably different shade.
Mixing red and yellow paint or light will also make orange. Primary pigment colors are cyan, magenta, and yellow. The absence of cyan from magenta yields red, while adding some yellow shifts it towards orange. With light, red and yellow combine to make orange.
Why Do Leaves Change from Red to Orange?
Leaves provide a great example of red shifting to orange in nature. In the fall, cooling temperatures cause the green chlorophyll in leaves to break down. This reveals the other pigments that were masked by chlorophyll.
Leaves may turn yellow, orange, red, or brown depending on their pigments. The main pigments are:
- Carotenoids – Cause yellow and orange colors
- Anthocyanins – Cause red colors
- Tannins – Cause brown colors
Leaves that are red early in the season shift towards orange as more carotenoids are revealed. The balance of pigments in a leaf determines whether it ends up red or orange. Wet autumns can result in more red leaves, while drought leads to more orange leaves.
Factors that Shift Red to Orange
Here are some key factors that can turn a red color to be more orange:
- Absorbing more blue light and reflecting more yellow/green wavelengths
- Subtracting the cyan component from magenta pigment
- Mixing red and yellow light or paint
- The breakdown of chlorophyll revealing carotenoid pigments
- A balance of anthocyanin and carotenoid pigments
Examples of Red Shifting to Orange
| Item | Starts Red | Shifts Orange |
|---|---|---|
| Leaves | Early autumn | Later when carotenoids revealed |
| Cardinal | Male feathers | Female feathers |
| Cranberries | Unripe | Ripe |
| Lobster | Cooked | Overcooked |
| Sunset | Dusk | Further twilight |
This table shows several examples of red shifting towards orange in nature, foods, and the sky.
Conclusion
Red transitions to orange when the wavelength increases slightly and blue light is absorbed. Mixing red with yellow, revealing carotenoid pigments, and the balance of anthocyanins and carotenoids can all turn red to orange. This shift is visible in many fall leaves, cooked foods, feathers, skies, and more. Understanding the light spectrum helps explain how the eye perceives these subtle color changes.
