How Colours Tell the Story of Earth | Colour: The Spectrum Of Science

Summary

Gold’s Journey and Concentration

Gold formed in distant stars and reached Earth in meteorite debris, after most of the planet’s metals had separated into its core. The gold added to Earth’s crust was extremely dilute. Over millions of years, geological processes and flowing water eroded, transported, sorted, and concentrated gold into deposits that people could find.

In streams, water flowing over ridges and crevices creates slower-moving areas where gold settles and becomes trapped. Prospectors can follow deposits upstream toward their source; smoother gold particles have generally travelled farther. These processes continue today.

Lapis Lazuli and Ultramarine

Lapis lazuli from Afghanistan was historically an exceptionally valuable blue pigment. Renaissance painters used it to display wealth, often depicting Mary’s robes in the colour. Crushing the rock releases its blue pigment, which becomes ultramarine paint when prepared with oil and wax.

The colour comes from sulfur combined with other elements in the rock. The programme notes that the conditions needed to produce such a striking colour involve the high pressures and temperatures associated with planetary formation.

Human Skin Colour and Ultraviolet Radiation

Melanin helps protect skin and DNA from ultraviolet (UV) radiation. In regions with high UV, darker pigmentation offers greater protection. In regions with low UV, lighter pigmentation helps the skin produce enough vitamin D, which is important for healthy bones and immune function. Human skin colour reflects this balance.

People with moderately or darkly pigmented skin may tan substantially, increasing pigmentation in sunnier seasons and losing it in winter. Because people now often live far from the regions where their ancestors evolved, they may need to manage sun exposure or take vitamin D supplements.

Colour Vision and Finding Food in Marmosets

The featured marmosets vary in their ability to distinguish red from green: all the males and about a third of the females are red-green colour-blind, while the remaining females have colour vision more like humans.

In a strawberry-finding test, the presenter took 1 minute 10 seconds with colour-blind-simulation glasses and 16 seconds with normal colour vision. Experiments with the monkeys found that all could complete the task given enough time, but those with human-like colour vision found ripe fruit faster—a potential advantage when food is scarce.

Infrared Astronomy Aboard SOFIA

The Stratospheric Observatory for Infrared Astronomy (SOFIA) was an aircraft carrying a telescope above much of the atmosphere’s water vapour. Infrared observations can reveal objects hidden by dust and gas, including the interiors of star-forming regions.

The programme compares this to radio signals travelling through a tunnel where GPS signals cannot.

Ultraviolet Vision in Birds

Starlings can see UV light because their eyes have UV-sensitive photoreceptors and lenses that let UV through. Some female feathers reflect UV, and the programme reports that UV-reflecting females tend to have larger broods and may be more attractive to males. This illustrates that animals experience visual information unavailable to humans.

Eagle Vision and the Limits of UV

The featured eagle has roughly twice the human ability to resolve fine detail. Although birds of prey can detect UV, the eagle’s lens filters out most of it. UV scatters more than longer wavelengths, which can reduce image clarity—a disadvantage when spotting small prey.

The programme also corrects the claim that raptors use UV-reflecting urine trails to locate mammals, describing that idea as unsupported. Humans likewise filter out UV, which helps protect the eye and preserve visual sharpness.

Researchers and Sources Featured

• Brent Shock — Prospector explaining how streams concentrate gold.
• David Margalis — Artist and historian discussing lapis lazuli and pigments.
• Nina — Researcher discussing human skin pigmentation and UV exposure; no surname is given in the subtitles.
• Andrew Smith — Zoologist at Anglia Ruskin University, studying colour vision in marmosets.
• Dr Jim Deiser — SOFIA science operations manager, explaining infrared astronomy.
• Professor Ron Douglas — Visual neuroscience professor at London City University, discussing bird vision.