Things You Thought You Knew - The Color of the Sun - StarTalk Radio Recap

Podcast: StarTalk Radio

Published: 2025-12-30

Duration: 48 min

Summary

The episode debunks common misconceptions about the color of the sun, explaining that the sun is actually white rather than yellow. It also explores how atmospheric conditions affect the perception of the sun's color.

What Happened

Neil deGrasse Tyson and Chuck Nice break down the science behind why the sun is perceived as yellow when it's actually white. They explain that as the sun's light passes through Earth's atmosphere, it scatters blue light, leaving behind a spectrum that appears yellow to the human eye, especially when it's low on the horizon during sunrise or sunset.

The hosts dive into the concept of atmospheric scattering and how it affects the colors we perceive in the sky. They discuss the role of Isaac Newton's discovery of the spectrum of light, which shows that sunlight is a mixture of all colors, perceived as white.

They explain how the thickness of the atmosphere changes the path of sunlight, leading to more scattering and a shift in the perceived color of the sun from white to yellow, orange, or red at different times of the day.

The conversation shifts to how snow reflects all colors of light, thereby appearing white, which further proves that the sun is white because if it were yellow, snow would look yellow under sunlight.

The hosts also talk about different acoustic phenomena related to weather, such as the sound of thunder being a result of lightning's shockwave, and how the temperature and composition of the atmosphere can affect the sound of snow crunching underfoot.

Neil deGrasse Tyson and Chuck Nice explore how friction is often misunderstood, explaining its crucial role in everyday activities like walking and driving, and how it is essential for the function of rockets and spacecraft.

Finally, they introduce the concept of aerobraking, illustrating how spacecraft use the friction of Earth's atmosphere to slow down upon re-entry, converting kinetic energy into heat as a form of braking without the need for extra fuel.

Key Insights

• The sun appears yellow to the human eye due to atmospheric scattering, which filters out blue light and leaves a spectrum that looks yellow, especially when the sun is low on the horizon.
• Isaac Newton's discovery of the light spectrum revealed that sunlight is a mixture of all colors, which combine to appear white, contradicting the common perception of the sun as yellow.
• The color of snow appears white because it reflects all colors of light; if the sun were truly yellow, snow would appear yellow under sunlight.
• Aerobraking is a technique used by spacecraft to slow down upon re-entry by using Earth's atmosphere to convert kinetic energy into heat, eliminating the need for additional fuel.