From Amber to White: How Earth’s Nighttime Glow Has Changed Over the Past 15 Years

From orbit, the Earth's nighttime signature is fading from amber to white. A series of photographs captured over 15 years by astronaut and photographer Don Pettit reveals a stark visual shift in the glow of global megacities, including Miami and Las Vegas. The world is losing its orange hue as municipalities replace traditional high-pressure sodium lamps with Light Emitting Diodes (LEDs). The color change is a result of fundamental physics. Sodium lamps operate on a narrow spectral band, emitting the warm, monochromatic yellow-orange light that defined city skylines for decades. LEDs, by contrast, produce a much broader spectrum of light, which appears as a sharp, cold white from space. This transition is driven by urban economics. LEDs are significantly more energy-efficient and possess a longer operational lifespan, reducing both electricity costs and the frequency of maintenance. Additionally, digital LED systems allow cities to dim or brighten lights remotely based on real-time traffic or time of day.