Dazzling photographs and images from space of our planet's nightlights have captivated public attention for decades. In such images, patterns are immediately seen based on the presence or absence of light: a distinct coastline, bodies of water recognizable by their dark silhouettes, and the faint tendrils of roads and highways emanating from the brilliant blobs of light that are our modern, well-lit cities. For nearly 25 years, satellite images of Earth at night have served as a fundamental research tool, while also stoking public curiosity. These images paint an expansive and revealing picture, showing how humans have illuminated and shaped the planet in profound ways since the invention of the light bulb 140 years ago.

The National Aeronautics and Space Administration (NASA) is an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research.