A layer of charged particles, called the ionosphere, surrounds Earth, extending from about 50 to 360 miles above the surface of the planet – shown in purple and not-to-scale in this image. Because the ionosphere swells in response to incoming radiation from the sun, the exact size and shape of the ionosphere can change throughout the day, and the daytime ionosphere is always larger than the nighttime ionosphere. Image credit: NASA’s Goddard Space Flight Center/Duberstein

The Global-scale Observations of the Limb and Disk, or GOLD, instrument launches aboard a commercial communications satellite in January 2018 to provide the most comprehensive observations of the ionosphere we’ve ever had.