 These pictures depict the magnificent wonders of our planet. Yet they weren't taken anywhere on Earth. Instead, they were captured by astronauts aboard the International Space Station to chronicle the fragile beauty and ever-changing landscape of our collective home. To date, over 4 million photos taken by humans from space have been collected. From the earliest days of the Mercury and Gemini missions to the ones taken aboard the space station, and all are freely available to researchers, scientists, and the public worldwide. These photographs are taken for many purposes, from artistic to the scientific, and have proven to have a wide range of uses. A powerful use of crew photography is to study changes to our planet over long periods of time. The Tashka Lakes and Lake Nasser in Egypt, for example, photographed on a regular basis from the station over the past 20 years. This is partially because the water levels in these lakes change dramatically on a month-to-month basis, constantly affecting agriculture in the region. Researchers, able to observe these bodies of water over a long period of time using crew photography, can ask, is their volume more or less stable over time? Or are they slowly losing their water? Andrea Wenzel is a geoscientist for the Earth Science and Remote Sensing Unit who managed requests for crew photography. She notes the flexibility that a crew member offers when taking a picture of Earth. A satellite generally takes the same photos over the same locations in the same orientation over and over. Astronauts, on the other hand, can use different lenses to take photos with different fields of view, from close-up to wide shots. The cupola on the bottom of the space station allows for a panoramic view straight down, or the crew members can elect to photograph an image that includes the horizon. And because the space station flies an asynchronous orbit around Earth, it can capture images at any time of day or night. Wenzel notes that the Vietnam Glacier at the southern end of South America is a good example of a moving Earth feature being observed by crew photography over time. There's been a significant decrease in the glacier's length over the years, and the photos allow researchers to observe the path the glacier is taking and correlate that to climate change data. The crew can also be asked to capture an event like a hurricane, wildfire, flood or volcanic eruption. This image shows flooding in Columbia. Wenzel says it was one of a series of photos that was used by international first responders to update their flood maps. As a result, they launched an operation to rescue the inhabitants of local villages who were stuck in place due to rising water. Astronauts often say the most remarkable thing about seeing Earth from the space station is viewing our planet across climate zones and continents without borders drawn on a map. Fortunately for those of us still on the ground, their photographic skills allow us to see what they see now and over decades of time, benefiting all of us in multiple ways.