If you want to track changes in the Amazon rainforest, see the full expanse of a hurricane or figure out where people need help after a disaster, it’s much easier to do with the view from a satellite orbiting a few hundred miles above Earth.
Traditionally, access to satellite data has been limited to researchers and professionals with expertise in remote sensing and image processing. However, the increasing availability of open-access data from government satellites such as Landsat and Sentinel, and free cloud-computing resources such as Amazon Web Services, Google Earth Engine and Microsoft Planetary Computer, have made it possible for just about anyone to gain insight into environmental changes underway.
I work with geospatial big data as a professor. Here’s a quick tour of where you can find satellite images, plus some free, fairly simple tools that anyone can use to create time-lapse animations from satellite images.
For example, state and urban planners – or people considering a new home – can watch over time how rivers have moved, construction crept into wildland areas or a coastline eroded.
Landsat time-lapse animations show the river dynamics in Pucallpa, Peru.
Qiusheng Wu, NASA Landsat
A Landsat time-lapse shows the shoreline retreat in the Parc Natural del Delta, Spain.
Qiusheng Wu, NASA Landsat
Environmental groups can monitor deforestation, the effects of climate change on ecosystems, and how other human activities like irrigation are shrinking bodies of water like Central Asia’s Aral Sea. And disaster managers, aid groups, scientists and anyone interested can monitor natural disasters such as volcanic eruptions and wildfires.
GOES images show the decline of the crucial Colorado River reservoir Lake Mead since the 1980s and the growth of neighboring Las Vegas.
Qiusheng Wu, NOAA GOES
A GOES satellite time-lapse shows the Hunga Tonga volcanic eruption on Jan. 15, 2022.
Qiusheng Wu, NOAA GOES
Putting Landsat and Sentinel to work
There are over 8,000 satellites orbiting the Earth today. You can see a live map of them at keeptrack.space.
Some transmit and receive radio signals for communications. Others provide global positioning system (GPS) services for navigation. The ones we’re interested in are Earth observation satellites, which collect images of the Earth, day and night.
Landsat: The longest-running Earth satellite mission, Landsat, has been collecting imagery of the Earth since 1972. The latest satellite in the series, Landsat 9, was launched by NASA in September 2021.
In general, Landsat satellite data has a spatial resolution of about 100 feet (about 30 meters). If you think of pixels on a zoomed-in photo, each pixel would be 100 feet by 100 feet. Landsat has a temporal resolution of 16 days, meaning the same location on Earth is imaged…
