Monday, March 13, 2017

How Satellites Document Our Changing World

The satellite constellation of Earth-imaging company Planet Labs is able to provide a regular complete view of Earth at 3-5 m optical resolution. You can now explore these satellite images on their new Planet Explorer map.

Planet Explorer allows you to observe how the world has changed over the last year. Using the map's timeline you can zoom-in on any location on Earth and view the satellite imagery for any month, going back to January 2016. If you register with Planet Labs you can even view the daily updates to the satellite imagery in California.

Currently Planet Explorer has global satellite imagery at a resolution of 30 to 40 meters. The United States however is available at 3 to 5 meter resolution.

The Landsat program has been capturing satellite imagery of the Earth since the early 1970's. This means they now have access to over 40 years of satellite imagery, which is a wonderful resource for documenting changes to our planet.

Landsat Lens allows you to explore how the Earth has changed by comparing Lansat satellite imagery from six different years. The map allows you to search for any location on Earth and then overlay satellite imagery of your selected location from 1975, 1990, 2000, 2005, 2010 & 2015.

For example the screenshot above shows a map of the Aral Sea with four different satellite images from four different decades. Being able to directly compare the satellite images from different decades really helps to highlight the scale of how quickly the Aral Sea is disappearing.

You can also explore our ever changing world on Google's Timelapse map. Timelapse allows you to create a timelapse sequence from satellite images (from 1984 to 2012) for anywhere on Earth.The application comes with a number of default views that allow you to view timelapse animations of satellite images showing the sprawling growth of Las Vegas, the building of Dubai, the shrinking of the Mendenhall Glacier and the drying-up of Lake Urmia.

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