This is a picture of Pemba Island, one of the islands of Zanzibar, the semi-autonomous region of Tanzania, taken by ESA astronaut Andreas Mogensen from the International Space Station.

On the north-eastern corner of the island there is a mysterious looking structure which appears to have been carved into the ground. It did not show up on satellite pictures until 2022 and seemingly nothing could immediately explain the odd-shaped figure measuring about three by two kilometres.

Andreas reached out to his followers on social media and asked for help to solve this mystery. Soon, many good guesses came flooding in, from seaweed growing and making way for green energy production, to a new airport. One follower managed to piece together images from ESA’s Sentinel-2 satellite, seeing the construction of the shape take place from late 2022 into 2023.

After just six hours and many discussions on what exactly this structure was, the answer came from space enthusiast Riccardo Rossi on X, formerly known as Twitter: it is a new major construction of the Micheweni Free Economic Zone (FEZ). There will be residential buildings, schools, hotels, car parking and water supply facilities for a small city on the coast of Pemba Island. Riccardo provided the detailed plan for the area and deciphered the puzzle of Zanzibar.

Andreas was happy to learn that the mystery of Zanzibar had been solved and grateful for all the guesses and help from the community.

You can follow the last weeks of Andreas’s Huginn mission on Andreas’s social media channels.