Galapagos Islands

Credit: ESA, Posted on: Friday, 30 January 2009, 06:52 CST Download full size image

This Envisat image features the Galapagos Islands, an archipelago situated some 1 000 km to the west of Ecuador in the Pacific Ocean.

The islands were formed by volcanic activity around 10 million years ago. Out of the 19 islands, two are still active volcanoes.

Due to the isolation of the islands, a very unique ecosystem developed and many of the species found there exist nowhere else on Earth. All reptiles, half of the plants and some 40% of the birds are endemic.

A national park has been established to protect the island’s unique habitat and to ensure the survival of the endangered species.

Discovered in 1535, the islands became famous in the early 19th century when English scientist Charles Darwin wrote ‘The origin of species’ based on his observations made on Galapagos.

Galapagos’s largest island is Isabela (visible). The five volcanoes seen on the island are (from north to south): Wolf Volcano, Darwin Volcano, Alcedo Volcano, Sierra Negra Volcano and Cerro Azul Volcano. The bigger island to the right of Isabela is Santiago Island.

Apart from mapping changes on the land surface, radar data can also be used to determine sea surface parameters like wind speed, wind direction and wave height. Different wave types and wind speeds are visible in the image as ripples on the water surface.

The image was obtained by combining three Advanced Synthetic Aperture Radar (ASAR) acquisitions (23 March 2006, 14 August 2008 and 1 January 2009) taken over the same area. The colours in the image result from variations in the surface that occurred between acquisitions.

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