Today’s Image of the Day from NASA Earth Observatory features South Keeling, a remote, U-shaped atoll in the Indian Ocean made up of numerous coral islets. 

South Keeling stretches 11 miles from Horsburgh Island to South Island. Located 15 miles away is North Keeling – a smaller, uninhabited atoll. 

Astronaut image of South Keeling

The striking image of South Keeling was captured by astronauts aboard the International Space Station.

Astronaut photographs often highlight the varying depths of clear water. In this image, the shallow waters in the southern part of the lagoon appear light blue-green and can dry out during low water levels. 

In contrast, the deeper waters in the northern half, ranging from 26 to 46 feet, appear a darker shade of blue.

Cocos-Keeling Islands 

Together, North and South Keeling form the Cocos-Keeling Islands. They are situated about halfway between Australia and Sri Lanka.

The islands have been known as both Cocos and Keeling since the 1800s, with “Cocos” referring to the abundant coconut palm groves and “Keeling” honoring William Keeling, the first European to discover the islands in 1609. 

The combined name Cocos-Keeling Islands was officially adopted when the islands were incorporated into Australia in 1955.

Approximately 600 residents inhabit two of South Keeling’s islets. Bantam Village, the largest settlement, is situated on Home Island. 

The other populated island, West Island, is extensive enough to accommodate an airstrip, which is partially obscured by clouds in the image.

Significance of South Keeling

Historically, South Keeling has significant ties to Charles Darwin, who visited the islands in 1836 aboard the HMS Beagle. Bathymetric studies conducted during this voyage supported Darwin’s theories on atoll formation. 

South Keeling played a pivotal role in global communications during the early 20th century. In 1910, a telegraph cable station was established on Direction Island, positioning these remote islands as a crucial communication hub between Australia, Southeast Asia, and southern Africa before the First World War.

Charles Darwin’s famous expedition

Charles Darwin, the renowned naturalist, embarked on his famous journey aboard the HMS Beagle from 1831 to 1836. This expedition was crucial in shaping his theories on evolution and natural selection. 

Darwin’s observations of diverse species and geological formations, particularly in the Galápagos Islands, provided essential evidence for his groundbreaking work, “On the Origin of Species.” 

The voyage allowed Darwin to collect a vast array of specimens and data, contributing significantly to the scientific understanding of biodiversity and the processes driving natural variation.

Coral islets

Coral islets, also known as coral islands or cays, are small, low-elevation landforms formed primarily from coral detritus and associated organic material. 

These islets are typically found in tropical and subtropical regions, particularly within coral reef ecosystems. 

Coral islets form when fragments of coral and other marine organisms accumulate and consolidate over time, often on the reef’s crest or a submerged bank. 

They are characterized by their sandy or rocky composition and often support various plant and animal life, including specialized flora adapted to salty and nutrient-poor conditions. 

Image Credit: NASA Earth Observatory 

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