Submerged sandbars glow like underwater aurora in the Bahamas as seen by astronauts — Earth from space
QUICK FACTS
Where is he? Carter’s Cays and Strangers Cay, Bahamas [27.105580266, -78.06669135]
What’s in the photo? Underwater sandbanks and coral reef surrounding two small islands
Who took the photo? An anonymous astronaut on the International Space Station (ISS)
When was it taken? October 20, 2016
This intriguing astronaut photo shows a series of undulating sandbars surrounding two small islands in the Bahamas. The submerged whirlpools were partly carved out by a coral reef lurking at the edge of a hidden ocean “drop-off”.
This photo shows a series of complex sandbars and a shallow barrier-like coral reef in the waters surrounding two small islands: Carter’s Cays (lower left) and Strangers Cay (upper right). The islands are two of the northernmost landmasses in the Bahamas, located approximately 200 kilometers east of Florida. (For context, Strangers Cay is approximately 2.2 miles (3.6 km) in diameter at its widest point.)
The sandbars, which can be seen wrapping in and around the two cays like ribbons, have been sculpted by decades of unchanged ocean currents, causing sand to accumulate in one place over time.
But the coral reef – which runs across the lower right corner of the image and whose waves break on its far edge – is much older, probably having been built over several millennia.
The largest and most prominent sandbar, which looks like a giant U in the center of the image, lies directly in front of a large break in the coral reef. It’s no coincidence: The reef break created a strong, sustained tidal current that pushed the sand much farther back, according to the Earth Observatory.
These sand swirls are quite small compared to some of the larger sandbars in the area. The biggest is the Bank of Grand Bahamawhich covers an area of approximately 80,000 square miles (210,000 square kilometers) off the coast of the Exuma Islands in the central Bahamas and is home to a huge seagrass ecosystem.
These characteristics frequently attract comparisons with abstract paintings or the Northern Lightsbecause of their shape and captivating brilliance when viewed from above. However, their supposed brightness is actually just an optical illusion caused by their proximity to the ocean surface. In some areas, the sand is probably only about 2 meters below the waves, according to the Earth Observatory.
If you look closely at the ocean surface in the image, you’ll also notice that the water at the top left of the islands is very clear and covered in shimmering streaks, while the bottom right corner of the image – beyond the reef – is darker and features traditional wave patterns.
This is the result of a steep drop into the depths of the ocean just beyond the coral reef, similar to that depicted in the movie “Finding Nemo.” Beyond this point, ocean currents create the waves that many people see from an airplane window. But behind the reef, the wind sculpts the ocean surface into subtle streaks.
This difference in altitude also explains why there are no sandbars visible beyond the reef.
For more incredible satellite photos and astronaut images, check out our Earth seen from space archives.
