An astronaut on the International Space Station captured this image of a late summer plankton bloom across much of Lake Ontario, on the U.S. Great Lakes, on August 24, 2013. The greenish color is due to microscopic cyanobacteria, or blue-green algae, which can become so dense in the water, and color it so vividly, that the change is visible from orbit. NASA said:
Harmful algal blooms, or HABs, have been observed in all of the Great Lakes — particularly Lake Erie — and are caused by a variety of factors, including: changes in precipitation; drought; invasive species (quagga, zebra mussels, Asian carp); nutrient loading from runoff and sewage (nitrogen and phosphorus); and warmer-than-average temperatures …
Astronaut photograph ISS036-E-35635 was acquired on August 24, 2013, with a Nikon D3S digital camera using a 50 millimeter lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 36 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.