Must Read: Ocean Color, Ocean Beauty - Southern Africa, Madagascar and Indian Ocean

Forty-five years ago this week, Americans celebrated the first Earth Day. Sixteen years ago, on April 29, 1999, the NASA Earth Observatory was launched on the World Wide Web. Both the holiday and the web site celebrate awareness of our planet, its power, and its fragility. They also celebrate the simple beauty of the place we call home.

Today’s image captures some of that beauty. This natural-color composite image of Earth was assembled from data acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (Suomi-NPP) spacecraft. It stitches together 671, 551, and 443 nanometer wavelength data from six orbits on April 9, 2015.

Suomi NPP does not actually observe Earth from the perspective shown in this image. The satellite flies in a polar orbit at an altitude of 824 kilometers (512 miles), and its images have a resolution of 375 meters per pixel. (Click here for an example of an individual NPP image.) In the image above, the virtual camera looks down from the perspective of 8,300 kilometers (5,100 miles) above a point at 50 degrees South latitude and 40 degrees East longitude.

This composite image emphasizes the blue in our Blue Marble. Most of the scene is filled by the Indian Ocean (center and left), while parcels of the Atlantic (top left) and Southern Ocean (bottom) fill in the rest and remind us that it is all really one ocean. The image also includes southern Africa and Madagascar, with tropical cyclone Joalene swirling in the Indian Ocean.

NASA image by Norman Kuring, NASA’s Ocean Biology Processing Group using Suomi NPP data. Suomi NPP is the result of a partnership between NASA, NOAA and the Department of Defense. Caption by Mike Carlowicz.

Instrument(s): 

Suomi NPP - VIIRS

Plumes From #Africa ’s Volcanic Duo #Volcano

Located near the equator in central Africa, the Nyamuragira and Nyiragongo volcanoes are often obscured from satellite view by clouds. But on February 9, 2015, clear skies afforded an unobstructed view from space of two plumes venting from the volcanic duo in the Democratic Republic of the Congo.
The natural-color images above were acquired by the Operational Land Imager (OLI) on Landsat 8. The top image shows a broad view of the region, with Nyamuragira to the north and Nyiragongo to the south.
The second image shows a close-up view of Nyamuragira, Africa’s most active volcano. Nyamuragira is a shield volcano composed of old lava flows that cover about 1,500 square kilometers (580 square miles). The slopes of this broad volcano rise gradually, reaching an altitude of 3,058 meters (10,033 feet).
The volcano is topped with a small caldera with walls about 100 meters (330 feet) high. In 1938, a lava lake within the caldera drained during a large, long-lasting fissure eruption that sent lava flows all the way to Lake Kivu. Satellite observations and helicopter overflights confirmed in 2014 that the caldera again contains a small but vigorous lava lake.
The third image shows a close-up of Nyiragongo, another highly active volcano just 15 kilometers (9 miles) southeast of its northern sibling. In contrast to Nyamuragira’s relatively gentle slopes, Nyiragongo is a steep-sloped structure composed of alternating layers of solidified ash, hardened lava, and rocks ejected by previous eruptions. Its caldera also holds molten lava, which as of 2014 was the largest-known lava lake on Earth.
Occasionally, Nyiragongo spews more than just steam and volcanic gases. Eruptions of fluid lava from the volcano in 1977 and 2002 had deadly consequences for the city of Goma, which lies about 15 kilometers (9 miles) south of the volcano.

• References and Related Reading

• Campion, R. (2014, November 7) New lava lake at Nyamuragira volcano revealed by combined ASTER and OMI SO2 measurements. Geophysical Research Letters, 41 (21), 7485-7492.
• NASA Earth Observatory (2014, June 30) Nyamuragira Volcano Erupts. Accessed February 13, 2015.
• NASA Earth Observatory (2007, May 8) Nyiragongo Vents Steam. Accessed February 13, 2015.
• NASA Earth Observatory (2007, December 10) Nyamuragira and Nyiragongo. Accessed February 13, 2015.
• Smithsonian Institution Global Volcanism Program (2014) Nyiragongo. Accessed February 13, 2015.
• Smithsonian Institution Global Volcanism Program (2014) Nyamuragira. Accessed February 13, 2015.

NASA Earth Observatory images by Jesse Allen, using Landsat data from the U.S. Geological Survey.

Instrument(s): 

Landsat 8 - OLI - NASA