Monday, July 13, 2015

Spectacular photos from space


NORTHWEST SARDINIA

This image over part of the Italian island of Sardinia comes from the very first acquisition by the Sentinel-2A satellite. Launched in the early hours of 23 June, the ‘color vision’ mission for Europe’s This image over part of the Italian island of Sardinia comes from the very first acquisition by the Sentinel-2A satellite. Launched in the early hours of 23 June, the ‘color vision’ mission for Europe’s Copernicus programme delivered its first image of Earth on 27 June, which covered a 290 km-wide strip from Sweden down to Algeria – including part of Sardinia. The area pictured covers a section of the island’s northwestern Sassari province, with parts of the coast visible along the left side and bottom. Agricultural fields dominate the inland, with a large area of vineyards at the center of the image. While the satellite mission will provide optical data for land monitoring, its main instrument has 13 spectral bands. This false-colour image was processed including the instrument’s near infrared spectral channel – which explains why plants in the area pictured appear red. The varying shades of red and other colours across the entire image indicate how sensitive the multispectral instrument is to differences in chlorophyll content. This is used to provide key information on plant health and, for this image, the brighter reds indicate healthier vegetation.

Like a ship plowing through cosmic seas, runaway star Zeta Ophiuchi produces the arcing interstellar bow wave or bow shock seen in this stunning infrared portrait. In the false-color view, bluish Zeta Oph, a star about 20 times more massive than the Sun, lies near the center of the frame, moving toward the left at 24 kilometers per second. Its strong stellar wind precedes it, compressing and heating the dusty interstellar material and shaping the curved shock front. Around it are clouds of relatively undisturbed material. What set this star in motion? Zeta Oph was likely once a member of a binary star system, its companion star was more massive and hence shorter lived. When the companion exploded as a supernova catastrophically losing mass, Zeta Oph was flung out of the system. About 460 light-years away, Zeta Oph is 65,000 times more luminous than the Sun and would be one of the brighter stars in the sky if it weren't surrounded by obscuring dust. The image spans about 1.5 degrees or 12 light-years at the estimated distance of Zeta Ophiuchi.

GREAT BARRIER REEF, AUSTRALIA

This satellite image takes us off the east coast of Australia where currents swirl in the water around corals.
This satellite image takes us off the east coast of Australia where currents swirl in the water around corals.The Great Barrier Reef is the world’s largest coral reef system. The reef’s diversity of life faces numerous threats such as climate change, pollution, fishing and outbreaks of the coral-preying crown-of-thorns starfish. Satellites offer the means to monitor the health reefs across the globe – as well as other parameters that indicate the overall health of oceans. Optical satellite imagery, like what we see here, can be used to monitor the ocean colour and detect harmful phytoplankton blooms. They can also help map the ocean floor at shallow depths.

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