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SYFY WIRE Bad Astronomy

Earth’s Sentinel

By Phil Plait

The European Space Agency is serious about monitoring our environment.

Their Copernicus Program is an ambitious, long-term effort to study our planet and understand its changing ways. The most recent addition to this program is the Sentinel-3 satellite series, three Earth-observing birds that will monitor our world with an impressive suite of instruments.

The first of the three, Sentinel-3A, launched into orbit on Feb. 16 and is already returning devastatingly beautiful images of Earth. Check. This. Out.

I love this shot! It shows dusk over Svalbard, Norway, the day-night line (called the terminator) sweeping across the frozen region. There’s a snowy archipelago, sea ice, and a few thin twilight clouds barely lit by the setting Sun.

I love the color, but, frustratingly, I can’t tell you if it’s natural color (that is, what our eyes see) or not. That information was not in the press release, nor the images themselves. All the images I have here were taken with the Ocean and Land Colour Instrument, a workhorse camera that can take observations from the blue part of the spectrum out to the near-infrared (separated into 21 separate colors). It’s a pushbroom-style camera, and can see a swath of Earth up to 1,270 kilometers across.

This (probable natural color) shot shows the Strait of Gibraltar, with Spain to the north and Morocco to the south. I had to shrink and crop this to get it to fit on the blog, so please take a look at the full-frame image, because yikes. You can see altocumulus clouds over the Atlantic, phytoplankton blooms off the coasts of both continents, and so much more. The detail is stunning.

Finally, and more familiar to North Americans, here is the Gulf of California, which separates the peninsula of Baja California from the mainland of Mexico. Look at those clouds off the coast, as well as farther inland! Again, the resolution is phenomenal.

Sentinel’s mission is multiplex; it will monitor colors of the Earth to look for environmental changes, measure atmospheric and ocean temperatures, monitor sea ice, investigate marine ecosystems, and keep an eye on water quality as well. And that’s just a taste; there’s much more. Of course, it will also be critical in investigating the effects of climate change on land and in the oceans.

Like I said, ESA is serious about studying our environment. I’m glad they are; it’s a big, complex planet, and the more countries and scientists we have studying it, the better off we’ll all be. Assuming we take the data seriously.

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