On the 40th anniversary of the famous ‘Blue Marble’ photograph taken of Earth from space, Planetary Collective presents a short film documenting astronauts’ life-changing stories of seeing the Earth from the outside – a perspective-altering experience often described as the Overview Effect.
One of the most stunning ISS timelapses yet.
Breathtaking composite series of images photographed from the Earth-orbiting International Space Station, approximately 240 miles above home.
Is Earth really a sort of giant living organism as the Gaia hypothesis predicts? A new discovery made at the University of Maryland may provide a key to answering this question. This key of sulfur could allow scientists to unlock heretofore hidden interactions between ocean organisms, atmosphere, and land — interactions that might provide evidence supporting this famous theory.
The Gaia hypothesis — first articulated by James Lovelock and Lynn Margulis in the 1970s — holds that Earth’s physical and biological processes are inextricably connected to form a self-regulating, essentially sentient, system.
One of the early predictions of this hypothesis was that there should be a sulfur compound made by organisms in the oceans that was stable enough against oxidation in water to allow its transfer to the air. Either the sulfur compound itself, or its atmospheric oxidation product, would have to return sulfur from the sea to the land surfaces. The most likely candidate for this role was deemed to be dimethylsulfide.
Newly published work done at the University of Maryland by first author Harry Oduro, together with UMD geochemist James Farquhar and marine biologist Kathryn Van Alstyne of Western Washington University, provides a tool for tracing and measuring the movement of sulfur through ocean organisms, the atmosphere and the land in ways that may help prove or disprove the controversial Gaia theory. Their study appears in this week’s Online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).
According to Oduro and his colleagues, this work presents the first direct measurements of the isotopic composition of dimethylsulfide and of its precursor dimethylsulfoniopropionate. These measurements reveal differences in the isotope ratios of these two sulfur compounds that are produced by macroalga and phytoplankton. These measurements (1) are linked to the compounds’ metabolism by these ocean organisms and (2) carry implications for tracking dimethylsulfide emissions from the ocean to the atmosphere.
Sulfur, the tenth most abundant element in the universe, is part of many inorganic and organic compounds. Sulfur cycles sulfur through the land, atmosphere and living things and plays critical roles in both climate and in the health of organisms and ecosystems.
“Dimethylsulfide emissions play a role in climate regulation through transformation to aerosols that are thought to influence the Earth’s radiation balance,” says Oduro, who conducted the research while completing a Ph.D. in geology & earth system sciences at Maryland and now is a postdoctoral fellow at the Massachusetts Institute of Technology. “We show that differences in isotopic composition of dimethylsulfide may vary in ways that will help us to refine estimates of its emission into the atmosphere and of its cycling in the oceans.”
As with many other chemical elements, sulfur consists of different isotopes. All isotopes of an element are characterized by having the same number of electrons and protons but different numbers of neutrons. Therefore, isotopes of an element are characterized by identical chemical properties, but different mass and nuclear properties. As a result, it can be possible for scientists to use unique combinations of an element’s radioactive isotopes as isotopic signatures through which compounds with that element can be traced.
“What Harry did in this research was to devise a way to isolate and measure the sulfur isotopic composition of these two sulfur compounds,” says Farquhar, a professor in the University of Maryland’s department of geology. “This was a very difficult measurement to do right, and his measurements revealed an unexpected variability in an isotopic signal that appears to be related to the way the sulfur is metabolized.
“Harry’s work establishes that we should expect to see variability in the sulfur isotope signatures of these compounds in the oceans under different environmental conditions and for different organisms. I think this will ultimately be very important for using isotopes to trace the cycling of these compounds in the surface oceans as well as the flux of dimethylsulfide to the atmosphere. The ability to do this could help us answer important climate questions, and ultimately better predict climate changes. And it may even help us to better trace connections between dimethylsulfide emissions and sulfate aerosols, ultimately testing a coupling in the Gaia hypothesis,” Farquhar says.
(via Science Daily)
Envisat ASAR image of the McClure Strait in the Canadian Arctic Archipelago, acquired on Aug. 31, 2007. The McClure Strait is the most direct route of the Northwest Passage and has been fully open since early August 2007.
At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured above, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an “untethered space walk” during Space Shuttle mission 41-B in 1984.
ISS Cometrise Time Lapse
A retinal flash of beauty seen aboard the ISS unlike any other from the newly discovered Comet Lovejoy.
Ocean Sand, Bahamas – Image taken by the Enhanced Thematic Mapper plus (ETM+) instrument aboard the Landsat 7 satellite. Tides and ocean currents in the Bahamas sculpted the sand and seaweed beds into these multicolored, fluted patterns in much the same way that winds sculpted the vast sand dunes in the Sahara Desert. Gorgeous!
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