Toffee Planets hint at Earth’s cosmic rarity + GW sharks have heavy metals in blood

“Toffee Planets” Hint at Earth’s Cosmic Rarity

INTRO: It might not occur to us surface dwellers very often, but rocks can flow—more like the way exceedingly lethargic toothpaste would rather than water. Exposed to the extreme temperatures and pressures that reign in the hellish realms far below our feet, rocks can practically swim—slowly diving down and bobbing up through much of Earth’s subsurface.

For some rocky worlds around other stars, what is true for Earth’s innards may extend right up to the surface. Super Earths—sometimes rocky exoplanets that are bigger than our pale blue dot but smaller than massive ice giants such as Neptune—have comparatively strong gravitational fields. Thanks to this extreme gravity, some scientists suspect, rocks on such worlds would flow far closer to the surface.

This arrangement would mean rocks that snap, fracture and break might only be found in thin veneers on these exoplanets’ crust. If these rocky super Earths have thick, Venus-like atmospheres or are especially close to their parent star, they might exhibit no familiarly brittle geology at their surface at all. Instead, says Paul Byrne, a planetary scientist at North Carolina State University and lead author of a study on the Super Earths, their surface rocks would be strangely malleable over long timescales, flowing a bit like the stretchy, sugary confections on offer in any earthly candy shop.

Understandably, Byrne has dubbed such worlds “toffee planets.”

The research, presented at the 50th Lunar and Planetary Science Conference in the Woodlands, Tex., has yet to be peer-reviewed. That has not stopped Byrne’steam speculating on what its findings might mean for the myriad super Earths already discovered beyond our solar system. The most striking possibility is that super Earths might not be able to sustain plate tectonics—the drifting of continents and cycling of crustal rock that intimately shapes Earth. Without that process, you can say goodbye to the building of mountains, the creation of oceans and plenty of a planet’s volcanoes, and, just maybe, the evolution of complex life itself.

The science is already starting to stick in experts’ mind. “It’s a fascinating concept,” says Sara Seager, a professor of astrophysics and planetary science at the Massachusetts Institute of Technology. In exoplanetary science, “you rarely see anything new like this. The fact that they came up with something new, that, in itself, is impressive.” (MORE)

Great white sharks have ‘toxic’ heavy metals in their blood, study finds

EXCERPT: What do mercury, arsenic and lead have in common? If you guessed they’re all heavy metals, you’re right — at least, in part. These elements are also found in the blood of great white sharks, according to a recent study. Researchers with the University of Miami [...] determined these metals don’t adversely affect the sharks, at least in terms of their “body condition, total leukocytes and granulocyte to lymphocyte ratios,” per the University of Miami's news release on the findings, which were published in the Marine Pollution Bulletin in March.

[...] “As top predators, sharks bio-accumulate toxins in their tissues via the food web from the prey they eat. So by measuring concentrations of toxins, such as mercury and arsenic, in the blood of white sharks, they can act as 'ecosystem indicators' for the health of the ecosystem, with implications for humans," explained Neil Hammerschlag, a study co-author and research associate ... "Basically, if the sharks have high levels of toxins in their tissues, it is likely that species they eat below them will also have toxins, including fishes that humans eat,” he continued. (MORE - details)

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