Author: easyfilo

Enlarge (credit: Justin Lewis)

Medical authorities have spent years convincing people to use sunscreen to limit their exposure to UV light. But that effort has had a bit of a setback, as several locations have recently banned the use of sunblocks by beachgoers. Those bans took effect after local waters were found to have high levels of some of the chemicals in sunblock, which was associated with the lower health of nearby coral reefs.

Several studies have indicated that one specific sunblock component, a chemical called oxybenzone, is at the root of the problem. But the mechanism by which oxybenzone could harm corals wasn’t clear. And, without that understanding, it’s difficult to tell which sunblocks might pose a risk.

Now, researchers from Stanford University have identified the problem. The corals convert oxybenzone from a chemical that can harmlessly absorb UV light to one that damages biological molecules after being exposed to UV. And there’s evidence that coral bleaching makes matters worse, as the coral is less able to withstand exposure.

Enlarge (credit: Petro Zadorozhny | Getty Images)

In the snowy streets of the north Ukrainian town of Trostyanets, the Russian missile system fires rockets every second. Tanks and military vehicles are parked on either side of the blasting artillery system, positioned among houses and near the town’s railway system. The weapon is not working alone, though. Hovering tens of meters above it and recording the assault is a Ukrainian drone. The drone isn’t a sophisticated military system, but a small, commercial machine that anyone can buy.

Since Vladimir Putin invaded Ukraine at the end of February, drones of all shapes and sizes have been used by both sides in the conflict. At one end of the scale are large military drones that can be used for aerial surveillance and to attack targets on the ground. In contrast, small commercial drones can be flown by people without any specific training and carried around in a suitcase-sized box. While both types of drones have been used in previous conflicts, the current scale of small, commercial drone use in Ukraine is unprecedented.

Drone videos shared and posted to social media depict the brutality of the war and reveal what has happened during battles. Drones have captured fighting in the destroyed Ukrainian city of Bucha, with lines of tanks moving around streets and troops moving alongside them. Commercial drones have helped journalists document the sheer scale of destruction in Kyiv and Mariupol, flying over burnt-out buildings that have been reduced to rubble.

Enlarge / An amethyst may make a good metaphor for geology as a whole. (credit: Getty Images)

To outsiders, geology can seem as dull as a rock, with a lexicon just as opaque, but to insiders, it is a limitless source of wonder. Various authors have used different tools to crack open geology’s dull exterior to show non-geologists the sparkling wonders within: Robert Hazen used color; Jan Zalasiewicz used a pebble; and Richard Fortey used a railway journey, for example.

Marcia Bjornerud uses words to unlock the mysteries of geology the way a video game might use gems to unlock a new level to explore. Her new book is a buffet of bite-size chapters perfect for dipping in and out of, read in no particular order. Geopedia is structured like an encyclopedia to the extent that its topics are arranged alphabetically, but it’s written for enjoyment rather than as a mere fact-reference.

Bjornerud keeps the reading light even when serving up expanses of time and space, and she follows each geological ‘dish’ with a chaser of pointers to other entries that may be related, if only tangentially. After “Amethyst,” for example, she suggests “Kimberlite,” a diamond ore, and “Pedogenesis,” the process by which soil is made.