A Bizarre ‘Ice Circle’ Is Turning Heads in Maine. Here’s the Science Behind It

Nature loves to make things round: planets, soap bubbles, oranges, eyeballs, the circular swirl of a spinning hurricane. A lot of forces are at play in favoring natural circles and spheres—the equalizing force of air pressure pushing out or gravity pulling in; the rotation of the Earth, creating vortices in air; the evolutionary imperative of efficient packaging.

The power of the round is in the news again, with the appearance of a massive, rotating ice disk in the Presumpscot River in Westbrook, Maine. The disk was first noticed on January 14, spinning in a lazy, counterclockwise direction. On social media, the ice circle was an instant sensation, alternately said to resemble a British crop circle or the mottled face of the moon—both fair descriptions. Either way, the Presumpscot ducks loved it, settling down for a slow-motion ride as the sights of Westbrook passed before them.

Ice circles are rare but hardly unheard of. What makes this one special is its size: 300 ft. in diameter, or 10 times bigger than the common 30-footers.

Big or small, all ice circles are formed by the same laws of physics. Random eddies in water will generally follow a circular route—the rotation of the Earth again—moving more slowly than the overall, downstream current. Bits of ice become trapped in the vortex and, since slower water is less turbulent than faster water, more ice is able to form and accumulate, eventually accreting into a sheet. As the sheet turns, it bumps up against the shore or other chunks of ice and is, in effect, lathed down until it is round.

River currents aren’t the only factor that contributes to the rotation of an ice disk. A 2016 experiment at the University of Liége in Belgium recreated an ice disk in the lab, finding that as temperatures rise a bit and ice from the edges begins to melt, the water it releases sinks and creates a gentle vortex of its own, which also imparts a spin to the ice floating above it.

Ice disks, of course, are fleeting things—longer-lived than the soap bubble, shorter-lived than a planet—vanishing entirely as the seasons change. It takes one more circle, the Earth’s revolution around the sun, to summon up another winter before they return.

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Source:: Time – Science


China Grows the First Seed on the Moon

The moon is an inhospitable place. In the sunlight, temperatures hit highs of 260 degrees Fahrenheit, in the dark, it can reach a miserable minus 280. Radiation is high and water is scarce. But according to the China National Space Administration, there is now life growing 240,000 miles from the Earth; cotton seeds carried on board the Chang’e-4 lunar lander have just sprouted, making them the first plants to ever germinate on another world.

“We have given consideration to future survival in space. Learning about these plants’ growth in a low-gravity environment would allow us to lay the foundation for our future establishment of space base,” Liu told the South China Morning Post. The Chinese Communist Party’s official newspaper, The People’s Daily hailed the achievement as “humankind’s first biological experiment on the moon”.

First in human history: A cotton seed brought to the moon by China’s Chang’e 4 probe has sprouted, the latest test photo has shown, marking the completion of humankind’s first biological experiment on the moon pic.twitter.com/CSSbgEoZmC

— People’s Daily, China (@PDChina) January 15, 2019

Chang’e-4 was launched in early December from the Xichang Satellite Launch Center in Sichuan province. It is the only vessel to have landed on the dark side of the moon.

According to China’s state-run Xinhua news agency, ground control center instructed the probe to begin watering the plants after Chang’e-4 landed on the far side of the moon on Jan. 3. A tube directs natural light on the surface of the moon into the canister to allow the plants to grow. Yeast, arabidopsis – a small, flowering plant of the cabbage family – rape and potato seeds are also on board, along with fruit fly larvae, said Liu Hanlong, the scientist leading the experiment. It is hoped the organisms could eventually form the basis of a simple mini biosphere.

Previous trips to the moon have tended to leave behind more mundane items; moon buggies, unmanned vehicles, bags of urine and even golf balls all scatter surface.

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Source:: Time – Science


Environmentalists Say Tiny Plastic ‘Nurdles’ Threaten Earth’s Oceans

(Bloomberg) — Environmentalists have identified another threat to the planet. It’s called a nurdle.

Nurdles are tiny pellets of plastic resin no bigger than a pencil eraser that manufacturers transform into packaging, plastic straws, water bottles and other typical targets of environmental action.

But the nurdles themselves are also a problem. Billions of them are lost from production and supply chains every year, spilling or washing into waterways. A U.K. environmental consultancy estimated last year that preproduction plastic pellets are the second-largest source of micro-plastic pollution in water, after micro-fragments from vehicle tires.

Now, shareholder advocacy group As You Sow has filed resolutions with Chevron Corp., DowDupont Inc., Exxon Mobil Corp. and Phillips 66 asking them to disclose how many nurdles escape their production process each year, and how effectively they’re addressing the issue.

As justification, the group cites estimates of high financial and environmental costs associated with plastic pollution, and recent international efforts to address it. These include a United Nations conference in Nairobi and a U.S. law banning micro-plastics used in cosmetics.

“We’ve had information over the last couple of years from the plastics industry, that they’re taking this all seriously,” said Conrad MacKerron, senior vice president of As You Sow. The companies say they have set goals to recycle plastics, he said. “This is really more of a bellwether moment, as to whether they’re serious … if they’re willing to come out, warts and all, and say ‘here’s the situation. Here are the spills that are out there. Here’s what we’re doing about them.’”

The companies already participate in Operation Clean Sweep, a voluntary industry-backed effort to keep plastics out of the ocean. As part of an initiative called OCS Blue, members are asked to share data confidentially with the trade group about the volume of resin pellets shipped or received, spilled, recovered and recycled, along with any efforts to eliminate leakage.

Jacob Barron, a spokesman for the Plastic Industry Association (PIA), an industry lobby, said “the provision about confidentiality is included to eliminate competitive concerns that might prevent a company from disclosing this information.” The American Chemistry Council, another lobbying group, co-sponsors OCS along with the PIA. In May, it announced long-term industry-wide goals to recover and recycle plastic packaging, and for all U.S. manufacturers to join OCS Blue by 2020.

There’s limited information on the extent of this kind of plastic pollution by U.S. companies, and global researchers have struggled to make an …read more

Source:: Time – Science