DiscoverSeptember 2017的目錄

It was February 1979, a late winter day in Montana, and school was out. It wasn’t a snow day. This was planned — thoroughly predicted — because the center line of a total eclipse would be mere miles from town. That morning, we walked across the dirt road to hike up our neighbor’s giant hill. We lived at the end of a road, down in a gulch, surrounded by hundreds of acres of wooded Forest Service land. To see anything, we needed to get up above the trees. I’d made a box with a pinhole in it in my third-grade classroom. I held it as we scrabbled up the hill and then waited for the moon to slide across the sun. I still can feel that sense of otherworldliness in…

IN THE SUMMER OF 2010, Oxford University physicist Justin Wark flew to Northern California to study the interiors of stars. The instrument he sought there was not a telescope, but rather a new kind of laser, more than 3,500 feet long and capable of emitting X-rays a billion times brighter than anything ever generated on Earth. It was worth the airfare. In the 60 hours he spent bombarding metal foils with X-rays — creating analogs to stellar plasma, or ionized gas — Wark pulled more data than he had from any single experiment in a quarter century. It was remarkable that the machine worked at all; nobody had ever made this kind of laser at any scale. Everything about the enormous Linac Coherent Light Source (LCLS) was a gamble, says…

LAVA MELTS ICE, RIGHT? It seems like a no-brainer, but it’s not quite that simple. Benjamin Edwards, a geologist at Dickinson College in Carlisle, Penn., has explored scores of volcanoes in British Columbia, Iceland, South America and Russia. His specialty is studying what happens when flowing lava meets ice and snow. Figuring out this interaction helps Edwards and his team understand a volcano’s climate history and better estimate flooding in nearby communities when snowcapped volcanoes erupt. In 2013, Edwards journeyed to Tolbachik, a complex of active volcanoes on eastern Russia’s remote Kamchatka Peninsula. When he and his team arrived at one of the volcanoes via helicopter, the peak was drooling lava across the rugged, snowy terrain. In his silver fire suit, Edwards stood next to a lava bank, took its…

On Aug. 21, the dark inner part of the moon’s shadow will sweep across the United States, creating a total solar eclipse for regions in 14 states. But, you may ask, the sun is so much larger than the moon, so how does this work? While our daytime star has a diameter about 400 times larger than that of the moon, it also lies roughly 400 times farther away. This means both disks appear to be the same size, so at certain times from certain locations, the moon can completely cover the sun. Be sure to protect your eyes during the partial phases. The simplest way is to buy a pair of solar viewing glasses. Wear them even when 99 percent of the sun is covered because the remaining part…

1 Is your daily slog through a non-equilibrium system of interacting particles — how physicists define vehicular traffic — getting you down? Us too, especially when it slows for no apparent reason. 2 According to a study in the New Journal of Physics, traffic jams develop spontaneously when vehicle density exceeds a critical level, beyond which minor fluctuations in the flow of individual vehicles destabilize the whole thing. 3 In fact, even construction or an accident isn’t directly responsible for congestion; the cause is the increase in vehicle density. 4 Traffic jams predate the automobile. William Phelps Eno, a pioneer of vehicular traffic control in the early 20th century, wrote about gridlock caused by horse-drawn carriages on the streets of his native New York City in the 1860s. 5 Also…

Paying Homage to Ohm I just finished reading your Heroes of Science (May 2017) issue that included the profiles of both well-known and unsung science heroes. I appreciated the variety of topics, epochs, genders and cultures presented. The references to volt, ohm and amp reminded me of a quip I once heard while I was teaching at the Naval Postgraduate School around the same time as Richard Hamming (of Hamming Code fame). When asked about his role in the science and engineering community, he responded: “I’ll know I’m really famous when they stop capitalizing my last name.” Jeff Goldfinger, San Diego Our Unsung Heroes As a retired science and math teacher, I especially appreciated the section Heroes of Science (May 2017). In the fall of 2008, I learned about the naturalist…

THERE, OFF IN THE DISTANCE: It’s a mountain … it’s a hill … it’s a pingo! These mounds may appear mundane, but beneath their earthy exterior is a core of ice. Sometimes called hydrolaccoliths, pingos typically form in arctic regions, like Siberia and northern Canada. In such frigid climates, groundwater collects and freezes, amassing ice beneath the surface that eventually forces the ground up. They can reach heights of over 170 feet, and if the core melts, they can leave behind giant sinkholes — a popular explanation among experts for the mysterious Siberian sinkholes that made headlines back in 2014.…

Building Blocks Bacteria That Shape Blood Vessels Researchers have discovered a surprising link between gut-dwelling bacteria and the brain’s blood vessels. Cerebral cavernous malformations (CCMs) are capillaries that are enlarged or deformed and thinwalled, making them vulnerable to leaks — which can lead to stroke or seizure. To study these deformities, experts genetically engineered mice to form CCMs after an injection of a specialized drug. Some rodents went on to develop abdominal infections, thanks to the bacteria Bacteroides fragilis. Researchers realized when B. fragilis was present, the mice were more likely to have CCMs, and when the bacteria were eliminated, the CCM development stopped. The findings strengthen a growing body of evidence that the microbes of our intestines play an important and unexpected role in an array of maladies. How…

Totality’s eerie light bathes the ring of massive monoliths while robed figures chant and burn their sacrificial offerings. Around them, the gathered throngs raise their voices in joy and smile for the cameras of the CBS Evening News. It is 1979, and the scene is a bizarre roadside re-creation of Stonehenge overlooking the Columbia River in western Washington state. Neo-pagans and curious onlookers have amassed to witness the rare event unfolding overhead, and this being Washington (and the 1970s), it’s clear that not all the smiles and good vibrations are due solely to the solar eclipse. Back in the studio, Walter Cronkite tells us there will not be another total solar eclipse to touch the continental United States this century. Not until the far-off date of 2017 will totality once…

So before mission managers lose control, they’ve steered the spacecraft on a no-return course into Saturn’s atmosphere, where it’s scheduled to burn up Sept. 15 at about 3:45 a.m. PDT. The move is precautionary. A dead spacecraft carrying stowaway microbes could contaminate icy Enceladus, a moon Cassini showed us has a salty ocean and the potential for life. Instead, friction from the high-speed atmospheric entry will destroy Cassini. NASA launched Cassini from Cape Canaveral on Oct. 15, 1997, and it slid into Saturn’s orbit nearly seven years later. The robotic spacecraft proved so robust that NASA extended the mission twice. Its twin 1-megapixel cameras, built in the early ’90s, snapped thousands of pictures. Along the way, Cassini discovered seven moons and parachuted the Huygens probe down to Titan, the only…

After waiting months to use the Hubble Space Telescope, astronomer Ata Sarajedini was excited to have the instrument at his command. But his pictures were ruined when the guiding sensors failed to lock onto its target. Instead of pinpoints, the stars were rendered as streaks of light. After fixing the glitch, Hubble officials granted the University of Florida professor another session, but the flawed images stayed in Hubble’s database. Imaging expert Judy Schmidt saw artistry in the errors and assembled this abstract image for the Hubble Hidden Treasures contest. “I did this in jest,” Schmidt wrote in a description. “I thought it looked a little like a [Jackson] Pollock painting.”…

This August, the sky will dim until the daytime world becomes dark. The bright disk that usually lights everything, burns skin, feeds plants and tells animals when to sleep will become a blank circle, surrounded by the shifting haze of its atmosphere. This scene will pass over the United States, from Oregon to South Carolina, potentially capturing an audience even larger than the Super Bowl. And these people — including you, I hope — will likely react emotionally, not scientifically. It’s a human response that has played out for millennia, but one that humans have begun to study only recently. The moon is the same size as the sun in the sky and can, sometimes, pass in front of it in the ultimate cosmic photobomb. For many centuries, that light…