Why People In Ancient Times Didn’t Get the Plague

By Sonja Eliason and Bridget Alex, The Conversation | November 12, 2019 2:14 pm
What happened to make plague able to cause devastating epidemics, as in this depiction from 1349? (Credit: Pierart dou Tielt/Wikimedia)

One of civilization’s most prolific killers shadowed humans for thousands of years without their knowledge.

The bacteria Yersinia pestis, which causes the plague, is thought to be responsible for up to 200 million deaths across human history — more than twice the casualties of World War II.

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CATEGORIZED UNDER: Health & Medicine

What It Takes to be a Space Pilot

By Mara Johnson-Groh | November 8, 2019 12:52 pm
Virgin Galactic’s SpaceShipTwo. The craft is flown by human pilots to space. (Credit: Steve Mann/Shutterstock)

Taking control of a 3,000-pound rocket motor launching into an inhospitable environment at speeds exceeding 2,000 mph sounds terrifying to some. But others will spend their whole careers in pursuit of those ephemeral, weightless moments.

With the expansion of commercial space exploration, more pilots will be needed to guide spacecraft beyond the bounds of Earth. These pilots come from a wide variety of backgrounds, but they all have one thing in common: lots of flying experience.  Here’s a look at what it takes to become a space pilot.

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CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: spacecraft, spaceflight

Voracious and Invasive Lionfish Are Tearing Through Florida’s Coral Reefs

By bioGraphic | November 5, 2019 3:26 pm
A young lionfish photographed during a dive in Palm Beach, Florida. (Credit: Steven Kovacs)

Descending into pitch-black open ocean under the cover of inky skies can unnerve even experienced divers, but for underwater photographer Steven Kovacs, it’s a surprisingly addictive activity. “It’s like a treasure hunt. You never know what amazing creature will drift by or come up from the depths.”

While Kovacs has documented the strange and beautiful larval forms of many species during such dives, this opalescent lionfish fry (Pterois volitans) was a particularly arresting sight. Turning in slow circles at a depth of around 500 feet, the larval fish was — for the moment — a peaceful ocean drifter. In a matter of weeks, however, it would become a voracious predator primed to decimate nearby reef ecosystems.

If Atlantic coral reefs had a Most Wanted list, the invasive red lionfish would certainly be at the top. Native to the Indian and Pacific Oceans, the species first arrived in the United States via the aquarium trade. Since the first few individuals appeared in Florida’s reefs in 1984, lionfish have spread and proliferated with astonishing speed.

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: ecosystems, ocean

How to Stay Fit As You Age — Into Your 60s and Beyond

By Julie Broderick, The Conversation | November 5, 2019 1:05 pm
(Credit: Alex Brylov/Shutterstock)

Ageing is inevitable and is influenced by many things – but keeping active can slow aging and increase life expectancy. Evidence shows that ageing alone is not a cause of major problems until you are in your mid-90s. And strength, power and muscle mass can be increased, even at this advanced age.

So here are my top exercise tips for people in their 60s and older, at different levels of fitness.

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CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: personal health

Monte Verde: Our Earliest Evidence of Humans Living in South America

By Bridget Alex | November 1, 2019 3:22 pm
Monte Verde
The site of Monte Verde in Chile today. Credit: (Geología Valdivia/Wikimedia Commons)

As the Ice Age began to wane, people from northeastern Asia spread to the Americas, some of the last uninhabited continents on Earth. The pioneers traveled south of mile-high ice sheets covering Canada and found vast lands, abounding with mammoth, giant sloth and other now-extinct megafauna.

This much has been known for decades. But when it comes to the details, debates have raged over precisely when and how humans populated the New World. Today, the story is beginning to take shape, thanks to well-dated archaeological sites, DNA analysis and geological work to understand when ice and sea levels permitted entry to the Americas. It’s clear that people occupied the continents by about 15,000 years ago, probably taking a route along the Pacific coast.

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: archaeology

Why Desalinating Water is Hard — and Why We Might Need To Anyway

By Jillian Mock | November 1, 2019 1:46 pm
Hamburg Desalination Plant
A desalination plant in Hamburg, Germany. (Credit: Andrea Izzotti/Shutterstock)

In places like San Diego and Dubai, where freshwater is scarce, humans turn to machines that pull the salt out of seawater, transforming it into clean drinking water.

This process, called desalination, has been turning sea and brackish groundwater into potable water since the mid-20th century. The technology could become increasingly important in the near future, as the rising temperatures and erratic rain patterns of climate change threaten freshwater supplies. Cities with growing populations and arid climates face the possibility of running out of water, as Cape Town almost did in early 2018. But desalination is also costly and energy intensive. Many researchers are working to improve the technology so it can reach more people — and address climate change without contributing to it.

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CATEGORIZED UNDER: Environment, Top Posts
MORE ABOUT: sustainability

Creepy Music and Soviet Spycraft: The Amazing Life of Leon Theremin

By Nathaniel Scharping | October 31, 2019 3:57 pm
Leon Theremin, also known as Lev Termen, demonstrates his musical instrument. (Credit: Wikimedia Commons)

Imagine a UFO descending from the heavens, its round disk pale against the night sky. What sound does it make? You’re likely imagining a keening whine in your head, like the howling of a haunted wind or the moans of a high-pitched ghost.

That’s the sound of the theremin, a musical instrument invented nearly a century ago. It was one of the first electronic musical instruments, and the first to be mass-produced. The theremin’s ethereal tones made it ubiquitous in science fiction film scores during the middle of the 20th century.

But the curious instrument was actually invented decades earlier, in 1920, by a Russian scientist named Lev Sergeyevich Termen. As a young man working at the Physical Technical Institute in Petrograd, he noticed that something odd happened when he hooked up audio circuits to an electrical device called an oscillator in a certain configuration. The oscillator produced an audible tone when he held his hands near it, and he could shift the tone just by waving his hands back and forth.

A classically trained cellist, Termen was immediately intrigued. Where other engineers may have seen a quirk of capacitators and circuits, he saw the opportunity to summon symphonies from the invisible.

Termen showed the device to his superiors and delivered the first concert with his device soon after. He followed with a private demonstration for Lenin in 1922, who was apparently intrigued by the strange device. The theremin — or etherphone, as it was originally called — had already become Termen’s calling card.

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CATEGORIZED UNDER: Technology, Top Posts

DC-X: The NASA Rocket That Inspired SpaceX and Blue Origin

By Hailey Rose McLaughlin | October 29, 2019 4:13 pm
DC-X rocket test flight
The first flight of the second version of the Delta Clipper, the DC-XA, at White Sands Missile Range in New Mexico. (Credit: NASA)

The rocket looked like it was out of a science fiction movie. A gleaming white pyramid resting on four spindly legs, the experimental craft was NASA’s ticket into a new era of space exploration.

With a series of built-in rockets on its underside, the ship could rise from the ground and touch back down again vertically — the first of its kind.

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CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: spaceflight

The Best of Voyager: The Longest-Running Space Mission in History

By Michael E. Bakich | October 29, 2019 2:18 pm
voyager test platform
The Voyager proof test model in the space simulator chamber at NASA’s Jet Propulsion Laboratory on December 3, 1976. (Credit: NASA/JPL-Caltech)

When NASA launched Voyager 1 and Voyager 2 in the summer of 1977, its engineers were sending the spacecraft on specific missions. Originally, the space agency tasked the Voyagers with conducting close-up studies of Jupiter and Saturn. They would compile data on magnetic fields, the Sun’s influence, Saturn’s rings, a few large moons, and send back lots of great images. To accomplish all this, engineers built into them a generous (for the 1970s) five-year lifetime.

At Jupiter, and then Saturn, the mission achieved far more than its original objectives. Then came the big news: By carefully tweaking Voyager 2’s flight path, flybys of Uranus and Neptune were possible.

The two-planet addition became the Grand Tour. The projected lifetimes stretched to 12 years for the Neptune encounter August 24, 1989. And that date would, in turn, become early history. As of 2018, both Voyagers have finished their fourth decade of operation — and they show no signs of stopping.

Voyager Grand Tour
(Credit: Roen Kelly)

One Surprise After Another

The Voyager spacecraft made enough discoveries to fill this magazine — and we did just that for our October 2017 issue — but most scientists would view the following as the top 10.

As Voyager 1 flew by the jovian moon Io, it captured this image of an active plume (left edge, bluish white) coming from Loki, a volcano then on Io’s limb, from 340,000 miles (490,000 km) away. The dark heart-shaped feature near the bottom shows fallout deposits from the active plume Pele. (Credit: NASA/JPL/USGS)

1) Volcanoes on Jupiter’s moon Io. This was the biggie. While processing a Voyager 1 image, navigation engineer Linda Morabito discovered a feature along Io’s edge. What she initially thought was a moon turned out to be a plume from an active volcano. Planetary geologists subsequently learned Io’s interior is in turmoil: Jupiter’s gravity stretches it differently depending on how far the moon is from the planet. Such an interaction creates intense heating due to friction. The result is that Io has 100 times as much volcanic activity as Earth.

2) Jupiter’s turbulent atmosphere. After watching the giant planet’s cloud bands and Great Red Spot from afar for three centuries, scientists got their first up-close look with Voyager 1. They saw dozens of interacting hurricanes, some as large as planets. And the Red Spot itself displays layers of complex activity. It lies 5 miles (8 kilometers) above the surrounding clouds, and time-lapse movies confirmed its counterclockwise rotation.

Voyager Jupiter
The Great Red Spot is a spinning anti-cyclone in Jupiter’s southern hemisphere. At the time Voyager 1 snapped this close-up of swirling clouds, the Great Red Spot was three and a half times the size of Earth. (Credit: NASA/Goddard Space Flight Center)

3) An ocean within Europa? As the two spacecraft flew by the fourth-largest jovian moon, its icy crust showed a dizzying series of intersecting cracks. Calculations indicated the possibility of a liquid ocean deep beneath the ice. Such a feature likely exists because of the tidal interaction between the moon and Jupiter. But Europa’s orbit is closer to circular than Io’s, so the internal heating isn’t enough to create volcanoes — just enough to melt vast quantities of ice.

4) The Io torus. Voyager 1 found a thick ring of ionized sulfur and oxygen shed by Io that inflates Jupiter’s giant magnetic field. The material originates within the moon’s volcanoes, some of which are so powerful that they erupt it directly into space.

Voyager 2 revealed Europa’s surface to be devoid of mountains or craters as the spacecraft flew by the jovian satellite July 9, 1979. The main feature it did show was a network of crisscrossing streaks. The lines are where warmer ice broke through the colder surface when tidal forces from Jupiter and its other large moons cracked the outer layer of the moon. (Credit: NASA/JPL/Ted Stryk)

5) Saturn’s ring structure. Before 1980, astronomers recognized fewer than six rings around Saturn. But Voyagers’ cameras showed that each ring had numerous subdivisions. In addition, Voyager 1 discovered that the enigmatic F ring has two small “shepherding” satellites, Pandora and Prometheus, whose gravity keeps the ring in place.

6) Titan’s atmosphere. Voyager 1 showed that Titan has a nitrogen atmosphere with a surface pressure 45 percent greater than on Earth. Voyager data hinted at the possibility (later confirmed) that this satellite experiences clouds of methane and other hydrocarbons, and that rain falling from those clouds creates lakes of liquid methane on the surface.

7) The Great Dark Spot. As Voyager 2 approached Neptune, scientists identified a gigantic dark feature. It was dubbed the Great Dark Spot, and researchers were at a loss to explain how such a storm could form given the small amount of energy Neptune receives from the Sun. Further study showed the Great Dark Spot, and similar features observed since Voyager 2 passed by, are cyclones that exist as holes in the planet’s upper atmosphere.

8) Neptune’s supersonic winds. The discovery of the fastest winds in the solar system in the atmosphere of the most distant planet was a stunner. Voyager 2 measured wind speeds of 1,100 mph (1,600 km/h) above Neptune. Because the planet radiates 2.6 times as much energy as it receives from the Sun, researchers think the decay of radioactive elements deep within Neptune powers the currents.

Voyager Triton
Voyager 2 took this global color mosaic of Triton, Neptune’s largest moon. It is one of only three objects in the solar system with an atmosphere of mainly nitrogen. (The others are Earth and Titan.) But this moon is so cold (–391 degrees Fahrenheit) that most of the nitrogen has condensed on the surface as frost. (Credit: NASA/JPL/USGS)

9) Geysers on Triton. In addition to observing clouds and hazes in the thin atmosphere of Neptune’s largest satellite, Voyager 2 found evidence of cryovolcanoes — otherwise known as ice volcanoes. These active geysers within the moon’s southern polar cap spew dust-laden nitrogen up to 5 miles (8 km) above the surface, which lies in perpetual cold at a temperature of 37 kelvins (–393 degrees Fahrenheit).

10) The edge of the solar system. The Voyager spacecraft didn’t stop working after their planetary encounters. In 2014, Voyager 1 passed an important boundary within our solar system called the heliopause. This is where the strength of the solar wind isn’t powerful enough to overcome the stellar winds of nearby stars. Voyager 1 crossed another border, the termination shock, where the solar wind abruptly slows to subsonic speed, back in 2004. Voyager 2 followed in 2007. As each spacecraft crossed the heliopause, their Voyager Interstellar Mission commenced.

A New Horizon

As of February 8, 2018, Voyagers 1 and 2 are 13.16 billion miles (21.18 billion km) and 10.91 billion miles (17.56 billion km) from Earth, respectively. And the craft are still making news. In 2011, Voyager 1 crossed into a zone astronomers call the stagnation region. There, at the boundary of interstellar space, the solar wind is less intense, but the magnetic field measures twice as strong.

Voyager 1 is leaving the solar system at about 320 million miles (520 million km) per year. Meanwhile, Voyager 2 is exiting at about 290 million miles (470 million km) per year.

Both spacecraft continue to study ultraviolet sources among the stars and the boundary between the Sun’s influence and interstellar space. Communications will be maintained until the Voyagers’ power sources no longer can run critical subsystems.

A Legacy of Discovery

The grand tour of the solar system (and beyond) continues. The primary explorers are two workmanlike spacecraft that achieved the goals scientists set before them, far surpassed their planned life spans, and adapted to new expectations by evolving technologically. Indeed, more than 40 years after their launches, Voyager 1 and Voyager 2 continue to go where no one has gone before.

CATEGORIZED UNDER: Space & Physics, Technology
MORE ABOUT: spacecraft

After 40 Years, These Voyager Instruments Are Still Talking to NASA

By John Wenz | October 29, 2019 1:16 pm
Voyager Profile
This artist’s concept shows Voyager 1 entering the interstellar medium. (Credit: NASA/JPL-Caltech)

1. High-Gain Antenna
SHUTDOWN DATE: Still active
PURPOSE: Communications
KEY FINDING: This is the craft’s main contact point with Earth. It once sent back the robust data from the craft; today, it sends out basic information from the low-power instruments still online.

2. Magnetometers and Low-Field Magnetometer

SHUTDOWN DATE: Still active
PURPOSE: Measure the magnetic fields of the Sun and the outer planets.
KEY FINDING: In 2015, the craft discovered that even past the heliopause, solar winds can redirect the magnetic field of charged particles they encounter.

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CATEGORIZED UNDER: Space & Physics, Top Posts

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