Signs of Life

“If alien astronomers are out there searching for signs of life on Earth, they might just find it in the telltale pattern of light reflected by our plants, from redwood forests to desert cacti to grass-covered plains. That reflected fingerprint has been visible since vegetation first began carpeting our rocky terrestrial landscape about half a billion years ago. And as Earth aged and evolution marched onward, the reflected signal strengthened.

“Now, two astronomers are suggesting that plants could leave similar fingerprint-like patterns on distant exoplanets, and perhaps the first signs of life beyond our solar system could come from light reflected by forests covering an alien moon like Endor or cacti living in Tatooine’s deserts.

 
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“We’re trying to figure out—with all the planets we’re finding—what are the signatures that could indicate habitability?” says Cornell University’s Lisa Kaltenegger, who recently described Earth’s leafy signature in a study published in the journal Astrobiology.

“We really want to identify the handful, or two or three, that give us the best chance to pick up signs of life.”

“While this isn’t the first time scientists have suggested looking for life in a far-off planet’s light, Kaltenegger’s team adds a twist: Such reflections can also offer a good estimate for an alien planet’s evolutionary advancement, based on our knowledge of how things work on Earth.

“This idea that you could find vegetation on another planet has been around. But nobody ever used Earth’s own geological history as an archive,” Kaltenegger says. “We don’t have a second planet with habitability, but we do have our Earth through time, and it would be really smart to study it.”

“Several decades ago, the Galileo spacecraft, which was headed for Jupiter, swiveled to stare at Earth’s reflected light. It spied the signs of biology at work in the presence of atmospheric gases such as ozone and methane. More recently, astronomers have teased apart Earthshine, or the bit of Earth-light that sometimes dimly illuminates the darker part of a crescent moon’s face. They found life’s fingerprints there, too.

“Now, scientists searching for life beyond Earth are debating how biology might leave molecular marks in alien atmospheres, either by producing particular compounds or by shifting the mix of gases swaddling a planet.”

Text: “Want to Find Alien Life? Look at Older, Hotter Earths”, National Geographic.
Image: L’occhio di Shui (The Eye of Shui) by Shui Mao.

The Local Standard of Rest

“Whereas all the planets, asteroids and meteors that originate within the solar system more or less circle what is called the Ecliptic plane, that of our sun, since they were formed from the same disc of gas and dust that rotated around itself, Oumuamua entered the solar system north of the plane, in an extreme hyperbolic orbit and at a speed of 26.3 kilometers per second faster relative to the motion of the sun.

“A reconstruction of its trajectory shows that Oumuamua traversed the ecliptic plane on September 6, 2017, when the sun’s gravity accelerated the object to a velocity of 87.8 kilometers per second. On September 9, the object passed closer to the sun than the orbit of Mercury. And on October 14, five days before it was discovered in Hawaii, the object passed 24.18 million kilometers away from Earth, or 62 times the distance from here to the moon.

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“I wrote above that Oumuamua originated at Vega, but that’s not completely accurate: The universe is a vast place, and even at Oumuamua’s velocity – a velocity that no human spaceship has achieved – a voyage from Vega to the solar system would take 600,000 years. But in the meantime, Vega is orbiting the center of the Milky Way, like the sun and all the other stars, and it wasn’t in that region of the heavens 600,000 years ago.

“If you average the velocities of all the stars in the region, you get a system that’s called the ‘local standard of rest.’ Oumuamua was at rest relative to that system. It didn’t come to us. It waited in place, like a buoy on the surface of the ocean, until the ‘ship’ of the solar system ran into it. To make things clear, only one of 500 stars in the system is as much at rest as Oumuamua. The probability of that is very low. After all, if it were a stone that was simply hurled from a different solar system, we would expect it to have the velocity of its star system, not the average velocity of all the thousands of stars in the vicinity.”

Text: “If True, This Could Be One of the Greatest Discoveries in Human History”, Haaretz.

Image: Augsburger Wunderzeichenbuch, Comet mit einem grosen Schwantz, 1401

Life Support

“We knew that something was amiss in the first couple days,” said Brad Lister. “We were driving into the forest and at the same time both Andres and I said: ‘Where are all the birds?’ There was nothing.”

His return to the Luquillo rainforest in Puerto Rico after 35 years was to reveal an appalling discovery. The insect population that once provided plentiful food for birds throughout the mountainous national park had collapsed. On the ground, 98% had gone. Up in the leafy canopy, 80% had vanished. The most likely culprit by far is global warming.

“It was just astonishing,” Lister said. “Before, both the sticky ground plates and canopy plates would be covered with insects. You’d be there for hours picking them off the plates at night. But now the plates would come down after 12 hours in the tropical forest with a couple of lonely insects trapped or none at all.”

“It was a true collapse of the insect populations in that rainforest,” he said. “We began to realise this is terrible – a very, very disturbing result.”

“It was not insects that drew Lister to the Luquillo rainforest for the first time in the mid-1970s. “I was interested in competition among the anoles lizards,” he said. “They’re the most diverse group of vertebrates in the world and even by that time had become a paradigm for ecology and evolutionary studies.”

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“The forest immediately captivated Lister, a lecturer at Rensselaer Polytechnic University in the US. “It was and still is the most beautiful forest I have ever been in. It’s almost enchanted. There’s the lush verdant forest and cascading waterfalls, and along the roadsides there are carpets of multicoloured flowers. It’s a phantasmagoric landscape.”

“It was important to measure insect numbers, as these are the lizards’ main food, but at the time he thought nothing more of it. Returning to the national park decades later, however, the difference was startling.

“One of the things I noticed in the forest was a lack of butterflies,” he said. “They used to be all along the roadside, especially after the rain stopped, hundreds upon hundreds of them. But we couldn’t see one butterfly.”

“Since Lister’s first visits to Luquillo, other scientists had predicted that tropical insects, having evolved in a very stable climate, would be much more sensitive to climate warming. “If you go a little bit past the thermal optimum for tropical insects, their fitness just plummets,” he said.

“As the data came in, the predictions were confirmed in startling fashion. “The number of hot spells, temperatures above 29C, have increased tremendously,” he said. “It went from zero in the 1970s up to something like 44% of the days.” Factors important elsewhere in the world, such as destruction of habitat and pesticide use, could not explain the plummeting insect populations in Luquillo, which has long been a protected area.”

Text: Insect collapse: ‘We are destroying our life support systems’, The Guardian.

Pollution Season

“When Deepikah Bhardwaj was a child in New Delhi, she would look forward to the arrival of the Indian winter. The mornings would become chilly and crisp, while evenings were pleasantly cool. But in recent years, that sense of anticipation turned to dread.

“With falling temperatures came a thick smog, leaving her short of breath and afraid to go outside. After her son was born in 2016, she decided it was time to act. These days, when she thinks of Delhi, her main emotion is relief at having escaped.

“I feel bad that I cannot go back to my home city, ever,” said Bhardwaj, 33, sitting in her light-filled apartment in the state of Goa on India’s western coast, more than 1,000 miles from Delhi. “It’s a feeling of permanent loss, like a friend who didn’t say goodbye.”

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“Bhardwaj is part of a small but growing contingent of what might be called pollution refugees: people who have decided that the only way to cope with Delhi’s staggering pollution is to run from it. Some, like Bhardwaj, have left the Indian capital for Goa, while others have decamped for Bangalore, Mumbai or even Canada.

“The phenomenon appears limited to an elite few — a trickle in comparison to the influx of people who arrive in Delhi every day in search of economic opportunity. But the departures pose a pointed rebuke to the city’s expanding ambitions: How great is a city if its air causes some of the people who live there to flee?

“According to the World Health Organization, Delhi has the most polluted air of any major metropolis in the world. The causes are multiple — vehicle exhaust, construction dust, industrial emissions, crop burning in nearby states — and exacerbated by geographic factors.

“The “pollution season” in greater Delhi, home to 29 million people, begins in October and persists for months. November and December bring the worst readings of the year: Last week, the level of the particulate matter considered most harmful to human health spiked for several hours to more than 40 times the level recommended by the WHO before receding. Such particles can lodge deep within the lungs and have been linked to high blood pressure, heart disease, respiratory infections and even cancer.”

Text: Joanna Slater, India’s pollution refugees: People are fleeing Delhi because of the toxic air, Washington Post.

Image: Claude Monet, Waterloo Bridge the Sun in a Fog, 1903. “Faced with a polluted industrial landscape […] artists abandoned realism and sought out beauty in the modern urban environment. Inspired by contemporary art theory and poetry, their works are rich in environmental, political and metaphysical overtones” – Turner, Whistler, Monet – Aesthetics, Pollution and the City, 2005.

An Eerie Dystopia

“To walk through certain parts of London today is to enter an eerie dystopia of late capitalism run amok. All over town, from Battersea to Stratford, vast welters of towers are in the throes of construction, invariably encircled by billboards depicting attractive white people at rest and play. But longtime Londoners know from experience that these towers are not really homes to be lived in but bricks-and-mortar commodities, investment opportunities that until recently were seen as safer than any government bond. If you ever find yourself walking through developments that have been recently finished and sold, you’ll discover street-level plazas devoid of people or even much evidence that many people are ever here…

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“In her 2017 book Big Capital, Anna Minton described this scramble for prime London real estate as the catalyst of a “domino effect,” whose effects ripple outwards across the capital and beyond.

“The super-prime market displaces established communities to new areas, driving up property and rental prices elsewhere,” she writes. “And as current policies are geared to attracting foreign investment and building luxurious apartments rather than affordable homes, there is nothing to act as a counterweight.”

“The sense of apartness precipitated by these developments is in large part architectural. London used to be a low-slung city, but many of these luxury towers are vertiginous and imposing, dwarfing the besieged remnants of what came before. But arguably more significant than this aesthetic discordance is the social upheaval it augurs. As more and more towers have gone up, so too have socio-demographic lines that once felt blurred become abrupt and partite, as the runaway cost of housing manoeuvres people into economic enclaves, and poverty is pushed outwards into peripheries and ghettoes of disadvantage. Traditional places of commonality, where shoulders rubbed, have been replaced by pockets of consumption. High-streets that once displayed a multifarious range of shopfronts and establishments have evolved to reflect more stratified times: the poorer areas with their betting shops and pawnsters, the wealthier ones lined with estate agents, restaurants, and prim cafes. Our civic spaces and landmarks have been commodified as cash-strapped councils look to make up budget shortfalls by monetizing their assets or repurposing public libraries into private gyms. Boundaries, both physical and social, have started to rise across the city…”

Text: Henry Wismayer, How London Became a Playground for the Rich, Medium.

Pic: London’s proposed Tulip Tower