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    New data show how quickly light pollution is obscuring the night sky

    The night sky has been brightening faster than researchers realized, thanks to the use of artificial lights at night. A study of more than 50,000 observations of stars by citizen scientists reveals that the night sky grew about 10 percent brighter, on average, every year from 2011 to 2022.

    In other words, a baby born in a region where roughly 250 stars were visible every night would see only 100 stars on their 18th birthday, researchers report in the Jan. 20 Science.

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    The perils of light pollution go far beyond not being able to see as many stars. Too much brightness at night can harm people’s health, send migrating birds flying into buildings, disrupt food webs by drawing pollinating insects toward lights instead of plants and may even interrupt fireflies trying to have sex (SN: 8/2/17; SN: 8/12/15).

    “In a way, this is a call to action,” says astronomer Connie Walker of the National Optical-Infrared Astronomy Research Laboratory in Tucson. “People should consider that this does have an impact on our lives. It’s not just astronomy. It impacts our health. It impacts other animals who cannot speak for themselves.”

    Walker works with the Globe at Night campaign, which began in the mid-2000s as an outreach project to connect students in Arizona and Chile and now has thousands of participants worldwide. Contributors compare the stars they can see with maps of what stars would be visible at different levels of light pollution, and enter the results on an app.

    “I’d been quite skeptical of Globe at Night” as a tool for precision research, admits physicist Christopher Kyba of the GFZ German Research Centre for Geosciences in Potsdam. But the power is in the sheer numbers: Kyba and colleagues analyzed 51,351 individual data points collected from 2011 to 2022.

    “The individual data are not precise, but there’s a whole lot of them,” he says. “This Globe at Night project is not just a game; it’s really useful data. And the more people participate, the more powerful it gets.”

    Those data, combined with a global atlas of sky luminance published in 2016, allowed the team to conclude that the night sky’s brightness increased by an average 9.6 percent per year from 2011 to 2022 (SN: 6/10/16).

    Most of that increase was missed by satellites that collect brightness data across the globe. Those measurements saw just a 2 percent increase in brightness per year over the last decade.

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    There are several reasons for that, Kyba says. Since the early 2010s, many outdoor lights have switched from high-pressure sodium lightbulbs to LEDs. LEDs are more energy efficient, which has environmental benefits and cost savings.

    But LEDs also emit more short-wavelength blue light, which scatters off particles in the atmosphere more than sodium bulbs’ orange light, creating more sky glow. Existing satellites are not sensitive to blue wavelengths, so they underestimate the light pollution coming from LEDs. And satellites may miss light that shines toward the horizon, such as light emitted by a sign or from a window, rather than straight up or down.

    Satellites have missed some of the light pollution from LEDs, which emit in blue wavelengths. This image from the International Space Station shows LEDs in the center of Milan glowing brighter than the orange lights in the suburbs.Samantha Cristoforetti, NASA, ESA

    Astronomer and light pollution researcher John Barentine was not surprised that satellites underestimated the problem. But “I was still surprised by how much of an underestimate it was,” he says. “This paper is confirming that we’ve been undercounting light pollution in the world.”

    The good news is that no major technological breakthroughs are needed to help fix the problem. Scientists and policy makers just need to convince people to change how they use light at night — easier said than done.

    “People sometimes say light pollution is the easiest pollution to solve, because you just have to turn a switch and it goes away,” Kyba says. “That’s true. But it’s ignoring the social problem — that this overall problem of light pollution is made by billions of individual decisions.”

    Some simple solutions include dimming or turning off lights overnight, especially floodlighting or lights in empty parking lots.

    Kyba shared a story about a church in Slovenia that switched from four 400-watt floodlights to a single 58-watt LED, shining behind a cutout of the church to focus the light on its facade. The result was a 96 percent reduction in energy use and much less wasted light , Kyba reported in the International Journal of Sustainable Lighting in 2018. The church was still lit up, but the grass, trees and sky around it remained dark.

    “If it was possible to replicate that story over and over again throughout our society, it would suggest you could really drastically reduce the light in the sky, still have a lit environment and have better vision and consume a lot less energy,” he says. “This is kind of the dream.”

    Barentine, who leads a private dark-sky consulting firm, thinks widespread awareness of the problem — and subsequent action — could be imminent. For comparison, he points to a highly publicized oil slick fire on the Cuyahoga River, outside of Cleveland, in 1969 that fueled the environmental movement of the 1960s and ’70s, and prompted the U.S. Congress to pass the Clean Water Act.

    “I think we’re on the precipice, maybe, of having the river-on-fire moment for light pollution,” he says. More

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    Why We Meditate review: A convincing argument for regular meditation

    Is our evolving relationship with tech shifting our view of reality?This year saw the launch of ChatGPT, an AI that anyone can converse with, and the news that a quantum computer simulated a wormhole. Are our sensibilities about what is real changing, asks Chanda Prescod-Weinstein More

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    The James Webb telescope found ‘Green Pea’ galaxies in the early universe

    Galaxies that helped transform the early universe may have been small, round and green.

    Astronomers using the James Webb Space Telescope have spotted “Green Pea” galaxies dating to 13.1 billion years ago. These viridescent runts, spotted just 700 million years after the Big Bang, might have helped trigger one of the greatest makeovers in cosmic history, astronomers said at a January 9 news conference in Seattle at the American Astronomical Society’s annual meeting.

    Green Peas first showed up in 2009 in images from the Sloan Digital Sky Survey, an ambitious project to map much of the sky. Citizen science volunteers gave the objects their colorful name. Their greenish hue is because most of their light comes from glowing gas clouds, rather than directly from stars.

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    These galaxies are rare in the present-day universe. Astronomers think that the ones that do exist are analogs of galaxies that were more plentiful in the early universe.

    “They’re a bit like living fossils,” said astrophysicist James Rhoads of NASA’s Goddard Space Flight Center in Greenbelt, Md. “Coelacanths, if you will,” referencing a fish thought to be extinct until it showed up off the coast of South Africa in 1938 (SN: 12/2/11). 

    These galaxies leak much more ultraviolet light, which can rip electrons from atoms, than typical galaxies do. So Green Peas dating to the universe’s first billion years or so could be partly responsible for a dramatic and mysterious cosmic transition called reionization, when most of the hydrogen atoms in the early universe had their electrons torn away (SN: 1/7/20).

    Three ancient Green Peas turned up in JWST’s first image, released in July 2022 (SN: 7/21/22). The objects look red in JWST’s infrared vision, but the wavelengths of light they emit are like those of the previously discovered Green Peas. The findings were also published in the Jan. 1 Astrophysical Journal Letters.

    “This helps us explain how the universe reionized,” Rhoads said. “I think this is an important piece of the puzzle.” More

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    The best video games out in 2023

    Brain training apps claim to make us smarter, but there is no evidenceThere are plenty of apps that offer mental exercises claiming to make users smarter the more they play. Not only are they not much fun, but studies show they have no effect on performance, says Adrian Hon More

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    Don’t Miss: Reading up on Quantum Theory, As Simply As Possible

    New Scientist’s weekly round-up of the best books, films, TV series, games and more that you shouldn’t miss

    Humans

    11 January 2023

    Read
    Quantum Field Theory, As Simply As Possible is delivered with humour and erudition by Anthony Zee. What better way to get the little grey cells going than by unifying quantum mechanics and special relativity? On sale from 17 January.
    NASA/JPL-Caltech
    Watch
    Hearing the Light is a talk by Clara Brasseur about representing telescope data as sound, also called astronomical data sonification. Listen to real data from the Kepler Space Telescope (pictured above) in her online talk on 20 January at 7.30pm GMT.

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    Cold People struggle to … More

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    How to force your rhubarb for an earlier, sweeter crop

    Depriving rhubarb plants of light for several weeks forces them to grow fast and gives an earlier harvest, says Clare Wilson

    Humans

    11 January 2023

    By Clare Wilson
    GAP Photos/Clive Nichols
    I HAVE just finished one of the few winter jobs at my allotment: preparing my rhubarb patch, including setting up one of the plants to be forced. This means covering it with a large container to make the stalks grow more quickly in search of light.
    If you have the space, I highly recommend getting a few rhubarb plants as they are so easy to grow. I give mine little attention, but each spring they produce a huge crop when there isn’t much home-grown produce around. Technically, rhubarb stems are a vegetable as they are the plant’s leaf stalks, but … More

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    Remnants of Ancient Life review: Explore the palaeobiology revolution

    Dale Greenwalt’s book is a gripping look at palaeobiology, a field achieving incredible insights into ancient life on Earth

    Humans

    11 January 2023

    By Simon Ings
    The palaeontology collection at the Smithsonian’s National Museum of Natural Historychip clark/museum of natural history
    Remnants of Ancient Life
    Dale Greenwalt (Princeton University Press)
    WHAT is a fossil made of? Mineralised rocky fossils are what first spring to mind, but others, like the fossils of the Burgess Shale in Canada, are made of pure carbon and can be thought of as proto-coal. There are also tantalising Cretaceous insects preserved in amber.
    Whatever they are made of, fossils contain treasures. The first really good microscopic study of mineralised dinosaur bone was able to reveal its … More