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Iceland volcano erupts, after weeks of earthquakes

For weeks, volcanologists had been predicting an eruption of a volcano in southwestern Iceland, on the Reykjanes Peninsula, in the most populated part of the country. There’d been earthquakes near the town of Grindavik, about 2.4 miles (4 km) away. And there’d already been evacuations. Then, yesterday, boom! The volcano suddenly blew, blasting lava fountains high into the sky. Ultimately, volcanologists said, the eruption was more powerful than they’d expected, lighting up the sky miles away in the center of Iceland’s capital, Reykjavik, only about 30 miles (50 km) away.

AP reported:

The town near Iceland’s main airport was evacuated in November after strong seismic activity damaged homes and raised fears of an imminent eruption.

Iceland, which sits above a volcanic hotspot in the North Atlantic, averages an eruption every four to five years. The most disruptive in recent times was the 2010 eruption of the Eyjafjallajokull volcano, which spewed huge clouds of ash into the atmosphere and led to widespread airspace closures over Europe.

WATCH: Volcano erupts in Iceland, lava shooting into the air from fissure extending 2.5 miles (4 km) pic.twitter.com/M93QePO4wK

— BNO News (@BNONews) December 19, 2023

Will it close airports in Europe?

But this eruption is not expected to produce as much ash, AP said. In fact, according to AP:

Iceland’s Foreign Minister Bjarne Benediktsson said on X, formerly Twitter, that there were no disruptions of flights to and from Iceland and international flight corridors remain open.

Big fissure, getting bigger

Meanwhile, the New York Times reported that the volcano’s fissure is:

… some 2.5 miles [4 km] long and growing quickly … [It’s] not far from the Svartsengi Power Plant and the town of Grindavík, which was evacuated last month because of heightened seismic activity, leading to concerns than an eruption was likely.

The Times said that the direction of the lava flow is still “unpredictable.”

More reports from volcano-watchers

The moment the eruption in Iceland started. This just blows my mind!!! pic.twitter.com/xOegj91xMQ

— Volcaholic ? (@volcaholic1) December 18, 2023

Reykjanes volcano in Iceland is erupting! 154 small earthquakes in under 2 hours. 3.5km (just over 2 miles) long fissure eruption. Things can change rapidly on the ground, but this pic by the Iceland Coast Guard is stunning. pic.twitter.com/UKy93Qfyx1

— Jess Phoenix, Lava Connoisseur ? (@jessphoenix2018) December 19, 2023

Bottom line: After weeks of earthquakes, an Iceland volcano – on the Reykjanes Peninsula – began erupting powerfully on December 18, 2023. It was a bigger eruption than volcanologists had predicted!

Via AP

Via the New York Times

The post Iceland volcano erupts! See a livestream here first appeared on EarthSky.

Scientists often field check their findings, heading outside to see if computer models match with what is happening in the real world. But doing so is challenging when the field is 2 1/2 miles (4,000 m) up. Enter a new field assistant: the great frigatebird.

Great frigatebirds live in tropical regions and routinely fly to 1.25 miles (2,000 meters) in altitude. Occasionally they even reach heights of 2.5 miles (4,000 meters). A new study shows that great frigatebirds equipped with tiny sensors can give detailed information about the planetary boundary layer. The planetary boundary layer is the dynamic atmospheric layer closest to Earth. It’s where we experience weather, air quality and climate impacts. Scientists presented the new research at the AGU Annual Meeting on Wednesday, December 13, 2023, in San Francisco and online.

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Investigating the planetary boundary layer

The planetary boundary layer connects the atmosphere with the surface ocean, land and ice. It rises and falls throughout the day. Ian Brosnan, a marine scientist at NASA’s Ames Research Center who led the work, said:

Many weather and climate processes are related to that fluctuation. So understanding planetary boundary layer dynamics is fundamental to answering a lot of questions about the Earth system.

Current techniques typically rely on ground-based measurements or remote sensing, but for far-flung regions over the oceans, Brosnan said:

… getting in situ samples of any sort at scale is a challenge.

Enter the great frigatebirds

Brosnan’s co-author, NASA ecologist Morgan Gilmour, previously used sensor-laden great frigatebirds to assess whether the boundaries of a marine protected area around Palmyra Atoll in the Pacific Ocean protected the animals within it. Brosnan suspected the frigatebirds’ flights were related to the planetary boundary layer. If so, Gilmore’s project had also collected critical planetary boundary layer samples. Brosnan said:

I instantly thought the birds could be traveling to the top of the planetary boundary layer, turning around, and coming back down. And they’re probably covering a pretty broad area, too.

To check if the birds’ flight patterns matched planetary boundary layer altitudes, they compared planetary boundary layer measurements from 2006-2019 analysis to frigatebirds’ flights. They found that the long-term average planetary boundary layer heights in that area very closely matched the bird’s altitude data. Brosnan’s hunch was right.

The tagged frigatebirds had sampled temperature profiles in the planetary boundary layer and had no trouble collecting data during cloudy weather or at night, unlike traditional sampling approaches. Brosnan said:

These novel approaches to using animal tracking data can help NASA measure the planetary boundary layer and improve climate predictions and weather and air quality forecasts.

Internet of Animals

Brosnan mentioned that after hearing from interagency scientists about how important global, satellite-based animal tracking data was for their research projects, NASA created the Internet of Animals project. This allows scientists to integrate data from remote sensing measurements with data from sensors on animals, now including the great frigatebird planetary boundary layer data.

Brosnan said their work is a good example of how interagency and interdisciplinary collaborations can help tackle larger science questions:

One of the things we’re trying to do is bridge between these two communities – animal tracking and atmospheric science – and see if we can enrich the work that we both do.

Bottom line: A new study from NASA’s ‘Internet of Animals’ project shows that high-flying great frigatebirds can provide detailed sampling of the atmospheric layer located closest to Earth, where weather and climate directly impact us.

Source: A31M-2550 Can tagged great frigatebirds (Fregata minor) be used to track the dynamics of the planetary boundary layer height?

Via AGU

Read more: Animals on the brain? There’s a scientific reason

The post Birds with backpacks to help study Earth’s atmosphere first appeared on EarthSky.

Rain that doesn’t reach the ground

Have you seen clouds that are pouring rain … but the rain never reaches the ground? Meteorologists call this rain by the name virga. You see virga in places where the air is dry, and often warm. The rain evaporates as it falls, before hitting Earth. So you might see virga in a desert, or at high altitudes, for example, in the western U.S. and Canadian prairies, the Middle East, Australia and North Africa. Virga isn’t rare. But it’s delicate and very beautiful. Maybe you’ve seen it lots of times, but never knew it had a name?

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Virga on radar

Sometimes, when you’re looking at your weather app, you might see what looks like rain or snow on the radar, but nothing is falling outside. Instead, look up at the clouds and see if you can spot virga. The radar is picking up precipitation in the air which is just not reaching the ground. As weather.gov says:

The radar isn’t lying, rather, the the rain or snow is not hitting the ground. If you have a dry air mass in place in the low levels, sometimes rain cannot completely penetrate that dry layer before it evaporates.

Do you want to learn to identify virga when you see it? Check out the photos on this page from our global EarthSky community. Once you acquaint yourself with the variations of virga, you’ll be able to spot it in your own sky. If you capture a photo of virga, submit it to us!

Photos of virga from EarthSky’s community

More photos

Bottom line: Learn what virga is and how it forms, and see great photos to help you learn how to identify it yourself!

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The post Virga is rain that doesn’t reach the ground first appeared on EarthSky.

An expedition to see emperor penguins

EarthSky friend Eliot Herman took a trip to the Antarctic in late November. After more than 30 hours of flights, he and his wife reached Antarctica, where they got to observe a resident colony of emperor penguins. He shared his fantastic photos with us, and reported from the southern reaches of the world:

We flew to the interior and landed on an ice runway, then to a camp and finally ski-plane to the emperor penguin colony at Atka Bay. With reports of the penguins having reproductive problems, I was concerned about what I would see. The colony we saw had a large population of healthy chubby chicks. A photographer’s dream trip.

Eliot said the travel to get to and from Antarctica was long, but one he has wanted to do for many years. He said:

Seeing the emperors is special, few people do, only a very few of the cruise boats have a chance to go that deep into the Weddell Sea. They often fail, so the number of tourists who see the emperors each year cannot be more than 100 to 200.

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Photos of the expedition

More emperor penguins

The heroes of the trip

See more images of the expedition at Eliot’s Flickr page

Read more on why emperor penguins are endangered

Bottom line: EarthSky friend Eliot Herman took a trip to the Antarctic, where he had the opportunity to visit emperor penguins in their colony. Read his report and enjoy his amazing images.

The post Emperor penguins: A report from the Antarctic first appeared on EarthSky.

Oldest known wild bird spotted in the Pacific

An albatross named Wisdom, the oldest known wild bird at 70 years old, at least, has once again returned to the Midway Atoll National Wildlife Refuge in the Pacific. A volunteer spotted the septuagenarian at the refuge on Friday, December 1, 2023. And she looks good for her age!

The U.S. Geological Survey (USGS) first tagged Wisdom at Midway, in the 1950s. The tag bears the designation Z333. Experts estimate that she was hatched at least as early at 1951, if not earlier. That would put her at a minimum of 72 years old.

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Laysan albatrosses

Wisdom is a Laysan albatross, or moli. These birds return to tiny atolls in the Pacific every year starting in October. Because of their long lifespans, they can be a challenge to study. A typical albatross lives for two to three times the length of a biologist’s career.

Plus, albatrosses are difficult to study because they spend up to 90% of their lives in the air, moving from their summer feeding ground in the northern Pacific, to the tiny atolls in the mid-Pacific that are their places to nest.

Albatrosses are ‘near-threatened’

The population of the Laysan albatross falls in the category of “near-threatened.” They’re no longer hunted as they were in the early 1900s. But their numbers haven’t yet recovered.

In 2009, scientists estimated that around 10,000 albatrosses died annually due to poisoning at Midway. Chicks born in nests close to buildings left behind by the Navy ingested lead-based paint chips that led to their deaths.

By August 2018, the U.S. had remediated the lead problem and declared Midway Atoll lead-free.

The U.S. Fish and Wildlife Service has said:

Wisdom’s continued contribution to the fragile albatross population is remarkable and important. Her health and dedication have led to the birth of other healthy offspring, which will help recover albatross populations on Laysan and other islands.

Bottom line: A beloved albatross named Wisdom is the world’s oldest known wild bird. She’s more than 70! And she just returned again to her winter nesting ground.

Read more: New chick for oldest known wild bird Wisdom

The post Oldest known wild bird, Wisdom, is back! first appeared on EarthSky.

What is a green flash?

A sunset walk on a beach – looking west – is a great time to catch a green flash. What is it? The green flash is an optical phenomenon that you can see shortly after sunset or before sunrise. It happens when the sun is almost entirely below the horizon, with the upper edge still visible. For a second or two, that upper rim of the sun will appear green in color (or sometimes blue). It’s a brief flash of the color green, and quite exciting to see, especially if you’ve been looking for one!

Green flashes do play a role in some legends. In fact, it’s said that once you’ve seen a green flash, you’ll never again go wrong in matters of the heart.

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How can you see one?

You just need two things to see a green flash:

1. A clear day with no haze or clouds on the horizon.

2. A distant horizon, and a distinct edge to the horizon. In particular, you can see the green flash from a mountaintop or high building. But usually, people on the beach or in boats see them over the ocean.

Important tip: Don’t look at the sun until it is nearly entirely below the horizon. If you do, you will dazzle (or damage) your eyes and ruin your green flash chances for that day.

Because you need to know exactly where to look along the horizon, and because most of us aren’t up before dawn, green flashes are most often seen after sunset. Diligent observers, however, can see them before dawn, too. And it’s possible to see green flashes over land, too, if your horizon is far enough away.

What makes a green flash?

According to Les Cowley at Atmospheric Optics:

As the sun’s disk diminishes, the green light becomes concentrated and separates from the other colors, creating the brilliant green flash that captivates observers.

Les explains that the green flash is part of a mirage:

Inferior mirages are produced by warm air at the ocean or earth’s surface and an air temperature gradient changing rapidly with height. Rays from a low sun are refracted back upward as they pass between the cool and warm layers. Refraction always tends to deflect rays toward the denser layer. An observer above the layer sees two solar images or parts of them … (1) an erect image from rays that pass relatively undeflected above the warm layer and (2) a lower inverted image from rays mirrored upward by the warm layer. Each sun image is as ‘real’ as the other. The effect is not dissimilar to the mirage seen above a hot road surface.

As the sunset proceeds, the upper and lower images approach, touch and eventually overlap to form an ‘omega’ shaped sun.

A green flash occurs because at a later stage the deflection by the warm layer/cooler air boundary becomes very sensitive to the angle of incidence of the sun’s rays. Small deviations are vertically magnified including the difference in deflection between red and green rays. This amplification provides the separation between green and red that refraction through a normal atmosphere cannot accomplish.

What is the green ray?

The flash can be like a flame that shoots above the horizon. In that case, it’s called a green ray. I’ve seen lots of green flashes, but never a green ray, although I was once walking on a beach in Mexico and turned away just as my companion saw one.

I did not find any photos of flamelike green rays (if you know of one, let me know), but the photo below suggests the beginnings of a ray.

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A green flash on other planets?

Well … Yes! You can also see a green flash on very bright planets – like Venus or Jupiter – from Earth. Check these amazing videos, and don’t miss the comment section below them. People had some very interesting questions to ask, and the authors gave them the answers they were looking for.

Green flash photos from the EarthSky community

A few more green flash photos

More great green flash photos

Bottom line: Learn what a green flash is and how to see one here. Plus, enjoy great photos and watch a video!

The post What’s a green flash and how can I see one? first appeared on EarthSky.

The University College London published this article on December 4, 2023. Reprinted here with permission. Edits by EarthSky.

Einstein’s gravity and quantum mechanics

Modern physics is founded upon two pillars. One is quantum theory, which governs the smallest particles in the universe. The other is Einstein’s theory of general relativity, which explains gravity through the bending of spacetime. But these two theories are in contradiction with each other, and a reconciliation has remained elusive for over a century.

The prevailing assumption has been to modify Einstein’s theory of gravity, or “quantized” to fit within quantum theory. This is the approach of two leading candidates for a quantum theory of gravity, string theory and loop quantum gravity.

But Jonathan Oppenheim at University College London Physics & Astronomy has developed a new theory. In a new paper in the peer-reviewed open-access journal Physical Review X (PRX), he challenges that consensus and takes an alternative approach by suggesting that spacetime may be classical. That is, not governed by quantum theory at all.

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Here’s how Einstein’s gravity and quantum mechanics works

Instead of modifying spacetime, the theory – dubbed a “postquantum theory of classical gravity” – modifies quantum theory. It predicts an intrinsic breakdown in predictability that is mediated by spacetime itself. This results in random and violent fluctuations in spacetime that are larger than envisaged under quantum theory, rendering the apparent weight of objects unpredictable if measured precisely enough.

A second paper, published simultaneously in the peer-reviewed, open-access journal Nature Communications and led by Oppenheim’s former Ph.D. students, looks at some of the consequences of the theory. It also proposes an experiment to test it: to measure a mass very precisely to see if its weight appears to fluctuate over time.

For example, the International Bureau of Weights and Measures in France routinely weighs a 1 kilogram mass, which used to be the 1kg standard. If the fluctuations in measurements of this 1kg mass are smaller than required for mathematical consistency, they can rule out that theory.

A 5,000:1 odds bet

The outcome of the experiment, or other evidence emerging that would confirm the quantum versus classical nature of spacetime, is the subject of a 5,000:1 odds bet between Professor Oppenheim and theoretical physicists Carlo Rovelli and Geoff Penington. Rovelli and Penington are leading proponents of quantum loop gravity and string theory, respectively.

For the past five years, the UCL research group has been stress-testing the theory and exploring its consequences.

Professor Oppenheim said:

Quantum theory and Einstein’s theory of general relativity are mathematically incompatible with each other. So it’s important to understand how this contradiction is resolved. Should spacetime be quantized, or should we modify quantum theory, or is it something else entirely? Now that we have a consistent fundamental theory in which spacetime does not get quantized, it’s anybody’s guess.

The experimental proposal

Co-author Zach Weller-Davies, who, as a Ph.D. student at UCL, helped develop the experimental proposal and made key contributions to the theory itself, said:

This discovery challenges our understanding of the fundamental nature of gravity but also offers avenues to probe its potential quantum nature.

We have shown that if spacetime doesn’t have a quantum nature, then there must be random fluctuations in the curvature of spacetime which have a particular signature that can be verified experimentally.

In both quantum gravity and classical gravity, spacetime must be undergoing violent and random fluctuations all around us, but on a scale which we haven’t yet been able to detect. But if spacetime is classical, the fluctuations have to be larger than a certain scale, and this scale can be determined by another experiment where we test how long we can put a heavy atom in superposition* of being in two different locations.

The analytical and numerical calculations of co-authors Carlo Sparaciari and Barbara Šoda helped guide the project. They expressed hope that these experiments could determine whether the pursuit of a quantum theory of gravity is the right approach.

More about the proposal

Šoda (formerly UCL Physics & Astronomy, now at the Perimeter Institute of Theoretical Physics, Canada) said:

Because gravity is made manifest through the bending of space and time, we can think of the question in terms of whether the rate at which time flows has a quantum nature, or classical nature.

And testing this is almost as simple as testing whether the weight of a mass is constant, or appears to fluctuate in a particular way.

Sparaciari (UCL Physics & Astronomy) said:

While the experimental concept is simple, the weighing of the object needs to be carried out with extreme precision.

But what I find exciting is that starting from very general assumptions, we can prove a clear relationship between two measurable quantities, the scale of the spacetime fluctuations, and how long objects like atoms or apples can be put in quantum superposition of two different locations. We can then determine these two quantities experimentally.

Weller-Davies added:

A delicate interplay must exist if quantum particles such as atoms are able to bend classical spacetime. There must be a fundamental trade-off between the wave nature of atoms, and how large the random fluctuations in spacetime need to be.

Einstein’s gravity and quantum mechanics background

Quantum mechanics. All the matter in the universe obeys the laws of quantum theory, but we only really observe quantum behavior at the scale of atoms and molecules. Quantum theory tells us that particles obey Heisenberg’s uncertainty principle, and we can never know their position or velocity at the same time. In fact, they don’t even have a definite position or velocity until we measure them. Particles like electrons can behave more like waves and act almost as if they can be in many places at once (more precisely, physicists describe particles as being in a “superposition” of different locations).

Quantum theory governs everything from the semiconductors that are ubiquitous in computer chips, to lasers, superconductivity and radioactive decay. In contrast, we say that a system behaves classically if it has definite underlying properties. A cat appears to behave classically: it is either dead or alive, not both, nor in a superposition of being dead and alive. Why do cats behave classically, and small particles quantumly? We don’t know, but the postquantum theory doesn’t require the measurement postulate, because the classicality of spacetime infects quantum systems and causes them to localize.

About gravity

Einstein’s gravity. Newton’s theory of gravity gave way to Einstein’s theory of general relativity (GR), which holds that gravity is not a force in the usual sense. Instead, heavy objects such as the sun bend the fabric of spacetime in such a way that causes Earth to revolve around it. Spacetime is just a mathematical object consisting of the three dimensions of space, and time considered as a fourth dimension. General relativity predicted the formation of black holes and the Big Bang. It holds that time flows at different rates at different points in space, and the GPS in your smartphone needs to account for this to properly determine your location.

Illustration at top

At the top of this article is an artistic version of Figure 1 in the PRX paper. It depicts an experiment in which heavy particles (illustrated as the moon) cause an interference pattern (a quantum effect), while also bending spacetime. The hanging pendulums depict the measurement of spacetime. The actual experiment typically uses Carbon-60, one of the largest known molecules. The UCL calculation indicates that the experiment should also use higher density atoms such as gold. Image via Isaac Young/ University College London. Used with permission.

Physical Review X paper
Nature Communications paper
Public lecture by Professor Jonathan Oppenheim in January 2024
Professor Oppenheim’s academic profile
UCL Physics & Astronomy
UCL Mathematical & Physical Sciences

Bottom line: Einstein’s gravity and quantum mechanics are the two bases for modern physics. But these two theories contradict each other. Have we reached a reconciliation?

Via UCL

The post Einstein’s gravity and quantum mechanics united at last? first appeared on EarthSky.

Clouds that look like waves are rare and beautiful. These clouds – known as Kelvin-Helmholtz clouds, billow clouds, or shear-gravity clouds – might have been the inspiration for Van Gogh’s painting Starry Night. The next time you spot one of these remarkable wave clouds, capture a photograph and submit it to us!

Kelvin-Helmholtz clouds are named for Lord Kelvin and Hermann von Helmholtz, who studied the physics of the instability that leads to this type of cloud formation. A Kelvin-Helmholtz instability forms where there’s a velocity difference across the interface between two fluids: for example, wind blowing over water.

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How to see Kelvin-Helmholtz clouds

When might you get to see these beautiful clouds? Your odds are better on windy days, when there’s a difference in densities of the air – for example, during a temperature inversion – when warm air flows over cooler air. You’re also more likely to see these clouds near sunrise or sunset, another time when the bottom of the clouds are cooler and the air above is warmer. The clouds take on this wave shape when the air above is moving more quickly than the air below, pushing over the tops of the clouds and creating the rolling wave appearance. As you might have guessed, Kelvin-Helmholtz clouds are a sign that aircraft in the area will be experiencing turbulence.

Wave clouds from the EarthSky community

More photos of Kelvin-Helmholtz clouds

Kelvin-Helmholtz clouds from 2 sides of Earth

These photographers both captured Kelvin-Helmholtz clouds on the same day, from two sides of Earth.

Wave clouds on other planets

Bottom line: Clouds that look like waves across the sky are known as Kelvin-Helmholtz clouds. These clouds form from winds moving at two different speeds.

The post Kelvin-Helmholtz clouds look like ocean waves first appeared on EarthSky.

The Audubon Society’s Christmas Bird Count is one of the longest-running citizen science projects. It had a modest beginning on Christmas Day in 1900. And it’s since become a strong data-gathering project to study bird population trends. This year’s count – the 124th – runs from December 14, 2023, to January 5, 2024. You have to sign up in advance, and the signup has already begun. Go here to sign up for the Christmas Bird Count 2023.

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Audubon Christmas Bird Count – how it’s done

The Christmas Bird Count is a carefully run event. Each count site is a 15-mile (24-km) wide circle; you can see what it looks like by zooming in on this map to inspect a region near you. Counts for each circle are organized by a “circle compiler.” On the day of the count (set by the circle’s compiler), people head out to designated routes within a circle to count every species and number of birds that they see and hear during the day. And, if you live within the range of a count site, you can also tally the birds you see in your yard and at the feeder.

To participate in the count – it’s free – you need to sign up with a local circle compiler at the Audubon’s website. If you’re a beginning birder, you’ll be matched up with a more experienced birder. Make sure you register early, because the compiler will need time to organize the event.

In addition, you can share your bird count photographs and experiences on social media with the hashtag #ChristmasBirdCount. We here at EarthSky would love to have you send us your photographs, too!

Audubon Christmas Bird Count history

In some parts of the U.S., there used to be bird-hunting competitions on Christmas Day. However, Frank M. Chapman, an ornithologist at the American Museum of Natural History, came up with an alternative, an activity to count birds in a given area each Christmas to build up a record of their numbers.

That first count was in 1900. Overall, 27 birders conducted counts at 25 sites, tallying about 89 bird species.

Since then, the Christmas Bird Count has come a long way. It’s continued annually since the inaugural event, growing in volunteers and census sites. For instance, the 121st Christmas Bird Count took place from December 14, 2020, to January 5, 2021. That count occurred at 2,459 locations, with 72,815 volunteers in the U.S., Canada, Latin America, the Caribbean and Pacific Islands. Altogether, volunteers observed a total of 2,355 bird species.

What have we learned from these counts?

Additionally, Audubon and other research groups use Christmas Bird Count data to monitor population trends that will help guide conservation efforts. To date, scientists have published more than 300 peer-reviewed studies based on this data. The data is also used by federal agencies to craft policy on bird conservation.

Each annual count provides a snapshot of the birds at a given time and place. It’s hard to draw conclusions from one year to the next, because changes happen gradually. To understand trends, scientists do a statistical analysis of data taken over several years.

Warning signs of environmental degradation show up in declines of bird populations in some types of habitats. For instance, the sharpest declines in bird populations have been in grassland habitats, followed by coastal habitats.

Bird census data also informs scientists about the effects of climate change on wildlife. In a 2014 report, National Audubon predicted how the ranges of 588 species of birds in North America could be affected by climate change. They concluded that more than 314 species could lose over 50% of their current climatic range by 2080.

Bottom line: Audubon’s 124th Christmas Bird Count will take place from December 14, 2023, to January 5, 2024. You can join in to help collect important data about birds. Find out how to join in the Audubon Christmas Bird Count.

The post Audubon Christmas Bird Count signup has begun first appeared on EarthSky.

Ofer Cohen, UMass Lowell

The Earth’s magnetic field plays a big role in protecting people from hazardous radiation and geomagnetic activity that could affect satellite communication and the operation of power grids. And the magnetic field moves and flips.

Scientists have studied and tracked the motion of the magnetic poles for centuries. The historical movement of these poles indicates a change in the global geometry of Earth’s magnetic field. It may even indicate the beginning of a field reversal – a flip – between the north and south magnetic poles.

I’m a physicist who studies the interaction between the planets and space. While the north magnetic pole moving a little bit isn’t a big deal, a reversal could have a big impact on Earth’s climate and our modern technology. But these reversals don’t happen instantaneously. Instead, they occur over thousands of years.

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Magnetic field generation

So how are magnetic fields like the one around Earth generated?

Moving electric charges are what generate magnetic fields. A material that enables charges to move easily in it is called a conductor. Metal is one example of a conductor; people use it to transfer electric currents from one place to the other. The electric current itself is simply negative charges called electrons moving through the metal. This current generates a magnetic field.

The Earth’s liquid iron core has layers of conducting material. Currents of charges move throughout the core. And the liquid iron is also moving and circulating in the core. These movements generate the magnetic field.

Irregularities in a magnetic field

Earth isn’t the only planet with a magnetic field; gas giant planets like Jupiter have a conducting metallic hydrogen layer that generates their magnetic fields.

The movement of these conducting layers inside planets results in two types of fields. Larger motions, such as large-scale rotations with the planet, lead to a symmetric magnetic field with a north and a south pole … similar to a toy magnet.

These conducting layers may have some local irregular motions due to local turbulence or smaller flows that do not follow the large-scale pattern. These irregularities will manifest in some small anomalies in the planet’s magnetic field or places where the field deviates from being a perfect dipole field.

These small-scale deviations in the magnetic field can actually lead to changes in the large-scale field over time. And they can potentially cause a complete reversal of the polarity of the dipole field, where the north becomes south and vice versa. The designations of “north” and “south” on the magnetic field refer to their opposite polarities; they’re not related to geographic north and south.

The Earth’s magnetosphere, a protective bubble

The Earth’s magnetic field creates a magnetic “bubble” called the magnetosphere above the uppermost part of the atmosphere, the ionosphere layer.

The magnetosphere plays a major role in protecting people. It shields and deflects damaging, high-energy, cosmic-ray radiation, which is created in star explosions and moves constantly through the universe. The magnetosphere also interacts with solar wind, which is a flow of magnetized gas from the sun.

The magnetosphere and ionosphere’s interaction with magnetized solar wind creates what scientists call space weather. Usually, the solar wind is mild and there’s little to no space weather.

However, there are times when the sun sheds large magnetized clouds of gas – or coronal mass ejections – into space. If these coronal mass ejections make it to Earth, their interaction with the magnetosphere can generate geomagnetic storms. Geomagnetic storms can create auroras, which happen when a stream of energized particles hits the atmosphere and lights up.

During space weather events, there’s more hazardous radiation near Earth. This radiation can potentially harm satellites and astronauts. Space weather can also damage large conducting systems, such as major pipelines and power grids, by overloading currents in these systems.

Space weather events can also disrupt satellite communication and GPS operation, which many people rely on.

Field flips

Scientists map and track the overall shape and orientation of the Earth’s magnetic field using local measurements of the field’s orientation and magnitude and, more recently, models.

The location of the north magnetic pole has moved by about 600 miles (965 km) since it was first measured in 1831. The migration speed has increased from 10 miles per year to 34 miles per year (16 km to 54 km) in more recent years. This acceleration could indicate the beginning of a field reversal, but scientists really can’t tell with less than 200 years of data.

The Earth’s magnetic field reverses on time scales that vary between 100,000 to 1,000,000 years. Scientists can tell how often the magnetic field reverses by looking at volcanic rocks in the ocean.

These rocks capture the orientation and strength of the Earth’s magnetic field when they are created. So dating these rocks provides a good picture of how the Earth’s field has evolved over time.

Field reversals happen fast from a geologic standpoint, though slow from a human perspective. A reversal usually takes a few thousand years. But during this time, the magnetosphere’s orientation may shift and expose more of the Earth to cosmic radiation. These events may change the concentration of ozone in the atmosphere.

Scientists can’t tell with confidence when the next field reversal will happen, but we can keep mapping and tracking the movement of Earth’s magnetic north.

Ofer Cohen, Associate Professor of Physics and Applied Physics, UMass Lowell

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Earth’s magnetic field helps protect life on Earth. But the magnetic poles wander, and they flip polarity every 100,000 to 1,000,000 years.

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