[The question is more tricky than you might realise. Jan]

To the naked eye, the night sky reveals only one moon. But how many moons have ever orbited Earth?

How many moons does Earth have? The answer seems obvious: Earth has only one moon. It’s even in the name: the moon. At first, Earth’s moon needed no other name, because for millennia, we didn’t know any other natural satellite existed. But over centuries of astronomy and space exploration, we’ve discovered hundreds of moons in the solar system, and there may be more than you think circling our planet.

"The moon" holds the title of Earth’s only solid, permanent moon, said Gábor Horváth, an astronomer at Eötvös Loránd University in Hungary. But it’s not the only object to be pulled into Earth’s orbit; a host of near-Earth objects and dust clouds are also caught in Earth’s gravity. These often-temporary satellites technically qualify as minimoons, quasi-satellites or ghost moons.

So the question of how many moons Earth has is more complicated than you might think. The number has changed over time — from zero, to one, to sometimes multiple moons.

Back in Earth’s early days, about 4.5 billion years ago, our planet was moonless. Then, around 4.4 billion years ago, a Mars-size protoplanet called Theia struck Earth. Large chunks of Earth’s crust were catapulted into space. The rocky debris came together — maybe in just a few hours — to form the moon, according to 2022 research published in The Astrophysical Journal Letters.

Other "moons" that measure just a few feet across have been far more temporary, captured by Earth’s gravity for short periods before escaping back into space. In 2006, there was the up-to-20-foot-wide (6 meters) asteroid 2006 RH120, a space rock that lingered for 18 months and was the first observed long-term capture of an asteroid into Earth’s orbit. And 2020 CD3, a space rock up to 11.5 feet (3.5 m) across, left Earth’s orbit in March 2020 after spending three years as our mini second moon. In 2020, scientists also spotted SO 2020, a minimoon that drifted back into space in early 2021. Turns out, though, that SO 2020 wasn’t a natural moon; it was the remains of a rocket booster from the 1960s.

An example of a recent minimoon was a space rock up to 11.5 feet (3.5 m) across known as 2020 CD3 which was in Earth’s orbit for three years before leaving.

For 13 hours in 2015, scientists thought they had found a new temporary moon orbiting Earth. But they quickly realized their mistake when it was revealed that the "moon" was merely the European Space Agency’s Gaia space telescope, prompting the International Astronomical Union’s Minor Planet Center to issue a retraction.

In addition to the moons that come and go from Earth’s orbit, there are space objects that NASA calls quasi-satellites, such as the asteroid 3753 Cruithne. These space rocks orbit the sun so similarly to Earth that they stick with our planet throughout its 365-day orbit. The quasi-moon Kamo’oalewa — suspected of being an artifact of the actual moon — is driven primarily by the sun’s gravity but appears to orbit Earth in a corkscrew-like path.

Some space objects, such as asteroid 2010 TK7, earn the title of "moon" because they get caught in the unique gravity of the sun-Earth or Earth-moon systems. The gravity of the two larger bodies creates regions of centripetal force, called Lagrange points, that hold smaller objects in place in gravitationally stable points in space, according to NASA. Two Lagrange points, L4 and L5, form an equilateral triangle with Earth. Effectively, the objects captured in these Lagrange points, called Trojans, fall in line with Earth and join its orbit around the sun.

"Parallel to the formation of the solid Moon and stabilization of its orbit around the Earth, the Lagrange points L4 and L5 have also arisen, and have started to collect [and] trap the interplanetary dust particles," Horváth told Live Science in an email. Some astronomers call these particle clouds "ghost moons." They’re also called Kordylewski clouds, after the Polish astronomer who first reported them in the 1960s. At first, many scientists were unconvinced, but since then, research by astronomers such as Horváth has confirmed that dust clouds are accumulating at these Lagrange points.

However, these ghost moons will never form a more solid moon, because the dust can’t conglutinate, or join or adhere together, Horváth said. And while the Lagrange points remain constant, the material in them is dynamic, constantly entering and exiting the dust cloud.

Source: https://www.livescience.com/how-many-moons-does-earth-have

[I don't know how common quakes are on other planets and moons. I know the moon experiences some kind of Moon Quakes. But I think that quakes on Earth are much bigger than anything you see on other planets. Plate Tectonics and the movement of continents is UNIQUE to Earth, and it's actually very weird. Jan]

Tectonic activity triggered by the gravitational influence of the gas giants causes landslides of icy debris.

Moonquakes may be smoothing out the surfaces of moons orbiting gas giant planets Jupiter and Saturn, new research has revealed. The findings could solve a long-standing mystery regarding why many of these icy moons have such smooth terrain.

Scientists have known for some time that some of the moons that orbit the gas giants Jupiter and Saturn, the largest and second-largest planet in the solar system respectively, are geologically active. This is the result of the massive gravitational influence of these planets that stretches and squeezes the moons orbiting them, triggering moonquakes that crack the moon’s crusts and icy surfaces.

This new research implies these moonquakes can also trigger landslides that help create smooth terrains. The link between moonquakes and landslides indicates how the surfaces of these moons evolve.

Steep ridges surrounded by relatively smooth areas are a common sight across the landscapes of the Jovian moons Europa and Ganymede, as well as Saturn’s moon Enceladus. While scientists have speculated that these features are the work of liquid flowing from icy volcanoes, quite how the process works at low temperatures on these frigid moons that are inhospitable to liquids, has been a puzzle.

The explanation put forward in this new research doesn’t require the presence of liquid on the surface of these icy moons, however.

The team came to the surprising conclusion when they set about measuring the dimensions of these ridges, thought to be steep slopes caused by the surface breaking along a fault line with one side dropping in what scientists call "tectonic fault scarps." They then applied the measurements to seismic models which allowed them to estimate the power of moonquakes in the history of these moons.

This revealed that some of these seismic events would have been strong enough to hoist up debris that then rolls downhill, spreading out as it does so and smoothing out the landscape of the moons.

"We found the surface shaking from moonquakes would be enough to cause surface material to rush downhill in landslides. We’ve estimated the size of moonquakes and how big the landslides could be," research lead author and University of Arizona in Tucson graduate student Mackenzie Mills, said in a statement. "This helps us understand how landslides might be shaping moon surfaces over time."

The research conducted by Mills during a series of summer internships at NASA’s Jet Propulsion Laboratory in Southern California will get a major boost when NASA’s Europa Clipper mission heads to Europa in 2024.

The Europa Clipper mission will orbit Jupiter and conduct about 50 flybys of Europa in the process, collecting images and scientific data with its payload of nine science instruments. This should also help planetary scientists determine if there is a deep liquid ocean beneath the icy shell of the Jovian moon and if it possesses the conditions needed to support life.

"It was surprising to find out more about how powerful moonquakes could be and that it could be simple for them to move debris downslope," Europa Clipper project scientist and research co-author Robert Pappalardo, said in the statement.

The team said it was particularly surprising to discover the strength of tectonic activity and quakes on Enceladus, as this moon of Saturn has less than 3% of the surface area of Europa and about 1/650 that of Earth.

"Because of that moon’s small gravity, quakes on tiny Enceladus could be large enough to fling icy debris right off the surface and into space like a wet dog shaking itself off," Pappalardo said. "We hope to gain a better understanding of the geological processes that have shaped icy moons over time and to what extent their surfaces may still be active today."

The team’s research is published in the journal Icarus.

Source: https://www.space.com/moonquakes-shape-surfaces-gas-giant-moons

Scientists recently discovered an asteroid that tags along with Earth during its yearly journey around the sun.

Dubbed 2023 FW13, the space rock is considered a "quasi-moon" or "quasi-satellite," meaning it orbits the sun in a similar time frame as Earth does, but is only slightly influenced by our planet’s gravitational pull. It is estimated to be 50 feet (15 meters) in diameter — roughly equivalent to three large SUVs parked bumper to bumper. During its orbit of the sun, 2023 FW13 also circles Earth, coming within 9 million miles (14 million kilometers) of our planet. For comparison, the moon has a diameter of 2,159 miles (3,474 km) and comes within 226,000 miles (364,000 km) of Earth at the closest point of its orbit, according to NASA.

2023 FW13 was first observed in March by the Pan-STARRS observatory, which is located atop the volcanic mountain Haleakalā in Hawaii. The asteroid’s existence was then confirmed by the Canada-France-Hawaii Telescope in Hawaii and two observatories in Arizona before being officially listed on April 1 by the Minor Planet Center at the International Astronomical Union, a network of scientists responsible for designating new planets, moons and other objects in the solar system.

Some estimates suggest that 2023 FW13 has been Earth’s cosmic neighbor since at least 100 B.C. and that the space rock will continue to follow this orbital path until around A.D. 3700, Adrien Coffinet, an astronomer and journalist who first categorized the asteroid as a quasi-moon after modeling its orbit, told Sky & Telescope.

"It seems to be the longest quasi-satellite of Earth known to date," Coffinet said.

Following 2023 FW13’s initial discovery in March, space observers dug into the data and found observations of the asteroid dating all the way back to 2012, according to Live Science’s sister site Space.com.

Despite hovering relatively close to Earth, this quasi-satellite likely isn’t on a collision course with our planet.

"The good news is, such an orbit doesn’t result in an impacting trajectory ‘out of the blue,’" Alan Harris, an astronomer at the Space Science Institute, told Sky & Telescope.

This is not Earth’s only quasi-companion; a different quasi-satellite known as Kamo’oalewa was discovered in 2016. The rock sticks similarly close to our planet during its orbit around the sun, and a 2021 study suggested that this asteroid could actually be a fragment of Earth’s moon.

Source: https://www.livescience.com/space/the-moon/new-quasi-moon-discovered-near-earth-has-been-travelling-alongside-our-planet-since-100-bc

[I didn't even know that humans existed in Europe 300,000 years ago! That is very old. That's even older than the period of time when humans supposedly left Africa! It raises many questions. Jan]

Footprints belonging to Homo heidelbergensis adults and children suggest that these human relatives foraged and played on the shores of a lake where prehistoric beasts gathered to drink.

In a forest clearing of birch and pine trees in what is today central Europe, herds of long-extinct beasts once gathered to drink on the shores of an ancient lake. Now, researchers have confirmed that early human relatives and their children foraged and bathed among them.

Three rare, 300,000-year-old footprints from a Lower Paleolithic (around 3 million to 300,000 years ago) fossil site in northwestern Germany reveal that Homo heidelbergensis, an extinct species of human that existed from about 700,000 to 200,000 years ago, co-existed with prehistoric elephants and rhinos, whose footprints were also found at the site. While a 2018 study in the journal Scientific Reports documented a similar neighborly relationship between early humans and prehistoric beasts in Ethiopia from 700,000 years ago, this is the first footprint evidence of H. heidelbergensis from Germany and only the fourth record of the species’ footprints worldwide.

"These three footprints represent a significant ‘direct’ proof of the hominin presence on the site," Flavio Altamura, an archeologist at the University of Tübingen in Germany and lead author of a study describing the fossils, told Live Science in an email. While one footprint clearly belonged to an adult, the others were much smaller. "Since two footprints are related to young individuals, this is also proof of the existence of children on the spot," Altamura said.

The discovery is remarkable because signs of children at prehistoric sites are scarce. Most of the evidence researchers have about the earliest periods of humanity comes from tools, human remains and food waste in the form of animal bones, Altamura explained. "You have to look for children’s bones, that are very rare, and it is very hard to link tools and food waste with children’s activity. So it is very difficult to say something about their behavior and the kind of life they were [leading]."

A picture of the 300,000-year-old hominin footprints discovered at a Paleolithic site in nortwesten Germany.

The newly found footprints provide clues about what it was like to be a child 300,000 years ago. "This is a rare snapshot of childhood in prehistory," Altamura said.

The footprints reveal aspects of our human relatives’ daily lives, which researchers describe in a study published May 12 in the journal Quaternary Science Reviews. The findings show that long-extinct "Heidelberg people" dwelled on the shores of an ancient lake among herds of the largest land animals at the time — prehistoric elephants called Palaeoloxodon antiquus that had straight tusks and weighed up to 13 tons (12 metric tons).

The researchers also unearthed tracks belonging to a rhinoceros, which they identified as Stephanorhinus kirchbergensis or S. hemitoechus. They are the first footprints of either species ever found in Europe.

The human footprints were probably left during a small family outing, Altamura said. "We may suggest that a small hominin group that included children was walking among elephants and other species on the muddy shore of an ancient lake, perhaps looking for and collecting food, or bathing, or just playing there."

These are not the oldest H. heidelbergensis children’s footprints unearthed among animal prints, however. A similar collection of human footprints and animal tracks was unearthed between 2013 and 2015 at a 700,000-year-old archeological site in Ethiopia called Melka Kunture. There, a cluster of tracks belonging to 11 adults and children potentially as young as 12 months old suggested that children were present when tools were made and animals butchered.

"Children and adult footprints were found on the border of a pond where other animals congregated and where hippos were butchered by hominins, suggesting that children were assisting adults and learning since their first years how to survive in the then wild environment," Altamura, who co-authored the 2018 study of the Ethiopian fossils, said.

Source: https://www.livescience.com/archaeology/300000-year-old-footprints-reveal-extinct-humans-went-on-a-lakeside-family-outing-among-giant-elephants-and-rhinos

Researchers at a Tokyo university say their vaccine slowed the ageing process in mice, and could even aid the treatment of ageing-related diseases.

What if you could live forever? It’s a question long pondered by fictional supervillains and Silicon Valley billionaires alike.

Now researchers in Japan say they may have taken a step toward boosting human longevity with successful trials of a vaccine against the cells that contribute to the ageing process.

In laboratory trials, a drug targeting a protein contained in senescent cells – those which have naturally stopped reproducing themselves – slowed the progression of frailty in older mice, the researchers from Tokyo’s Juntendo University said.

The vaccine also successfully targeted the senescent cells in fatty tissue and blood vessels, suggesting it could have a positive impact on other medical conditions linked to ageing.

"We can expect that (the vaccine) will be applied to the treatment of arterial stiffening, diabetes and other ageing-related diseases," Juntendo professor Toru Minamino told Japan’s Jiji news agency.

What is cellular senescence?

Cells become senescent when they stop duplicating themselves, often in response to naturally-occurring damage to their DNA. Cellular senescence is thought to contribute to the ageing process itself, as well as ageing-related diseases like Alzheimer’s and some cancers.

"Senescent cells secrete a series of factors that disrupt the function of the tissue," Dr Salvador Macip, head of the University of Leicester’s Mechanisms of Cancer and Ageing Lab, told Euronews Next.

"They ‘call’ cells from the immune system, in theory to be cleared by them (but that eventually fails) and create a chronic low level inflammation, mixed with fibrosis," Macip said.

Macip was part of an international team of academics from universities in the UK, Spain, Nigeria and Saudi Arabia that published research on another method of tackling senescent cells in October this year.

"The biological process of ageing is very complex, therefore it is unlikely that one single strategy will completely stop it or reverse it. However, there are probably many ways to slow it down, and clearing senescent cells seems to be one of the easiest and potentially more effective," he said.

The limit on lifespan

In laboratory tests, preventing the build-up of senescent cells extended the lifespan of mice by 15 per cent, Macip told Euronews Next. Other, similar experiments have achieved as much as a 35 per cent increase, he said.

But before you get too excited, it’s worth bearing in mind that researchers still don’t know how much a living creature’s lifespan can be extended.

"This is a very interesting question, and one that we still have not agreed upon. Some believe there is a ‘hard’ limit for human lifespan (around 130 years is the current estimate), while others think that, on paper, immortality should be feasible," Macip said.

"It’s still early to know how much life can be extended and whether there’s a limit or not".

We may not have to wait too long for an answer, though.

"The field of anti-ageing research is advancing very fast. In the last decade, there have been many key discoveries," Macip said.

"The person that will take the first anti-ageing pill has probably already been born".

Source: https://www.euronews.com/next/2021/12/14/can-we-live-forever-new-anti-ageing-vaccine-could-bring-immortality-one-step-closer

The James Webb Space Telescope (JWST) has discovered the first evidence that millions of supermassive stars up to 10,000 times the mass of the sun may be hiding at the dawn of the universe.

Born just 440 million years after the Big Bang, the stars could shed light on how our universe was first seeded with heavy elements. Researchers, who dubbed the giant stars "celestial monsters," published their findings May 5 in the journal Astronomy and Astrophysics.

"Today, thanks to the data collected by the James Webb Space Telescope, we believe we have found a first clue of the presence of these extraordinary stars," lead study author Corinne Charbonnel, an astronomy professor at the University of Geneva in Switzerland, said in a statement.

Related: The early universe was crammed with stars 10,000 times the size of our sun, new study suggests

The researchers found chemical traces of the gigantic stars inside globular clusters — clumps of tens of thousands to millions of tightly packed stars, many of which are among the most ancient to have ever formed in our universe. Roughly 180 globular clusters dot our Milky Way galaxy and, because they are so old, serve astronomers as windows through time into the earliest years of our universe.

Mysteriously, some of the stars in these clusters have wildly different proportions of elements (oxygen, nitrogen, sodium and aluminum) despite forming at roughly the same time and from the same gas and dust clouds 13.4 billion years ago.

Astronomers believe this elemental variety could be explained by the existence of supermassive stars — cosmic giants born in the denser conditions of the early universe that burned their fuel at much higher temperatures, producing heavier elements that subsequently "polluted" smaller infant stars (which usually consist of much lighter elements).

But finding these stars has proven difficult. Anywhere between 5,000 to 10,000 times the size of our sun, the fiery giants burned at temperatures of 135 million degrees Fahrenheit (75 million degrees Celsius). As bigger, brighter and hotter stars die out the fastest, these cosmic monsters have long since met their demise in extremely violent explosions called hypernovas.

"Globular clusters are between 10 and 13 billion years old, whereas the maximum lifespan of superstars is two million years. They therefore disappeared very early from the clusters that are currently observable. Only indirect traces remain," co-author Mark Gieles, a professor of astrophysics at the University of Barcelona, said in the statement.

To spot the scattered chemical residue of the ancient monsters, the researchers trained the JWST’s infrared camera on the galaxy GN-z11, which is one of the most distant and ancient galaxies ever discovered, sitting 13.3 billion light-years away from Earth. Different chemicals absorb and emit light at different frequencies, so by breaking down the light coming from different globular clusters found across GN-z11, the astronomers discovered that not only were its stars tightly packed but they were surrounded by high levels of nitrogen.

"The strong presence of nitrogen can only be explained by the combustion of hydrogen at extremely high temperatures, which only the core of supermassive stars can reach," Charbonnel said.

Having found the first clues for the celestial monsters, the researchers will look across more globular clusters in more galaxies to see if their discovery holds elsewhere.

Source: https://www.livescience.com/space/cosmology/james-webb-telescope-finds-evidence-of-celestial-monster-stars-the-size-of-10000-suns-lurking-at-the-dawn-of-time

The James Webb Space Telescope took its first close look at a "mini-Neptune" — the most common type of planet beyond our solar system — and found signs of water.

Astronomers have finally peered past the clouds on the exoplanet GJ 1214b, a mini-Neptune planet around a star about 40 light-years away. Mini-Neptunes, like a shrunken down version of the familiar gas giant, are a common type of planet in our galaxy — but because there isn’t one in our own solar system, these worlds have largely remained a curiosity for scientists.

Previous observations of the distant planet were foiled by thick cloud layers, but the powerful James Webb Space Telescope’s (JWST) infrared heat vision allowed astronomers to find a new view through the haze. The results, published May 10 in the journal Nature, reveal that GJ 1214b has an atmosphere made of steam, hinting at its past as a possible "water world," according to NASA researchers.

"For the last almost decade, the only thing we really knew about this planet was that the atmosphere was cloudy or hazy," Rob Zellem, an exoplanet researcher at NASA’s Jet Propulsion Lab, said in a statement. The team used JWST’s Mid-Infrared Instrument (MIRI) to map the temperature of the planet as it moved through its orbit, capturing information on both its day and night sides and enabling astronomers to figure out what it’s made of.

The temperature on GJ 1214b shifted dramatically from day to night, getting as hot as 535 degrees Fahrenheit (280 degrees Celsius) and then cooling down by more than 100 degrees F at night. Imagine a day on Earth with sweltering heat during the day, and then a blizzard overnight — that’s what a 100-degree difference would look like here! On GJ 1214b, this huge temperature swing indicates that the planet’s atmosphere can’t be just light hydrogen molecules; instead, there has to be something else like water or methane. Researchers see this finding as an interesting clue into the planet’s past, since the atmosphere doesn’t match what the star is made of.

GJ 1214b "either lost a lot of hydrogen, if it started with a hydrogen-rich atmosphere, or it was formed from heavier elements to begin with — more icy, water-rich material," lead study author Eliza Kempton, a University of Maryland astronomer, said in the statement. "The simplest explanation, if you find a very water-rich planet, is that it formed farther away from the host star," she added.

Astronomers still have a lot left to figure out about GJ 1214b, but they hope to observe more mini-Neptunes with JWST in the near future. According to Kempton, they hope to figure out a "consistent story" for how mini-Neptunes are created, and how this particular one ended up with so much water.

Source: https://www.livescience.com/space/exoplanets/james-webb-telescope-discovers-ancient-water-world-in-nearby-star-system

[There's a photo of it at the source link below as well as a map of where it travels. Jan]

Over the last few weeks, an enormous balloon has been spotted circling Earth’s Southern Hemisphere in the upper reaches of the atmosphere, sparking fears that it may be a spy balloon like the UFOs that were shot down above North America in February.

But the massive floating bubble is actually NASA’s latest telescope, the Super Pressure Balloon Imaging Telescope (SuperBIT). And rather than spying on unsuspecting people below, the telescope is peering into the cosmos above in search of dark matter.

The giant balloon, which is wider than a football field, was launched on April 16 from Wānaka, New Zealand and has since completed more than two full revolutions around the Southern Hemisphere — the longest continuous flight for a balloon-borne telescope, according to a NASA statement(opens in new tab).

On May 6, photographer Erwin Enrique Sandoval captured a crisp image of SuperBIT around 25 miles (40 kilometers) above Coyhaique in southern Chile. "We could see it high in the afternoon sky," Sandoval told Spaceweather.com(opens in new tab). "It was very large."

SuperBIT’s primary goal is to search for evidence of dark matter by taking detailed images of galaxies in order to spot signs of gravitational lensing — the phenomenon where light from a distant galaxy gets magnified as it travels through gravitationally warped space-time around a closer galaxy — that could provide clues about the invisible yet abundant matter’s true identity.

A new study, released April 20 in the journal Nature Astronomy(opens in new tab), revealed that light from oddly-warped "Einstein rings" could shed light on dark matter’s true identity.

At its lofty altitude, SuperBIT sits above 99.2% of Earth’s atmosphere, which means there is little to no air to obscure its view of the stars, according to the SuperBIT website(opens in new tab). At this height, the telescope can also capture images by day or night.

Astronomers believe the data collected by SuperBIT is comparable in quality to the Hubble Space Telescope, according to Spaceweather.com. And the balloon-borne telescope has already captured several stunning shots(opens in new tab) of distant galaxies.

But astronomy is not the only possible use for giant balloons like this. In June 2020, space tourism company Space Perspective released its plans to eventually take civilians to the edge of space using similar balloons.

Keen-eyed observers and astronomy enthusiasts could have plenty more chances to catch a glimpse of the balloon. "Hopefully, we’ll complete many more revolutions about the hemisphere over the next several weeks," Debbie Fairbrother(opens in new tab), chief of NASA’s Scientific Balloon Program Office, said in the statement. (A single revolution could take anywhere between one and three weeks depending on wind patterns.)

Source: https://www.livescience.com/space/astronomy/weird-balloon-circling-the-southern-hemisphere-isnt-a-spy-craft-its-nasas-newest-telescope

[However, to be exact, it wasn't big. It was only 1 foot long but it was totally bizarre. Jan]

Here’s the video: https://www.youtube.com/watch?v=frnio8eSFyk

Astronomers have observed a radiation belt outside the solar system for the first time, imaging high-energy particles trapped by a magnetic field around an ultra-cool dwarf star around 18 light-years from Earth.

The newfound radiation belt is double-lobed, just like the radiation belts that encircle Jupiter, the largest planet in the solar system. But if the dwarf star’s radiation belt were placed next to that of Jupiter, it would be 10 million times brighter.

The radiation is in the form of persistent, intense radio emissions. Imaging revealed the presence of a cloud of high-energy electrons trapped in the magnetic field of the dwarf star, which is known as LSR J1835+3259.

"We are actually imaging the magnetosphere of our target by observing the radio-emitting plasma  —  its radiation belt  —  in the magnetosphere," research lead author and University of California, Santa Cruz postdoctoral fellow Melodie Kao said in a statement(opens in new tab). "That has never been done before for something the size of a gas giant planet outside of our solar system."

Related: Listen to the terrifying rumble of Earth’s magnetic field being assaulted by a solar storm

The first image of a radiation belt outside the solar system, which was captured using 39 radio telescopes to create a virtual telescope spanning the globe from Hawaii to Germany.

The first image of a radiation belt outside the solar system, which was captured using 39 radio telescopes to create a virtual telescope spanning the globe from Hawaii to Germany. (Image credit: Melodie Kao, Amy Mioduszewski)
The image was captured by the team using a network of 39 radio telescopes, which combined to form a single virtual telescope called the High Sensitivity Array.

LSR J1835+3259 was the only object beyond the solar system that Kao was confident could be observed with enough detail to resolve its radiation belts. And, because the dwarf star has a mass that lies between low-mass stars and brown dwarfs — objects often referred to as "failed stars" because they lack the mass needed to initiate nuclear fusion at their cores — the new observations could help astronomers find the dividing line between small stars and large planets.

"While the formation of stars and planets can be different, the physics inside of them can be very similar in that mushy part of the mass continuum connecting low-mass stars to brown dwarfs and gas giant planets," Kao said.

Strong magnetic fields form a magnetic bubble around a planet called a magnetosphere, which can trap and accelerate charged particles to speeds approaching that of light. Many planets in the solar system have magnetospheres, as does the sun. Even one solar system moon — the huge Jovian satellite Ganymede  —  has a magnetosphere.

Magnetospheres come with different strengths and different characteristics, however. For example, the magnetosphere of Mercury, the closest planet to the sun, has only around 1% the strength of Earth’s magnetic bubble, which is strong enough to protect our planet’s atmosphere and life from highly energetic charged particles from the sun. After the sun, Jupiter has the strongest magnetic field in the solar system.

All the planets in the solar system with magnetic fields also have radiation belts consisting of trapped high-energy charged particles around them. While the radiation belts of Earth, known as the Van Allen Belts, are donut-shaped bands of high-energy particles from solar wind, the majority of the particles trapped by magnetic fields around Jupiter creating double lobe-shaped radiation belts come from its volcanic moon Io.

Regardless of their origin, these trapped particles are deflected by magnetic fields toward the poles of planets, generating auroras. On Earth, these take the form of the northern and southern lights here, or the aurora borealis and the aurora australis, respectively.

The image of LSR J1835+3259 taken by Kao and her team also marks the first time for a body beyond the solar system that the location of an object’s aurora and that of its radiation belts has been successfully differentiated.

Auroras can be used to measure the strength of magnetospheres, if not their shape, so the findings could help determine the strength of the magnetic fields of other dwarf stars, something which is largely unknown currently. Building the theoretical understanding of the magnetic fields of these intermediate-mass objects could, in turn, shed light on the magnetospheres of exoplanets.

"Now that we’ve established that this particular kind of steady-state, low-level radio emission traces radiation belts in the large-scale magnetic fields of these objects, when we see that kind of emission from brown dwarfs  —  and eventually from gas giant exoplanets  —  we can more confidently say they probably have a big magnetic field, even if our telescope isn’t big enough to see the shape of it," Kao said.

Because Earth’s magnetosphere has been so crucial in protecting life on our planet and allowing it to evolve, scientists theorize that magnetic fields around exoplanets may be key to understanding the habitability of worlds beyond the solar system.

"This is a critical first step in finding many more such objects and honing our skills to search for smaller and smaller magnetospheres, eventually enabling us to study those of potentially habitable, Earth-size planets," research co-author Evgenya Shkolnik, an astrophysics professor at Arizona State University, said in the same statement.

The team’s research was published on Monday (May 15) in the journal Nature.(opens in new tab)

Source: https://www.space.com/dwarf-star-radiation-belt-first-outside-solar-system