Earth makes a tiny seismic rumble every 26 seconds.
Is the pulsating caused by ocean waves, volcanoes, or something else completely? Theories abound.
The "microseism" doesn’t seem to be hurting anything and has not been a high priority.
Why is Earth pulsating every 26 seconds, and why can’t scientists explain it after 60 years? This is an enigma wrapped in a periodically predictable mystery motion. It could be a harmonic phenomenon, a regular seismic chirp caused by the sun’s energy, or a beacon drawing scientists to its source to begin a treasure hunt.
In the early 1960s, a geologist named Jack Oliver first documented the pulse, also known as a "microseism," according to Discover. Oliver, who worked at Columbia University’s Lamont-Doherty Geological Observatory at the time, heard the noise, but didn’t have the advanced instruments seismologists have now at his disposal.
Since then, scientists have spent a lot of time listening to the pulse and even finding out where it comes from: “a part of the Gulf of Guinea called the Bight of Bonny,” Discover says.
Some researchers think the pulse has a kind of prosaic cause. Under the world’s oceans, the continental shelf acts as a gigantic wave break—it’s the boundary off the very far edge of, for example, the North American continental mass where the highest part of the plate finally falls off into the deep abyssal plain. Scientists have theorized that as waves hit this specific place on the continental shelf in the Gulf of Guinea, this regular pulse is produced.
If that sounds improbable, consider all the different shapes of drums, from timpani to bass drums to bongos that you hit with your hands. It’s not impossible that just one shape of continental shelf “drum” would create the right harmonic bang to rattle the Earth. If that’s true, we’re probably lucky it’s just one.
But other researchers think the cause is a volcano that’s also very near the critical spot: “That’s because the pulse’s origin point is suspiciously close to a volcano on the island of São Tomé in the Bight of Bonny,” Discover explains. And there’s a similar volcanic microseism that’s already well documented in Japan.
It seems like reams of new scientific research emerge every day, but the mystery pulse is a good reminder that so much remains to be discovered. Scientists have studied the pulse and debate its origin, but it just hasn’t reached a tipping point of interest to be solved. Discover explains that researchers have likely been studying higher-priority seismic events instead, which makes sense.
This year, for example, seismologists have an important opportunity to study a much quieter Earth during global quarantine. That could mean they all redouble efforts on high-priority subjects, or it could mean that the right listener at the right time could finally understand the 26-second chirp once and for all. In a perfect world, we could have both.
It was a getaway attempt worthy of Ian Fleming, but in the end, a suspected US fraudster proved he was no James Bond.
Matthew Piercey, 44, a California man accused of financial crimes, briefly evaded justice when the FBI tried to arrest him on Monday morning.
He first fled by car and then used a sea scooter to hide from agents underwater in a frigid lake.
Agents watched his bubbles on the surface for around 25 minutes before he emerged and was handcuffed.
He is accused of leading a $35m (£27m) Ponzi scheme at his local church.
Sea scooters, also known as diver propulsion vehicles, are underwater devices that can pull a person wearing scuba gear. They were used for the underwater battle in the 1965 James Bond film Thunderball and have been employed by real-life militaries around the world.
Officials said that when they moved in to arrest Mr Piercey he fled in a pickup truck, twice driving off the road. He was then seen jumping in to the lake near the city of Redding with a strange device in his hand.
Police later learned that the model he used, a Yamaha 350Li, can reach speeds of 4mph (6.5km/h) and can travel at depths of 100ft underwater.
"You never know what is going through someone’s mind when they’re being pursued by the FBI," said lawyer Josh Kons, who is representing several victims of the alleged fraud.
"And we kept investigating, and all of a sudden today, here he is trying to escape into a lake, using a submersible device."
After Mr Piercey emerged, police medics examined him for hypothermia and gave him dry clothes they had collected from his wife, according to the Sacramento Bee news website.
Investigators say that he and his business partner Kenneth Winton used funds invested in their companies, Family Wealth Legacy and Zolla, to pay for personal expenses, and that few liquid assets remained for them to return to clients.
Mr Piercey is charged with wire fraud, mail fraud, money laundering, and witness tampering and is facing 20 years in prison.
On July 3, 1969, just 17 days before Neil Armstrong and Buzz Aldrin walked on the lunar surface, the USSR made its second attempt to test-fire its own moon rocket, known as N1.
No official announcement about the secret mission had ever been made, but in subsequent passes over the Soviet test range in Tyuratam, Kazakhstan, U.S. spy satellites glimpsed utter devastation at one of the two launch pads known to host the moon rocket.
The Soviet Union didn’t know it at the time, but its hopes for reaching the moon also ended on that charred launch pad in 1969.
The story of the Soviet N1 rocket and the wider lunar program in the USSR is still shrouded in mystery, especially compared to the Apollo program. To this day, historians debate how and why the pioneering Soviet space program suddenly fell behind in the race to the moon and how far behind it had been at the moment when Armstrong and Aldrin set foot on another world.
The truth is no one element completely doomed the Soviet Union’s lunar program. The Kremlin’s resting on its laurels after winning the race into Earth’s orbit with Sputnik and Gagarin certainly played a role. Internal rivalries between leaders of the Soviet space program—Sergei Korolev, Valentin Glushko and Vladimir Chelomei—didn’t help things, either.
But as early as April 1961, U.S. policy makers had already singled out the lunar expedition as something that the U.S. was likely to achieve ahead of the USSR, simply because of the American economic and technological superiority.
Add to that the lukewarm support of the civilian space program by the Soviet military, which in large part held purse strings of the rocket industry, and it becomes clear that the Soviet engineers never had a chance to beat NASA to the moon.
Even half a century after the events, we’re still learning pieces of the extensive and multi-faceted Soviet effort to put humans on the moon.
Only in 2015 did the successor to the OKB-1 design bureau, which developed the giant N1 rocket, release details illustrating the growing pains of the Soviet lunar exploration program, reminiscent of the torturous path to the final mission design in the Apollo project.
The documents from April 1963 testify how the Soviet engineers just completed an analysis of 26 different scenarios for the lunar expedition and were only able to narrow them down to four diverse architectures, which still needed more detailed studies before the final plan could be picked. In retrospect, it’s stunning to see how far from the final architecture, these four finalist scenarios had been with the plan’s less-than-feasible hopes for multiple launches of super-rockets, yet-to-be-tried docking procedures, and ambitious refueling in Earth’s orbit.
For comparison, in the middle of 1962, the fathers of the Apollo project had already favored the rendezvous in the lunar orbit as the key element of the flight scenario and a single-launch architecture, thus clearing the way for a fast-paced development of the Saturn V rocket for the Apollo missions.
The Rocket That Started the Space Race
Even at this early paper phase—when serious investments of money and materiel had not been required from the Kremlin—the Soviet engineers were almost a year behind the U.S., and it went only downhill from there for the Soviets.
Various disputes on the use of propellant and design of the future moon rocket and other strategic disagreements within the industry put complicated and delayed the Soviet lunar program. Only in 1964, had Soviet engineers gotten necessary political go-ahead to join the moon race, but it was already too late.
In the next four years, myriad technical problems and flawed flight tests kept widening the gap between Apollo and its Soviet rival.
When the time came for production, the USSR also faced geographical disadvantages. For example, the launch site in Tyuratam was located far from sea ports, meaning the assembly of booster stages for the moon rocket would have to be moved to the arid steppes of Kazakhstan—along with an army of workers.
Finally, the killing blow to the Kremlin’s lunar efforts came from the main propulsion system of the N1 rocket. Initially, there were various plans to equip the N1 with engines up to 600 tons of thrust, but the lack of necessary machinery and time forced designers to settle for a much smaller 150-ton engine. It meant that a total of 24—and when that proved not enough, 30—engines would have to be working in a precisely choreographed fashion to lift the monstrous vehicle off the pad.
Building the large static-firing facility, which would allow engineers to tune up the capricious multi-engine cluster on the ground, was also abandoned to save time and money. So when the brand-new engines first met together, they were supposed to work on the actual rocket in real flight.
Lunik 1 manned lunar landing module, it was intended to operate in conjunction with the zond 9 spacecraft in 1971.
The Lunik 1 manned lunar lander planned for the Soviet lunar program. It never flew.
During the first launch attempt on February 21, 1969, the vehicle failed after one minute and eight seconds in flight due to a propulsion system failure. The leaders of the project were disappointed but not discouraged—after all, nobody died, the launch pad remained intact, and the rocket actually demonstrated some ability to fly (at least up an altitude of 30 kilometers).
Indeed, many Soviet veterans of the N1 project lived through spectacular failures of so many preceding rockets that this could almost be seen as good news. So the Soviet team pressed ahead with the second N1 launch attempt as soon as possible.
The second N1 rocket, designated 5L, reached the pad in the summer of 1969, after Apollo 9 and Apollo 10 had already completed dress rehearsal missions ahead of the actual lunar landing attempt—an American victory loomed on the horizon. As the sixth Saturn V rocket slated for the Apollo 11 mission was undergoing checks at Cape Canaveral, the second N1 vehicle reached the launch pad.
The N1 rocket No. 5L blasted off into the night from July 3 to July 4, 1969.
As it climbed to an altitude of around 100 meters, just 10.5 seconds after liftoff, some bright pieces ominously fell off from its tail section. The colossus then seemingly froze in mid-air and started tilting to its side. At the tip of the rocket, the emergency escape engines fired and pulled the capsule, meant to carry the two-person crew, into darkness. With its flight control system paralyzed by an engine explosion, the giant rocket was unable to steer itself downrange and crashed back onto the launch pad with most of its propellant.
The massive explosion almost completely wiped out half of the two-pad launch complex, a project that took several years to complete. Some pieces from the rocket were apparently found as far as six miles away and windows were reported to be blown off in buildings located nearly four miles from the launch pad.
A Done Deal
The failure of the second launch sealed the Soviet’s fate in the moon race and raised the question if a Soviet cosmonaut would ever walk on the moon. In the next several years, N1 made two more unsuccessful (though not as devastating) launch attempts before the Soviet government shut down the program in June 1974.
The Soviet space program continued making great contributions to humanity’s exploration of space, including its famous Soyuz rocket, but the dream of a Soviet cosmonaut on the moon died on a Kazakhstan launchpad in the summer of ’69.
The twin infants’ double burial was unearthed in Krems am Wachtberg, Austria.
An ancient grave in Austria may represent the oldest burial of twins on record, a new study finds.
The 31,000-year-old burial dates to the Upper Paleolithic (a period lasting from 40,000 to 10,000 years ago), also known as the Old Stone Age. One of the infants died shortly after childbirth, while his twin brother lived for about 50 days, or just over 7 weeks, according to analyses of both babies.
A third infant, a 3-month-old, interred in a burial about 5 feet (1.5 meters) away is likely their cousin, according to the research, published online Nov. 6 in the journal Communications Biology.
Researchers found the twins’ oval-shaped burial at the archaeological site of Krems-Wachtberg, on the bank of the Danube River by the town center of Krems in 2005. The twin infants’ remains were covered with ochre, a red pigment often used in ancient burials across the world. The double burial also contained 53 beads made out of mammoth ivory that were likely once threaded on a necklace, and a perforated fox incisor and three perforated mollusks, which were possibly necklace pendants, the researchers said. A mammoth shoulder blade placed over the burial protected the small bodies interred beneath it over the millennia.
The nearby burial of the other infant also contained ochre, as well as a 3-inch-long (8 centimeters) mammoth-ivory pin, which may have fastened a leather garment together at the time of burial, the researchers said.
The finding made headlines shortly after its discovery, and researchers even created a replica of the twins’ burial, which went on display at the Natural History Museum Vienna in 2013. However, scientists still had much to learn about the ancient burial. So, in the new project, an interdisciplinary group of researchers teamed up to decipher the relationship between these three infants and to determine their sex and age at death.
The study is the first on record to use ancient DNA to confirm twins in the archaeological record, the researchers said. And not just any twins, but identical twins.
This is the "earliest proof of a twin birth," study senior researcher Ron Pinhasi, an associate professor in the Department of Evolutionary Biology at the University of Vienna, said in a statement (translated from German with Google Translate). Researchers don’t know how common twin births were during the Upper Paleolithic (the rate fluctuates by region and time), but today, twins (both identical and fraternal) happen in about one in 85 births, while identical twins are born in about one in 250 births.
"To discover a multiple burial from the Paleolithic period is a specialty in itself," study lead researcher Maria Teschler-Nicola, a biologist at the Natural History Museum Vienna, said in the statement. "The fact that sufficient and high-quality old DNA could be extracted from the fragile child’s skeletal remains for a genome analysis exceeded all of our expectations and can be compared to a lottery ticket."
A genetic analysis of the third infant revealed that he was a third-degree male relative, likely a cousin, the researchers found.
The twins’ bodies were covered with the red pigment ochre.
Those newborn lines, as well the infants’ skeletal development, suggested the twins were either full, or nearly full-term, babies. It appears that the infants’ hunter-gatherer group buried the first twin, then reopened the grave when they buried his brother.
This finding confirms the cultural-historical practice of reopening a grave for the purpose of reburial, which had never been documented before in a Paleolithic burial, the researchers said.
The team also analyzed chemical elements, including isotopes of carbon, nitrogen and barium, in the tooth enamel, revealing that each of the twins was breastfed. Even though the twins’ cousin survived for three months, "stress lines" in his teeth suggest that he had feeding difficulties, perhaps because his mother had a painful breast infection known as mastitis, or maybe because she didn’t survive the birth.
It’s unknown exactly why these infants died, but the deaths of these twins and their cousin were likely painful events for this Paleolithic hunter-gatherer group, who set up camp and buried their babies by the Danube so long ago. "The babies were obviously of particular importance to the group and highly respected and esteemed," Teschler-Nicola told Live Science. The extraordinary burials "seems to imply that the death of the babies was a great loss for the community and their survival."
[Nature is freaky. Here is an eel eating it's way out of a bird's stomach. The eels often do it with fish. They don't take shit! Nature is nasty. Jan]
A snake eel fighting for its life pulled an "alien" move by bursting out of the stomach of a heron that had just swallowed it whole, according to photos snapped by an amateur photographer in Delaware.
The photos show the snake eel, its head dangling in midair, as the heron — looking surprisingly unbothered — flies onward.
The unusual event attracted a lot of attention among the local predators, said Sam Davis, an engineer from Maryland who took the photos on the Delaware shore. Several juvenile eagles and a fox were following the heron, possibly hoping to scavenge a meal in case the heron or the snake eel didn’t make it, he said.
When Davis first spotted the bizarre flight, he thought that a snake or eel had bitten the heron’s neck. Davis was about 75 yards to 100 yards (68 to 91 meters) away from the animals, but he had a telephoto lens for long-range photography, and so he shot photos as he watched the heron fly about and even land in the water with the eel still attached to it. "The heron didn’t seem to act much differently," Davis told Live Science. "It was in the water and flying around."
Meanwhile, the eel was arching its body, "so i guess it was still alive at some point," he said.
It wasn’t until Davis returned home and edited the photos that he realized that the snake eel wasn’t biting the heron. After enlarging the photos, "I could see the eel, you could see its eyes," he said. "It was actually coming out the other end" — headfirst.
Snake eels are usually known for burrowing out of the stomachs of fish.
The snake eel arches its body. It’s unknown if it survived. (Image credit: Sam Davis)
The photos show "a pretty amazing sight," said John Pogonoski, an ichthyologist with the Australian National Fish Collection at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), who wasn’t involved with the heron and snake eel’s encounter. "I would think this is either very rare or very rarely seen in a bird species, at least as far as I am aware."
Earlier this year, Pogonoski and his colleagues published a study in the journal Memoirs of the Queensland Museum on snake eels (a fish from the family Ophichthidae), detailing how snake eels can burrow out of the guts of fish that prey on them. "But usually they don’t get very far," he told Live Science in an email. Once swallowed, snake eels can use their hard heads or tails to bust out of the digestive tract, but usually end up in the predator’s body cavity, muscle tissues or swim bladder. Once trapped, snake eels often "become ‘mummified’ or ‘encysted’ [closed up in a cyst] and die rather than escape," he said.
In one instance, "a co-author of the paper once discovered a live snake eel inside a fish he caught when he cleaned the fish to eat it," Pogonoski said.
Davis never learned what happened to the heron and snake eel photographed in Delaware in 2011 (he uploaded the photos to a wildlife site only a few months ago). When he left the shore, the heron was still flying around with the snake eel hanging below it.
According to Pogonoski, "the heron possibly survived, it didn’t look too inconvenienced, but would depend on how well the wound healed and if it was able to avoid an infection."
As for the snake eel, it "would only have survived if it was dropped over or very close to water with a salinity it could normally tolerate," he said.
[Nature is freaky. Here is an eel eating it's way out of a bird's stomach. The eels often do it with fish. They don't take shit! Nature is nasty. Jan]
A snake eel fighting for its life pulled an "alien" move by bursting out of the stomach of a heron that had just swallowed it whole, according to photos snapped by an amateur photographer in Delaware.
The photos show the snake eel, its head dangling in midair, as the heron — looking surprisingly unbothered — flies onward.
The unusual event attracted a lot of attention among the local predators, said Sam Davis, an engineer from Maryland who took the photos on the Delaware shore. Several juvenile eagles and a fox were following the heron, possibly hoping to scavenge a meal in case the heron or the snake eel didn’t make it, he said.
When Davis first spotted the bizarre flight, he thought that a snake or eel had bitten the heron’s neck. Davis was about 75 yards to 100 yards (68 to 91 meters) away from the animals, but he had a telephoto lens for long-range photography, and so he shot photos as he watched the heron fly about and even land in the water with the eel still attached to it. "The heron didn’t seem to act much differently," Davis told Live Science. "It was in the water and flying around."
Meanwhile, the eel was arching its body, "so i guess it was still alive at some point," he said.
It wasn’t until Davis returned home and edited the photos that he realized that the snake eel wasn’t biting the heron. After enlarging the photos, "I could see the eel, you could see its eyes," he said. "It was actually coming out the other end" — headfirst.
Snake eels are usually known for burrowing out of the stomachs of fish.
The snake eel arches its body. It’s unknown if it survived. (Image credit: Sam Davis)
The photos show "a pretty amazing sight," said John Pogonoski, an ichthyologist with the Australian National Fish Collection at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), who wasn’t involved with the heron and snake eel’s encounter. "I would think this is either very rare or very rarely seen in a bird species, at least as far as I am aware."
Earlier this year, Pogonoski and his colleagues published a study in the journal Memoirs of the Queensland Museum on snake eels (a fish from the family Ophichthidae), detailing how snake eels can burrow out of the guts of fish that prey on them. "But usually they don’t get very far," he told Live Science in an email. Once swallowed, snake eels can use their hard heads or tails to bust out of the digestive tract, but usually end up in the predator’s body cavity, muscle tissues or swim bladder. Once trapped, snake eels often "become ‘mummified’ or ‘encysted’ [closed up in a cyst] and die rather than escape," he said.
In one instance, "a co-author of the paper once discovered a live snake eel inside a fish he caught when he cleaned the fish to eat it," Pogonoski said.
Davis never learned what happened to the heron and snake eel photographed in Delaware in 2011 (he uploaded the photos to a wildlife site only a few months ago). When he left the shore, the heron was still flying around with the snake eel hanging below it.
According to Pogonoski, "the heron possibly survived, it didn’t look too inconvenienced, but would depend on how well the wound healed and if it was able to avoid an infection."
As for the snake eel, it "would only have survived if it was dropped over or very close to water with a salinity it could normally tolerate," he said.
Half of the stars in our galaxy that are similar to the sun could be home to an Earth-like planet capable of supporting life.
A team led by Steve Bryson at NASA’s Ames Research Center in California analysed data from the Kepler space telescope, searching for rocky planets within the habitable zone of stars the same size as our sun. The habitable zone is found at the distance from a star where it isn’t too hot or too cold for liquid water to exist.
“It’s hard not to be entranced,” says Linda Ivany at Syracuse University, New York. “It’s as tall as I am.”
D. maximum’s unusual shell shape makes it difficult to unravel its biology, but Ivany and her colleague, Emily Artruc, have now uncovered hints that individuals might have had very long lives. The evidence comes from chemical signatures locked away in samples taken at regular intervals along a 50-centimetre-long section of D. maximum shell.
When she and Artruc examined the carbon and oxygen isotopes along the shell, they found a repeating pattern in the isotopic signatures that they suspect reflects the annual release of methane from the sea floor. This annual pattern matched up with the sculptural ridges, or ribs, perpendicular to the length of the shell. This suggests that D. maximum added one new rib to its shell each year. “These shells grow by accretion, adding a new increment annually,” says Ivany.
Given that a 1.5-metre-long shell contains many dozen ribs, that leads to an obvious conclusion. “The only scenario that seems to work is to make this thing 200 years old,” says Ivany, who presented the research at an online meeting of the Geological Society of America last week.
At first glance, a 200-year-old shellfish might seem unremarkable, given that some modern shellfish can live more than twice as long. But D. maximum was a cephalopod, and all modern cephalopods live fast and die young. Octopuses and squid – even the gigantic forms – live no more than about 5 years. Nautilus, shelled cephalopods, can survive into their twenties. “These are not centenarians,” says Ivany.
Why D. maximum might have had such a long lifespan isn’t clear. It lived around Antarctica, where food must have been difficult to come by during the long and dark winter. Ivany speculates that the ammonite might have had a slow metabolism to cope, and lived a long life as a side effect. Alternatively, a long lifespan might have been an adaptation to maximise the chances of reproducing successfully in such a challenging environment.
Either way, the new evidence for the length of the lifespan will lead to a deeper understanding of the living paperclip’s lifestyle, says Ivany. “If you know something about an organism’s lifespan, you learn a lot about its ecology.”
75 years on from the atomic bombing of Hiroshima, more than 13,000 nuclear warheads are still scattered across the world from silos in Montana to isolated corners of European airbases and even to the ocean depths where ballistic missile submarines lurk as a deterrent nearly impossible to detect. Hiroshima was the first of two atomic bombings in 1945 and it involved a 15-kiloton device while the weapon used in the attack on Nagasaki three days later had a 22 kiloton yield. Modern nuclear warheads are far more powerful with the U.S. Trident missile yielding a 455 kiloton warhead while Russia’s SS ICBM has an 800 kiloton yield. Together, the United States and Russia possess more than 90 percent of the world’s nuclear weapons with a stockpile of 8,000 between them, according to the Federation of American Scientists. Active and inactive warheads in military custody are included in that total but it excludes strategic warheads currently deployed at bases for heavy bombers and on intercontinental ballistic missiles.
Even though 8,000 seems like an awfully large number (which it is), it represents a huge reduction on the number of warheads in existence at the height of the Cold War. This infographic shows how stockpiles evolved, particularly when various arms limitation treaties are taken into account. The number of warheads fell significantly in the wake of the Intermediate-Range Nuclear Forces Treaty which was signed by the U.S. and USSR in 1987 at a time when both countries possessed more than 60,000 nuclear weapons. The trend towards disarmament continued after the Berlin Wall came down and accelerated when the Soviet Union collapsed. Despite the decline, it isn’t all good news as states are now modernizing their existing stockpiles, adding new types, new delivery systems and committing to possessing the weapons long-term.
Developments in Washington D.C. have added to those worries with the Trump administration leaving the Intermediate-Range Nuclear Forces Treaty and now threatening to pull out of New START. That agreement limits the U.S. and Russia to 1,550 deployed nuclear missiles each. The reason cited by President Trump is that China has to be part of any such agreements in the future and so far, Beijing has categorically ruled out any participation. The treaty will expire in February, weeks after the presidential inauguration. Trump has already abandoned the Iran nuclear accord and he recently took the U.S. out of the Open Skies Treaty, blaming Russia for a lack of compliance.
Earth orbits the sun like a ship sailing in circles around its anchor. But what if someone — or something — cut that ship loose? Unbound from any star or solar system, what would become of a tiny world flying helplessly and heedlessly through interstellar space? What happens when a planet goes rogue?
Scientists suspect that billions of free-floating or "rogue" planets may exist in the Milky Way, but so far only a handful of candidates have turned up among the 4,000-or-so worlds discovered beyond our solar system. Most of these potential rogue planets appear to be enormous, measuring anywhere from two to 40 times the mass of Jupiter (one Jupiter is equivalent to about 300 Earths). But now, astronomers believe they’ve detected a rogue world like no other: a tiny, free-floating planet, roughly the mass of Earth, gallivanting through the gut of the Milky Way.
This discovery, reported today (Oct. 29) in the Astrophysical Journal Letters, may mark the smallest rogue planet ever detected, and it could help prove a long-standing cosmic theory. According to the study authors, this little world could be the first real evidence that free-floating, Earth-sized planets may be some of the most common objects in the galaxy.
"The odds of detecting such a low-mass object are extremely low," lead study author Przemek Mroz, a postdoctoral scholar at the California Institute of Technology, told Live Science in an email. "Either we were very lucky, or such objects are very common in the Milky Way. They may be as common as stars."
Most exoplanets in our galaxy are visible only because of their host stars. In a literal sense, stars provide the light that allows astronomers to directly observe alien worlds. When a planet is too small or too distant to be seen directly, scientists can still detect it from the slight gravitational pull it exerts on its host star (called the radial velocity method) or by the flickering that occurs when a planet passes in front of the star’s Earth-facing side (the transit method).
Rogue planets, by definition, have no star to light their way — or to light a telescope’s way to them. Instead, detecting rogue planets involves a facet of Einstein’s theory of general relativity known as gravitational lensing. Through this phenomenon, a planet (or even more massive object) acts as a cosmic magnifying glass that temporarily bends the light of objects behind it from Earth’s perspective.
"If a massive object passes between an Earth-based observer and a distant source star, its gravity may deflect and focus light from the source," Mroz explained in a statement. "The observer will measure a short brightening of the source star."
An artist’s impression of a gravitational microlensing event by a free-floating, or rogue, planet. In microlensing, gravity from an object causes the light from a background source to bend, an astronomical phenomenon that shows up as distortions in images taken from Earth.
An artist’s impression of a gravitational microlensing event by a free-floating, or rogue, planet. In microlensing, gravity from an object causes the light from a background source to bend, an astronomical phenomenon that shows up as distortions in images taken from Earth.
The smaller that light-bending object is, the briefer the star’s perceived brightening will be. While a planet several times the mass of Jupiter might create a brightening effect that lasts a few days, a measly planet the mass of Earth will brighten the source star for only a few hours, or less, the researchers said. This exceptionally rare occurrence is called "microlensing."
"Chances of observing microlensing are extremely slim," Mroz added in the statement. "If we observed only one source star, we would have to wait almost a million years to see the source being microlensed."
Fortunately, Mroz and his colleagues weren’t observing just one star for their study — they were watching hundreds of millions of them. Using observations from the Optical Gravitational Lensing Experiment (OGLE), a star survey based at the University of Warsaw in Poland that has turned up at least 17 exoplanets since 1992, the team stared into the center of the Milky Way, looking for any signs of microlensing.
In June 2016, they witnessed the shortest microlensing event ever seen. The star in question, located roughly 27,000 light-years away in the densest part of the galaxy, brightened for just 42 minutes. Calculations showed that the offending object was not bound to any star within 8 astronomical units (AU, or eight times the average distance from Earth to the sun), suggesting it was almost certainly a tiny planet on the run, ejected from its home solar system after a brush with a much more massive object.
Depending on how far away the planet is from the source star (it’s impossible to tell with current technology), the rogue world is likely between one-half and one Earth mass. In either case, this roaming world would be the lowest-mass rogue planet ever detected. According to Mroz, that’s a "huge milestone" for the science of planet formation.
"Theories of planet formation have predicted that the majority of free-floating planets should be of Earth mass or smaller, but this is the first time that we could find such a low-mass planet," Mroz said. "It’s really amazing that Einstein’s theory allows us to detect a tiny piece of rock floating in the galaxy."
Many more tiny pieces of rock may soon follow, study co-author Radek Poleski of the University of Warsaw told Live Science. Future planet-hunting telescopes, like NASA’s Nancy Grace Roman Space Telescope (slated to launch in the mid-2020s), will be much more sensitive to the galaxy’s teensiest microlensing events than the nearly 30-year-old OGLE experiment is, Poleski said. If orphan planets of roughly Earth’s mass are indeed some of the most common denizens of the galaxy, it shouldn’t be long before many more of them turn up.
An artist’s impression of Diplomoceras maximum
