The Telegraph reports: Peter Scott-Morgan stands, wide-eyed and tearful. "Good. Grief." he says quietly. "I was unprepared for the emotion... It's quite extraordinary. It really is." Using an exoskeleton, Scott-Morgan is experiencing what it is like to stand for the first time in months after being diagnosed with motor neurone disease in 2017, the same incurable condition that killed scientist Stephen Hawking.

The remarkable step, however, is just the first in the 62-year-old's bold journey to control his disease by becoming the world's first, full-fledged cyborg. "Think of it as a science experiment," he laughs. "This is cyborg territory, and I intend to be a human guinea pig to see just how far we can turn science fiction into reality." Eventually, Scott-Morgan wants the exoskeleton to encase his upper body, giving him superhuman strength and the ability to tower above "flesh and blood" humans. A mind-reading computer will be plugged directly into his brain, expressing his thoughts almost instantly. Meanwhile, his paralyzed face will be replaced by a hyper-realistic avatar that will move in time with a speech synthesizer...

Scott-Morgan says he isn't deteriorating but becoming a new version of himself — one that will eventually pave the way for a breed of humans that can augment their capabilities using technology... Instead of answering a question by laboriously typing out individual letters using a gaze tracker, in a similar way to Hawking, he will rely on the AI to provide a full and instant response. Eventually, the machine will speak for itself using phrases it has learned from Scott-Morgan — crossing a controversial line in what it means to be human....

Someday, the scientist hopes he can exist completely outside his physical body, with his personality, traits and knowledge downloaded on to a machine.

Citizen scientists have spotted almost 100 of our sun's nearest neighbors. Space.com reports: In a new study, members of the public -- including both professional scientists and volunteers -- discovered 95 brown dwarfs (celestial objects too big to be considered planets and too small to be considered stars) near our sun through the NASA-funded citizen science project Backyard Worlds: Planet 9. They made this discovery with the help of astronomers using the National Science Foundations National Optical-Infrared Astronomy Research Laboratory. Brown dwarfs are unusual celestial objects -- much heavier than planets but not massive enough to become stars. The celestial objects can be seriously hot (think thousands of degrees Fahrenheit), but these 95 newly-discovered neighbors are surprisingly cool. Some of these weird worlds are even relatively close to Earth's temperature and could be cool enough to have water clouds in their atmospheres, according to the statement.

Voyager 2 has been traveling through space for 43 years, and is now more than 11 billion miles from Earth. But every so often, something goes wrong. From a report: At the end of January, for instance, the robotic probe executed a routine somersault to beam scientific data back to Earth when an error triggered a shutdown of some of its functions. "Everybody was extremely worried about recovering the spacecraft," said Suzanne Dodd, who is the Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The mission's managers on our planet know what to do when such a fault occurs. Although it takes about a day and a half to talk to Voyager 2 at its current distance, they sent commands to restore its normal operations.

But starting on Monday for the next 11 months, they won't be able to get word to the spry spacecraft in case something again goes wrong (although the probe can still stream data back to Earth). Upgrades and repairs are prompting NASA to take offline a key piece of space age equipment used to beam messages all around the solar system. The downtime is necessary because of a flood of new missions to Mars scheduled to leave Earth this summer. But the temporary shutdown also highlights that the Deep Space Network, essential infrastructure relied upon by NASA and other space agencies, is aging and in need of expensive upgrades.

A plan to release over 750 million genetically modified mosquitoes into the Florida Keys in 2021 and 2022 received final approval from local authorities, against the objection of many local residents and a coalition of environmental advocacy groups. The proposal had already won state and federal approval. CNN reports: Approved by the Environment Protection Agency in May, the pilot project is designed to test if a genetically modified mosquito is a viable alternative to spraying insecticides to control the Aedes aegypti. It's a species of mosquito that carries several deadly diseases, such as Zika, dengue, chikungunya and yellow fever. The mosquito, named OX5034, has been altered to produce female offspring that die in the larval stage, well before hatching and growing large enough to bite and spread disease. Only the female mosquito bites for blood, which she needs to mature her eggs. Males feed only on nectar, and are thus not a carrier for disease.

The mosquito also won federal approval to be released into Harris County, Texas, beginning in 2021, according to Oxitec, the US-owned, British-based company that developed the genetically modified organism (GMO). The Environmental Protection Agency granted Oxitec's request after years of investigating the impact of the genetically altered mosquito on human and environmental health. "This is an exciting development because it represents the ground-breaking work of hundreds of passionate people over more than a decade in multiple countries, all of whom want to protect communities from dengue, Zika, yellow fever, and other vector-borne diseases," Oxitec CEO Grey Frandsen said in a statement at the time. However, state and local approval for the Texas release has not been granted, said Sam Bissett, a communication specialist with Harris County Public Health.

The EPA permit requires Oxitec to notify state officials 72 hours before releasing the mosquitoes and conduct ongoing tests for at least 10 weeks to ensure none of the female mosquitoes reach adulthood. However, environmental groups worry that the spread of the genetically modified male genes into the wild population could potentially harm threatened and endangered species of birds, insects and mammals that feed on the mosquitoes.

schwit1 shares a report from Phys.Org: A new study led by University of Illinois, Urbana-Champaign astronomy and physics professor Brian Fields explores the possibility that astronomical events were responsible for an extinction event 359 million years ago, at the boundary between the Devonian and Carboniferous periods. The paper is published in the Proceedings of the National Academy of Sciences. The team concentrated on the Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light -- evidence of a long-lasting ozone-depletion event.

"Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question," Fields said. "Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone." The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. "But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period," said graduate student and study co-author Jesse Miller.

A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years. However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. "This is entirely possible," Miller said. "Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion." "I'm sure somebody has a GRB or similar in their 2020 pool of what could go wrong next," adds schwit1.

New submitter louisfreeman shares a report from Space.com: A newly discovered car-sized asteroid just made the closest-known flyby to Earth without hitting our planet. On Sunday (Aug. 16), the asteroid, initially labeled ZTF0DxQ and now formally known to astronomers as 2020 QG, swooped by Earth at a mere 1,830 miles (2,950 kilometers) away. That gives 2020 QG the title of closest asteroid flyby ever recorded that didn't end with the space rock's demise. What's slightly concerning is the fact that the flyby wasn't expected.

The Palomar Observatory didn't detect the zooming asteroid until about six hours after the object's closest approach. "The asteroid approached undetected from the direction of the sun," Paul Chodas, the director of NASA's Center for Near Earth Object Studies, told Business Insider. "We didn't see it coming."

New submitter HotSyncer shares a report from Phys.Org: [I]n a paper published on Aug. 17, in Nature Nanotechnology, Stanford scientists demonstrate a new approach to slow light significantly, much like an echo chamber holds onto sound, and to direct it at will. Researchers in the lab of Jennifer Dionne, associate professor of materials science and engineering at Stanford, structured ultrathin silicon chips into nanoscale bars to resonantly trap light and then release or redirect it later. These "high-quality-factor" or "high-Q" resonators could lead to novel ways of manipulating and using light, including new applications for quantum computing, virtual reality and augmented reality; light-based WiFi; and even the detection of viruses like SARS-CoV-2.

"We're essentially trying to trap light in a tiny box that still allows the light to come and go from many different directions," said postdoctoral fellow Mark Lawrence, who is also lead author of the paper. "It's easy to trap light in a box with many sides, but not so easy if the sides are transparent -- as is the case with many Silicon-based applications."

AleRunner writes: In the first half of 2020, Sweden has recorded its highest death total in 150 years. "In total, 51,405 Swedes died in the six-month period, a higher number than in any year since 1869, when 55,431 people died, partly as a result of a famine," reports The Guardian. In what may be a reaction to this failure, which makes Sweden the worst coronavirus country in Scandinavia, Sweden has announced a change to their new contact-tracing policy. The Local explains: "If you test positive for the coronavirus you may now be given instructions to call people with whom you have been in contact and may have infected, instead of healthcare staff doing the job for you, or it not being done at all."

In early June, Sweden switched from its failed "herd immunity" strategy to a contact-tracing strategy and has since seen a strong fall in new infections, though with a recent slight increase. The new contact-tracing strategy will be critical for the return of the Swedish economy with Sweden currently facing travel restrictions from Scandinavian neighbors such as Finland, whilst other Scandinavian and Baltic countries are already open for trade and tourism. Swedes will be hoping that the adjustment of their new coronavirus strategy will be a signpost for other countries rather than the warning of their old strategy.

Not so long ago, in June, we discussed how Sweden's old strategy had made Sweden a Pariah state and in May we had discussed how Sweden's old strategy caused many deaths whilst failing to deliver immunity.

A California resident has tested positive for plague, marking the state's first human case of the disease in five years, according to health officials. Live Science reports: The case was confirmed on Monday in a resident of South Lake Tahoe, according to a statement from the El Dorado County Department of Health and Human Services. The individual is described as an "avid walker" who may have been bitten by an infected flea while walking their dog in the Tahoe Keys area or along the "Truckee River Corridor" north of Highway 50, the statement said.

"Plague is naturally present in many parts of California, including higher elevation areas of El Dorado County," Dr. Nancy Williams, the El Dorado County public health officer, said in the statement. "It's important that individuals take precautions for themselves and their pets when outdoors, especially while walking, hiking and/or camping in areas where wild rodents are present. Human cases of plague are extremely rare but can be very serious." The patient is currently recovering at home under the care of medical professionals, the statement said.

Bodhammer shares a report from the University of Michigan: In a step closer to skyscrapers that serve as power sources, a team led by University of Michigan researchers has set a new efficiency record for color-neutral, transparent solar cells. The team achieved 8.1% efficiency and 43.3% transparency with an organic, or carbon-based, design rather than conventional silicon. While the cells have a slight green tint, they are much more like the gray of sunglasses and automobile windows.

The new material is a combination of organic molecules engineered to be transparent in the visible and absorbing in the near infrared, an invisible part of the spectrum that accounts for much of the energy in sunlight. In addition, the researchers developed optical coatings to boost both power generated from infrared light and transparency in the visible range -- two qualities that are usually in competition with one another. The color-neutral version of the device was made with an indium tin oxide electrode. A silver electrode improved the efficiency to 10.8%, with 45.8% transparency. However, that version's slightly greenish tint may not be acceptable in some window applications.

Both versions can be manufactured at large scale, using materials that are less toxic than other transparent solar cells. The transparent organic solar cells can also be customized for local latitudes, taking advantage of the fact that they are most efficient when the sun's rays are hitting them at a perpendicular angle. They can be placed in between the panes of double-glazed windows. [The team is] working on several improvements to the technology, with the next goal being to reach a light utilization efficiency of 7% and extending the cell lifetime to about 10 years. They are also investigating the economics of installing transparent solar cell windows into new and existing buildings. The research has been published in the journal Proceedings of the National Academy of Sciences.

fahrbot-bot shares a report from ScienceAlert: NASA is actively monitoring a strange anomaly in Earth's magnetic field: a giant region of lower magnetic intensity in the skies above the planet, stretching out between South America and southwest Africa. This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers. The space agency's satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.

The primary source is considered to be a swirling ocean of molten iron inside Earth's outer core, thousands of kilometers below the ground. A huge reservoir of dense rock called the African Large Low Shear Velocity Province, located about 2,900 kilometers (1,800 miles) below the African continent, disturbs the field's generation, resulting in the dramatic weakening effect -- which is aided by the tilt of the planet's magnetic axis. It's not just moving, however. Even more remarkably, the phenomenon seems to be in the process of splitting in two, with researchers this year discovering that the SAA appears to be dividing into two distinct cells, each representing a separate centre of minimum magnetic intensity within the greater anomaly. Just what that means for the future of the SAA remains unknown, but in any case, there's evidence to suggest that the anomaly is not a new appearance.

Researchers have demonstrated that they can make a working 3D-printed copy of a key just by listening to how the key sounds when inserted into a lock. Slashdot reader colinwb writes: While you cannot hear the shape of a drum it seems you can hear the shape of one type of key from the sound it makes in the lock. That says it all really, but [here's how Soundarya Ramesh and her team at the National University of Singapore accomplished this feat]: "[The NUS team developed and tested what it calls SpiKey, an end-to-end attack technique for, as its name suggests, spying on Yale/Schlage type keys and using signal processing software to infer their correct shapes.] Once they have a key-insertion audio file, SpiKey's inference software gets to work filtering the signal to reveal the strong, metallic clicks as key ridges hit the lock's pins [and you can hear those filtered clicks online here]. These clicks are vital to the inference analysis: the time between them allows the SpiKey software to compute the key's inter-ridge distances and what locksmiths call the 'bitting depth' of those ridges: basically, how deeply they cut into the key shaft, or where they plateau out. If a key is inserted at a nonconstant speed, the analysis can be ruined, but the software can compensate for small speed variations.

The result of all this is that SpiKey software outputs the three most likely key designs that will fit the lock used in the audio file, reducing the potential search space from 330,000 keys to just three. 'Given that the profile of the key is publicly available for commonly used [pin-tumbler lock] keys, we can 3D-print the keys for the inferred bitting codes, one of which will unlock the door,' says Ramesh." The article has a link to a 15-minute video presentation of the research and to another article on the research.

Researchers at NYU Langone Health and Facebook's artificial intelligence division have teamed up to develop an AI model that uses less data and creates images faster than traditional MRI techniques, according to a Wall Street Journal report. From a report: The goal of the project is to create a five-minute MRI as an alternative to the 20 minutes to an hour it takes for current MRI machines to scan a patient, Michael Recht, MD, told the publication. Dr. Recht is professor and chair of New York City-based NYU Langone Health's radiology department and also a co-author of the research project. The combination of AI and MRI technology aims to construct images with less data rather than diagnose a medical condition. The project uses different technology and standards than those used to create AI-generated or synthetic media. Because it centers on constructing MRI scans, Facebook said the project must create images "that are accurate to the ground truth," compared to synthetic media, which usually needs to create a believable image, according to the report.

For the experiment, researchers created 108 patient images using standard MRI techniques as well as a second set of images in which some of the image data was thrown out. Facebook's AI model was then applied to construct the images with less data. Researchers used commercially available MRI machines, and data was collected from patients from various points of their bodies. Six MRI readers reviewed both sets of images, and readings were spaced out across a four-week period to ensure the readers could not recall important details from previous sets. Dr. Recht told the Journal that all six engineers concluded that the quality of the AI model-generated images was "as good [as] or better" than the conventional images. The AI system still needs regulatory approval, but NYU Langone is now using it to treat patients as part of an institutional review board study, according to the report.

Secure Thoughts reports that artificial intelligence company Cense AI, which specializes in "SaaS-based intelligent process automation management solutions," has leaked nearly 2.6 million medical records on the internet. PCMag reports: [O]n July 7 security researcher Jeremiah Fowler discovered two folders of medical records available for anyone to access on the internet. The data was labeled as "staging data." Fowler believes the data was made public because Cense AI was temporarily hosting it online before loading it into the company's management system or an AI bot.

The medical records are quite detailed and include names, insurance records, medical diagnosis notes, and payment records. It looks as though the data was sourced from insurance companies and relates to car accident claims and referrals for neck and spine injuries. The majority of the personal information is thought to be for individuals located in New York, with a total of 2,594,261 records exposed. Fowler sent a responsible disclosure notice to Cense AI and public access to the folders was restricted soon after. However, the damage has potentially already been done if others had previously discovered the data was available. Fowler points out that medical data is the most valuable on the black market, fetching as much as $250 per record. If someone willing to act maliciously came across this data you can guarantee it is, or has been sold.

Nations that hoard possible COVID-19 vaccines while excluding others will deepen the pandemic, World Health Organization (WHO) chief Tedros Adhanom Ghebreyesus said on Tuesday, issuing a last-ditch call for countries to join a global vaccine pact. From a report: The WHO has an Aug. 31 deadline for wealthier nations to join the "COVAX Global Vaccines Facility" for sharing vaccine hopefuls with developing countries. Tedros said he sent a letter to the WHO's 194 member states, urging participation. The global health agency also raised concerns that the pandemic's spread was being driven now by younger people, many of whom were unaware they were infected, posing a danger to vulnerable groups. Tedros' push for nations to join COVAX comes as the European Union, Britain, Switzerland and the United States strike deals with companies testing prospective vaccines. Russia and China are also working on vaccines, and the WHO fears national interests could impede global efforts.

Haider Warraich, a cardiologist, writing for the New York Times: An intriguing new study from Germany offers a glimpse into how SARS-CoV-2 affects the heart. Researchers studied 100 individuals, with a median age of just 49, who had recovered from Covid-19. Most were asymptomatic or had mild symptoms. An average of two months after they received the diagnosis, the researchers performed M.R.I. scans of their hearts and made some alarming discoveries: Nearly 80 percent had persistent abnormalities and 60 percent had evidence of myocarditis. The degree of myocarditis was not explained by the severity of the initial illness.

Though the study has some flaws, and the generalizability and significance of its findings not fully known, it makes clear that in young patients who had seemingly overcome SARS-CoV-2 it's fairly common for the heart to be affected. We may be seeing only the beginning of the damage. Researchers are still figuring out how SARS-CoV-2 causes myocarditis -- whether it's through the virus directly injuring the heart or whether it's from the virulent immune reaction that it stimulates. It's possible that part of the success of immunosuppressant medications such as the steroid dexamethasone in treating sick Covid-19 patients comes from their preventing inflammatory damage to the heart. Such steroids are commonly used to treat cases of myocarditis. Despite treatment, more severe forms of Covid-19-associated myocarditis can lead to permanent damage of the heart -- which, in turn, can lead to heart failure.

sciencehabit shares a report from Science Magazine: Nearly 60 years ago, the Nobel prize-winning physicist Eugene Wigner captured one of the many oddities of quantum mechanics in a thought experiment. He imagined a friend of his, sealed in a lab, measuring a particle such as an atom while Wigner stood outside. Quantum mechanics famously allows particles to occupy many locations at once -- a so-called superposition -- but the friend's observation "collapses" the particle to just one spot. Yet for Wigner, the superposition remains: The collapse occurs only when he makes a measurement sometime later. Worse, Wigner also sees the friend in a superposition. Their experiences directly conflict. Now, researchers in Australia and Taiwan offer perhaps the sharpest demonstration that Wigner's paradox is real. In a study published this week in Nature Physics, they transform the thought experiment into a mathematical theorem that confirms the irreconcilable contradiction at the heart of the scenario. The team also tests the theorem with an experiment, using photons as proxies for the humans. Whereas Wigner believed resolving the paradox requires quantum mechanics to break down for large systems such as human observers, some of the new study's authors believe something just as fundamental is on thin ice: objectivity. It could mean there is no such thing as an absolute fact, one that is as true for me as it is for you.

Tim Harford, writing for Financial Times (not paywalled): Last spring, I returned from the holiday of a lifetime in Japan, and reflected on the richness of the memories it had generated. Time flew by while I was there, but in hindsight 10 days somewhere vividly new had produced more memories than 10 weeks back home. I likened the effect to the compression of a film. Instead of storing each frame separately, video compression algorithms will start with the first frame of a scene and then store a series of "diffs" -- changes from one frame to the next. A slow, contemplative movie with long scenes and fixed cameras can be compressed more than a fast-moving action flick. Similarly, a week full of new experiences will seem longer in retrospect. A month of repeating the same routine might seem endless, but will be barely a blip in the memory: the "diffs" are not significant enough for the brain to bother with. After months of working from home, I now realise that there was something incomplete about this account. New experiences are indeed important for planting a rich crop of memories. But, by itself, that is not enough. A new physical space seems to be important if our brains are to pay attention.

The Covid-19 lockdown, after all, was full of new experiences. Some were grim: I lost a friend to the disease; I smashed my face up in an accident; we had to wear masks and avoid physical contact and worry about where the next roll of toilet paper was coming from. Some were more positive: the discovery of new pleasures, the honing of new skills, the overcoming of new challenges. But I doubt I am alone in finding that my memory of the lockdown months is rather thin. No matter how many new people or old friends you talk to on Zoom or Skype, they all start to smear together because the physical context is monotonous: the conversations take place while one sits in the same chair, in the same room, staring at the same computer screen.>

Time magazine reports on is a big scientific advance: "the understanding that our bodies often operate according to different clocks." Although the federal government recommends that Americans sleep seven or more hours per night for optimal health and functioning, new research is challenging the assumption that sleep is a one-size-fits-all phenomenon. Scientists have found that our internal body clocks vary so greatly that they could form the next frontiers of personalized medicine...

Human sleep is largely a mystery. We know it's important; getting too little is linked to heightened risk for metabolic disorders, Type 2 diabetes, psychiatric disorders, autoimmune disease, neurodegeneration and many types of cancer. "It's probably true that bad sleep leads to increased risks of virtually every disorder," says Dr. Louis Ptacek, a neurology professor at the University of California, San Francisco... The ideal sleep duration has long been thought to be universal. "There are many people who think everyone needs eight to eight and a half hours of sleep per night and there will be health consequences if they don't get it," says Ptacek. "But that's as crazy as saying everybody has to be 5 ft. 10 in. tall. It's just not true..."

About a decade ago, Ptacek's wife Ying-Hui Fu discovered the first human gene linked to natural short sleep; people who had a rare genetic mutation seemed to get the same benefits from six hours of sleep a night as those without the mutation got from eight hours. In 2019, Fu and Ptacek discovered two more genes connected to natural short sleep, and they'll soon submit a paper describing a fourth, providing even more evidence that functioning well on less sleep is a genetic trait...

Doctors once dismissed short sleepers as depressed or suffering from insomnia. Yet short sleepers may actually have an edge over everyone else. Research is still early, but Fu has found that besides being more efficient at sleep, they tend to be more energetic and optimistic and have a higher tolerance for pain than people who need to spend more time in bed. They also tend to live longer.

"The moon is drifting away," reports the New York Times. Every year, it gets about an inch and a half farther from us. Hundreds of millions of years from now, our companion in the sky will be distant enough that there will be no more total solar eclipses.

For decades, scientists have measured the moon's retreat by firing a laser at light-reflecting panels, known as retroreflectors, that were left on the lunar surface, and then timing the light's round trip. But the moon's five retroreflectors are old, and they're now much less efficient at flinging back light. To determine whether a layer of moon dust might be the culprit, researchers devised an audacious plan: They bounced laser light off a much smaller but newer retroreflector mounted aboard a NASA spacecraft that was skimming over the moon's surface at thousands of miles per hour. And it worked...

Dust can be kicked up by meteorites striking the moon's surface. It coated the astronauts' moon suits during their visits, and it is expected to be a significant problem if humans ever colonize the moon. While it has been nearly 50 years since a retroreflector was placed on the moon's surface, a NASA spacecraft launched in 2009 carries a retroreflector roughly the size of a paperback book. That spacecraft, the Lunar Reconnaissance Orbiter, circles the moon once every two hours, and it has beamed home millions of high-resolution images of the lunar surface...

In 2017, Dr. Erwan Mazarico, a planetary scientist at NASA Goddard Space Flight Center and his collaborators began firing an infrared laser from a station near Grasse, France — about a half-hour drive from Cannes — toward the orbiter's retroreflector. At roughly 3 a.m. on Sept. 4, 2018, they recorded their first success: a detection of 25 photons that made the round trip... After accounting for the smaller size of the orbiter's retroreflector, Dr. Mazarico and his colleagues found that it often returned photons more efficiently than the Apollo retroreflectors... "For me, the dusty reflector idea is more supported than refuted by these results" he said.
Laser-reflection measurements over long periods of time and across several reflectors "have revealed that the Moon has a fluid core," NASA notes. "Scientists can tell by monitoring the slightest wobbles as the Moon rotates."