Month: April 2019

The Space Rock That Hit The Moon At 61,000 Kilometers An Hour

Observers watching January’s total eclipse of the Moon saw a rare event, a short-lived flash as a meteorite hit the lunar surface. Spanish astronomers now think the space rock collided with the Moon at 61,000 kilometres an hour, excavating a crater 10 to 15 metres across. Prof Jose Maria Madiedo of the University of Huelva, and Dr Jose L. Ortiz of the Institute of Astrophysics of Andalusia, publish their results in a new paper in Monthly Notices of the Royal Astronomical Society.

Total lunar eclipses take place when the Moon moves completely into the shadow of the Earth. The Moon takes on a red colour — the result of scattered sunlight refracted through the Earth’s atmosphere — but is much darker than normal. These spectacular events are regularly observed by astronomers and the wider public alike.

The most recent lunar eclipse took place on 21 January 2019, with observers in North and South America and Western Europe enjoying the best view. At 0441 GMT, just after the total phase of the eclipse began, a flash was seen on the lunar surface. Widespread reports from amateur astronomers indicated the flash — attributed to a meteorite impact — was bright enough to be seen with the naked eye.

Madiedo and Ortiz operate the Moon Impacts Detection and Analysis System (MIDAS), using eight telescopes in south of Spain to monitor the lunar surface. The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts.

“Something inside of me told me that this time would be the time,” said Madiedo, who was impressed when he observed the event, as it was brighter than most of the events regularly detected by the survey.

Unlike the Earth, the Moon has no atmosphere to protect it and so even small rocks can hit its surface. Since these impacts take place at huge speeds, the rocks are instantaneously vaporised at the impact site, producing an expanding plume of debris whose glow can be detected from our planet as short-duration flashes.

MIDAS telescopes observed the impact flash at multiple wavelengths (different colours of light), improving the analysis of the event. Madiedo and Ortiz conclude that the incoming rock had a mass of 45kg, measured 30 to 60 centimetres across, and hit the surface at 61,000 kilometres an hour. The impact site is close to the crater Lagrange H, near the west-south-west portion of the lunar limb.

The two scientists assess the impact energy as equivalent to 1.5 tonnes of TNT, enough to create a crater up to 15 metres across, or about the size of two double decker buses side by side. The debris ejected is estimated to have reached a peak temperature of 5400 degrees Celsius, roughly the same as the surface of the Sun.

Madiedo comments: “It would be impossible to reproduce these high-speed collisions in a lab on Earth. Observing flashes is a great way to test our ideas on exactly what happens when a meteorite collides with the Moon.”

The team plan to continue monitoring meteorite impacts on the lunar surface, not least to understand the risk they present to astronauts, set to return to the Moon in the next decade.

Magma Is The Key To The Moon’s Makeup

For more than a century, scientists have squabbled over how Earth’s moon formed. But researchers at Yale and in Japan say they may have the answer.

Many theorists believe a Mars-sized object slammed into the early Earth, and material dislodged from that collision formed the basis of the moon. When this idea was tested in computer simulations, it turned out that the moon would be made primarily from the impacting object. Yet the opposite is true; we know from analyzing rocks brought back from Apollo missions that the moon consists mainly of material from Earth.

A new study published April 29 in Nature Geoscience, co-authored by Yale geophysicist Shun-ichiro Karato, offers an explanation.

The key, Karato says, is that the early, proto-Earth — about 50 million years after the formation of the Sun — was covered by a sea of hot magma, while the impacting object was likely made of solid material. Karato and his collaborators set out to test a new model, based on the collision of a proto-Earth covered with an ocean of magma and a solid impacting object.

The model showed that after the collision, the magma is heated much more than solids from the impacting object. The magma then expands in volume and goes into orbit to form the moon, the researchers say. This explains why there is much more Earth material in the moon’s makeup. Previous models did not account for the different degree of heating between the proto-Earth silicate and the impactor.

“In our model, about 80% of the moon is made of proto-Earth materials,” said Karato, who has conducted extensive research on the chemical properties of proto-Earth magma. “In most of the previous models, about 80% of the moon is made of the impactor. This is a big difference.”

Karato said the new model confirms previous theories about how the moon formed, without the need to propose unconventional collision conditions — something theorists have had to do until now.

For the study, Karato led the research into the compression of molten silicate. A group from the Tokyo Institute of Technology and the RIKEN Center for Computational Science developed a computational model to predict how material from the collision became the moon.

The first author of the study is Natsuki Hosono of RIKEN. Additional co-authors are Junichiro Makino and Takayuki Saitoh.

New Fallout From ‘The Collision That Changed The World’

When the landmass that is now the Indian subcontinent slammed into Asia about 50 million years ago, the collision changed the configuration of the continents, the landscape, global climate and more. Now a team of Princeton University scientists has identified one more effect: the oxygen in the world’s oceans increased, altering the conditions for life.

“These results are different from anything people have previously seen,” said Emma Kast, a graduate student in geosciences and the lead author on a paper coming out in Science on April 26. “The magnitude of the reconstructed change took us by surprise.”

Kast used microscopic seashells to create a record of ocean nitrogen over a period from 70 million years ago — shortly before the extinction of the dinosaurs — until 30 million years ago. This record is an enormous contribution to the field of global climate studies, said John Higgins, an associate professor of geosciences at Princeton and a co-author on the paper.

“In our field, there are records that you look at as fundamental, that need to be explained by any sort of hypothesis that wants to make biogeochemical connections,” Higgins said. “Those are few and far between, in part because it’s very hard to create records that go far back in time. Fifty-million-year-old rocks don’t willingly give up their secrets. I would certainly consider Emma’s record to be one of those fundamental records. From now on, people who want to engage with how the Earth has changed over the last 70 million years will have to engage with Emma’s data.”

In addition to being the most abundant gas in the atmosphere, nitrogen is key to all life on Earth. “I study nitrogen so that I can study the global environment,” said Daniel Sigman, Princeton’s Dusenbury Professor of Geological and Geophysical Sciences and the senior author on the paper. Sigman initiated this project with Higgins and then-Princeton postdoctoral researcher Daniel Stolper, who is now an assistant professor of Earth and planetary science at the University of California-Berkeley.

Every organism on Earth requires “fixed” nitrogen — sometimes called “biologically available nitrogen.” Nitrogen makes up 78% of our planet’s atmosphere, but few organisms can “fix” it by converting the gas into a biologically useful form. In the oceans, cyanobacteria in surface waters fix nitrogen for all other ocean life. As the cyanobacteria and other creatures die and sink downward, they decompose.

Nitrogen has two stable isotopes, 15N and 14N. In oxygen-poor waters, decomposition uses up “fixed” nitrogen. This occurs with a slight preference for the lighter nitrogen isotope, 14N, so the ocean’s 15N-to-14N ratio reflects its oxygen levels.

That ratio is incorporated into tiny sea creatures called foraminifera during their lives, and then preserved in their shells when they die. By analyzing their fossils — collected by the Ocean Drilling Program from the North Atlantic, North Pacific, and South Atlantic — Kast and her colleagues were able to reconstruct the 15N-to-14N ratio of the ancient ocean, and therefore identify past changes in oxygen levels.

Oxygen controls the distribution of marine organisms, with oxygen-poor waters being bad for most ocean life. Many past climate warming events caused decreases in ocean oxygen that limited the habitats of sea creatures, from microscopic plankton to the fish and whales that feed on them. Scientists trying to predict the impact of current and future global warming have warned that low levels of ocean oxygen could decimate marine ecosystems, including important fish populations.

When the researchers assembled their unprecedented geologic record of ocean nitrogen, they found that in the 10 million years after dinosaurs went extinct, the 15N-to-14N ratio was high, suggesting that ocean oxygen levels were low. They first thought that the warm climate of the time was responsible, as oxygen is less soluble in warmer water. But the timing told another story: the change to higher ocean oxygen occurred around 55 million years ago, during a time of continuously warm climate.

“Contrary to our first expectations, global climate was not the primary cause of this change in ocean oxygen and nitrogen cycling,” Kast said. The more likely culprit? Plate tectonics. The collision of India with Asia — dubbed “the collision that changed the world” by legendary geoscientist Wally Broecker, a founder of modern climate research — closed off an ancient sea called the Tethys, disturbing the continental shelves and their connections with the open ocean.

“Over millions of years, tectonic changes have the potential to have massive effects on ocean circulation,” said Sigman. But that doesn’t mean climate change can be discounted, he added. “On timescales of years to millenia, climate has the upper hand.”

Spinning Black Hole Sprays Light-Speed Plasma Clouds Into Space

Astronomers have discovered rapidly swinging jets coming from a black hole almost 8000 light-years from Earth.

Published today in the journal Nature, the research shows jets from V404 Cygni’s black hole behaving in a way never seen before on such short timescales.

The jets appear to be rapidly rotating with high-speed clouds of plasma — potentially just minutes apart — shooting out of the black hole in different directions.

Lead author Associate Professor James Miller-Jones, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said black holes are some of the most extreme objects in the Universe.

“This is one of the most extraordinary black hole systems I’ve ever come across,” Associate Professor Miller-Jones said.

“Like many black holes, it’s feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity.

“What’s different in V404 Cygni is that we think the disk of material and the black hole are misaligned. “This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation.”

V404 Cygni was first identified as a black hole in 1989 when it released a big outburst of jets and radiation.

Astronomers looking at archival photographic plates then found previous outbursts in observations from 1938 and 1956.

Associate Professor Miller-Jones said that when V404 Cygni experienced another very bright outburst in 2015, lasting for two weeks, telescopes around the world tuned in to study what was going on.

“Everybody jumped on the outburst with whatever telescopes they could throw at it,” he said.

“So we have this amazing observational coverage.”

When Associate Professor Miller-Jones and his team studied the black hole, they saw its jets behaving in a way never seen before.

Where jets are usually thought to shoot straight out from the poles of black holes, these jets were shooting out in different directions at different times.

And they were changing direction very quickly — over no more than a couple of hours.

Associate Professor Miller-Jones said the change in the movement of the jets was because of the accretion disk — the rotating disk of matter around a black hole.

He said V404 Cygni’s accretion disk is 10 million kilometres wide, and the inner few thousand kilometres was puffed up and wobbling during the bright outburst.

“The inner part of the accretion disk was precessing and effectively pulling the jets around with it,” Associate Professor Miller-Jones said.

“You can think of it like the wobble of a spinning top as it slows down — only in this case, the wobble is caused by Einstein’s theory of general relativity.”

The research used observations from the Very Long Baseline Array, a continent-sized radio telescope made up of 10 dishes across the United States, from the Virgin Islands in the Caribbean to Hawaii.

Co-author Alex Tetarenko — a recent PhD graduate from the University of Alberta and currently an East Asian Observatory Fellow working in Hawaii — said the speed the jets were changing direction meant the scientists had to use a very different approach to most radio observations.

“Typically, radio telescopes produce a single image from several hours of observation,” she said.

“But these jets were changing so fast that in a four-hour image we just saw a blur.

“It was like trying to take a picture of a waterfall with a one-second shutter speed.” Instead, the researchers produced 103 individual images, each about 70 seconds long, and joined them together into a movie.

“It was only by doing this that we were able to see these changes over a very short time period,” Dr Tetarenko said.

Study co-author Dr Gemma Anderson, who is also based at ICRAR’s Curtin University node, said the wobble of the inner accretion disk could happen in other extreme events in the Universe too.

“Anytime you get a misalignment between the spin of a black hole and the material falling in, you would expect to see this when a black hole starts feeding very rapidly,” Dr Anderson said.

“That could include a whole bunch of other bright, explosive events in the Universe, such as supermassive black holes feeding very quickly or tidal disruption events, when a black hole shreds a star.”

Giant Planets And Big Data: What Deep Learning Reveals About Saturn’s Storms

A “deep learning” approach to detecting storms on Saturn is set to transform our understanding of planetary atmospheres, according to University College London and University of Arizona researchers.

The new technique, called PlanetNet, identifies and maps the components and features in turbulent regions of Saturn’s atmosphere, giving insights into the processes that drive them.

A study, published today in Nature Astronomy, provides results from the first demonstration of the PlanetNet algorithm. The results clearly show the vast regions affected by storms and that dark storm clouds contain material swept up from the lower atmosphere by strong vertical winds.

Developed by UA and UCL researchers, PlanetNet was trained and tested using infrared data from the Visible and Infrared Mapping Spectrometer instrument on Cassini, a joint mission between NASA, the European Space Agency and the Italian Space Agency.

A dataset containing multiple, adjacent storms observed at Saturn in February 2008 was chosen to provide a range of complex atmospheric features to challenge PlanetNet’s capabilities.

“PlanetNet enables us to analyze much bigger volumes of data, and this gives insights into the large-scale dynamics of Saturn,” said UA professor Caitlin Griffith, who co-authored the paper. “The results reveal atmospheric features that were previously undetected. PlanetNet can easily be adapted to other datasets and planets, making it an invaluable potential tool for many future missions.”

Previous analysis of the dataset indicated a rare detection of ammonia in Saturn’s atmosphere, in the form of an S-shaped cloud.

The map produced through PlanetNet shows that this feature is a prominent part of a much larger upwelling of ammonia ice clouds around a central dark storm. PlanetNet identifies similar upwelling around another small storm, suggesting such features are quite common.

The map also shows pronounced differences between the center of storms and the surrounding areas, indicating that the eye gives a clear view into the warmer, deep atmosphere.

“Missions like Cassini gather enormous amounts of data, but classical techniques for analysis have drawbacks, either in the accuracy of information that can be extracted or in the time they take to perform. Deep learning enables pattern recognition across diverse, multiple data sets,” said Ingo Waldmann, lead author and deputy director of the UCL Centre for Space and Exoplanet Data.

“This gives us the potential to analyze atmospheric phenomena over large areas and from different viewing angles, and to make new associations between the shape of features and the chemical and physical properties that create them,” he said.

Initially, PlanetNet searches the data for signs of clustering in the cloud structure and gas composition. For areas of interest, it trims the data to remove uncertainties at the edges and runs a parallel analysis of the spectral and spatial properties. Recombining the two data streams, PlanetNet creates a map that presents quickly and accurately the major components of Saturn’s storms with unprecedented precision.

PlanetNet’s accuracy has been validated on Cassini data not included in the training phase. The whole dataset has also been rotated and resampled to create synthetic data for further testing. PlanetNet has achieved over 90 percent classification accuracy in both test cases.

The project received funding from the European Research Council and the Science and Technology Funding Council.

India: Heat Wave Continues As Fani Threatens Eastern Areas With Flooding, Damaging Wind

Residents along India’s eastern coast are being warned about potential impacts from Cyclonic Storm Fani this week, while no relief will come from the dangerous heat in the nation’s northern and western regions.

Fani strengthened into a cyclonic storm on Saturday, local time. The strength of a cyclonic storm equates to a tropical storm in the Atlantic or northern Pacific basins.

Further strengthening can cause the system to intensify into the equivalent of a hurricane and be called a severe cyclonic storm or a very severe cyclonic storm by Tuesday with further strengthening expected later this week.

Seas will build and become dangerous for boaters and swimmers around the southern Bay of Bengal as the storm intensifies.

Residents along the eastern coast of India are being alerted to potential other hazards.

“The main threats from this storm will be heavy rain, flooding and damaging wind gusts,” AccuWeather Senior Meteorologist Jason Nicholls said, “but the exact amount of rain and strength of the winds will be dependent on how close it tracks to the coast.”

Latest indications spare Sri Lanka and Tamil Nadu in India from the brunt of the cyclone’s rain and wind.

Even if the storm bypasses Sri Lanka and Tamil Nadu, areas to the north may not be as fortunate.

One scenario for the storm is to threaten the coast from northern Andhra Pradesh to Odisha and West Bengal with heavy rain and wind later this week into the weekend.

Landfall as a dangerous tropical cyclone may occur in this scenario putting millions of people at risk for damaging winds, inundating storm surge, and flooding rainfall. Locations from Visakhapatnam northward to the border with Bangladesh are at risk for landfall at this time.

Beyond West Bengal, flooding rain and strong winds may accompany the storm as it slams into Bangladesh with an eventual track into northeastern India later in the weekend or early next week.

A second scenario would keep the worst impacts from Fani offshore from India as the storm tracks northward across the Bay of Bengal this week.

Coastal locations may see brief downpours and gusty winds; however, damaging winds and widespread flooding would not be expected.

A direct hit on Bangladesh or northern Myanmar would be possible in this scenario bringing life-threatening impacts to the region from this weekend into early next week.

Download the free AccuWeather app to remain aware of the latest projected path of the cyclone and any threats for your community.

Regardless of the storm’s exact track, it will not press far enough inland to bring any heat relief to northern and western India.

Thursday marked the hottest day so far this year in the National Capital Region (NCR), when temperatures soared to 43.2 C (109.8 F) at the Indira Gandhi International Airport.

Similar temperatures were felt across the city and surrounding NCR from Saturday into Monday.

Temperatures will remain dangerously high each day this week across the NCR and much of central and northern India.

“India endures lengthy heat waves each year prior to the arrival of monsoonal rainfall; however, this heat has arrived earlier than normal in recent years, putting more people at risk for heat-related illnesses,” AccuWeather Senior Meteorologist Eric Leister said.

Residents will have to continue to take the necessary precautions to avoid heat-related illnesses.

Drinking plenty of water, spending time in the shade and wearing light clothing will be necessary. When possible, strenuous outdoor activity should be avoided during the hottest part of the day.

Stagnant conditions contributing to the high heat are also resulting in dangerously poor air quality conditions. Face masks should be worn by anyone spending time outdoors. Children, the elderly and those with respiratory or cardiovascular health conditions should avoid spending time outside as much as possible.

Tropical Cyclone Kenneth Death Toll Rises To 38 In Mozambique, Officials Say

The death toll from Tropical Cyclone Kenneth has climbed to 38, the Mozambican government’s disaster management institute said on Monday.

Four people have also died in the island nation of Comoros, according to the United Nations Office for the Coordination of Humanitarian Affairs.

The cyclone, the strongest storm to hit the region since records began, made landfall in Mozambique on Thursday.

Kenneth is the second powerful tropical storm to hit southeast Africa in five weeks. Despite its power, Cyclone Kenneth is slow-moving, leading experts to fear it could continue to dump torrential rains on an area still reeling from the devastation wrought by Cyclone Idai.

That storm killed 750 people across southern Africa, forced thousands into camps in March and wreaked an estimated $1 billion worth of damage — about 10% of Mozambique’s GDP.

In the commercial hub and provincial capital of Pemba, residents Monday said they hoped the worst was over after a weekend of heavy rains and flooding since Cyclone Kenneth made landfall Thursday.

“The rain has stopped, at least for now. There is still water on the ground but the main roads in the city are now passable,” said resident Innocent Mushunje.

Kevin Record, a hotel owner on the hard-hit island of Ibo, said the region was still without power and “waiting for the cavalry to arrive.”

Forecasters said northern Mozambique could see up to 500 millimeters of rain (about 20 inches) over the next five days, which could exacerbate the flooding.

“The soil is saturated with rain and the rivers are already swollen, so the emergency is likely to get worse,” said Michel Le Pechoux, UNICEF’s deputy representative in Mozambique. “We’re doing everything we can to get teams and supplies on the ground to keep people safe.”

Save the Children said in a separate statement that the storm “has caused extensive damage, ripping homes apart and wiping out entire communities,” and is warning that current conditions have made it extremely difficult to deliver aid to those in need.

“We have grave fears for the thousands of families currently taking shelter under the wreckage of their homes. They urgently need food, water and shelter to survive the coming days,” said Nicholas Finney, Save the Children’s response team leader in Mozambique.

Finney said that the NGO tried to reach some of the hard-hit areas Sunday but were forced to turn back “because rivers had burst their banks and the roads were under water.”

“Flights and helicopters have also been grounded and this means humanitarian access is virtually impossible. We are desperately trying to look for ways to deliver emergency supplies,” said Finney.

The United Nations’ disaster response agency pledged to release $13 million to pay for food, shelter, health, water and sanitation assistance in both Comoros and Mozambique.

“The funds will help in reducing the suffering of the affected people including mitigating the impact on food security caused by the destruction and loss of farmland, livestock and fisheries, in addition to the damage and destruction of homes,” said Mark Lowcock, the UN’s emergency relief coordinator.

Mozambique’s natural disaster management said last week that nearly 3,400 homes were destroyed and more than 18,000 were displaced by Kenneth.