By Will Dunham
WASHINGTON – An immense crater in northwestern Greenland, buried under a thick sheet of ice and first spotted in 2015, is much older than previously suspected – formed by a meteorite impact 58 million years ago, rather than 13,000 years ago as had been proposed.
Scientists said on Wednesday they used two different dating methods on sand and rock left over from the impact to determine when the crater – about 19 miles (31 km) wide – was formed. They found that the meteorite – roughly one to 1.25 miles (1.5-2 km) in diameter – struck Greenland about 8 million years after a larger asteroid impact at Mexico’s Yucatan Peninsula wiped out the dinosaurs.
The crater lies beneath Greenland’s Hiawatha Glacier, covered by an ice sheet six tenths of a mile (1 km) deep. It had remained undetected until airborne ice-penetrating radar data tipped off scientists about its existence.
It is one of Earth’s 25 largest-known impact craters. Over the eons, Earth has been hit by space rocks innumerable times, though gradual changes in the planet’s surface have erased or obscured many of the craters.
Greenland at the time – during the Paleocene Epoch – was not the icy place it is today, and instead was covered with temperate rain forests populated by a variety of trees and inhabited by some of the mammals that became Earth’s dominant land animals after the dinosaurs – aside from their bird descendants – went extinct.
The meteorite released millions of times more energy than an atomic bomb, leaving a crater big enough to swallow the city of Washington.
“The impact would have devastated the local region,” said Swedish Museum of Natural History geologist Gavin Kenny, lead author of the research published in the journal Science Advances http://www.science.org/doi/10.1126/sciadv.abm2434.
“The air blast from the impact would have knocked down most trees within tens to hundreds of kilometers, and the thermal blast from the impact would have ignited trees up to hundreds of kilometers from the site of impact, starting enormous forest fires,” Kenny added.
The impact also would have triggered regional seismic shaking while ash from the forest fires and dust and molten rock that had been violently ejected into the atmosphere would have rained down, yielding a thick blanket of debris, Kenny said.
As bad as it was, it did not approach the scale of calamity wrought by the asteroid – estimated at 7.5 miles (12 km) wide – that struck 66 million years ago, erasing three quarters of Earth’s species and initiating a global climate catastrophe.
“Whether the impact had a long-lasting effect on the global climate is currently unclear, but unlikely in my opinion,” said geology professor and study co-author Michael Storey of the Natural History Museum of Denmark.
Some scientists had hypothesized that the impact occurred after the Greenland Ice Sheet formed 2.6 million years ago and perhaps even as recently as about 13,000 years ago to initiate a documented cold period.
The researchers used two dating methods based on radioactive decay – the transformation of atoms of one element into atoms of another element. Because the ice-encased crater is inaccessible, they tested sand from rocks superheated by the impact and minerals called shocked zircons contained in pebbles – all scooped up from a river carrying material from the crater out of the glacier. Both methods yielded the same age results.
“Thus, the impact did not happen – or cause a climate-change event – in the time of humans as had been proposed and speculated previously,” Kenny said.
“Impacts of this size occur only every few million years so we don’t need to be very worried about such an impact happening anytime soon,” Kenny added.
A good day to die: doom for the dinosaurs came in springtime
Scientists count the world’s tree species (spoiler: it’s a bunch)
Older date for Ethiopian fossils sheds light on rise of Homo sapiens
NASA's InSight still hunting marsquakes as power levels diminish – Phys.org
Dusty solar panels and darker skies are expected to bring the Mars lander mission to a close around the end of this year.
NASA’s InSight Mars lander is gradually losing power and is anticipated to end science operations later this summer. By December, InSight’s team expects the lander to have become inoperative, concluding a mission that has thus far detected more than 1,300 marsquakes—most recently, a magnitude 5 that occurred on May 4—and located quake-prone regions of the Red Planet.
The information gathered from those quakes has allowed scientists to measure the depth and composition of Mars’ crust, mantle, and core. Additionally, InSight (short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) has recorded invaluable weather data and studied remnants of Mars’ ancient magnetic field.
“InSight has transformed our understanding of the interiors of rocky planets and set the stage for future missions,” said Lori Glaze, director of NASA’s Planetary Science Division. “We can apply what we’ve learned about Mars’ inner structure to Earth, the Moon, Venus, and even rocky planets in other solar systems.”
InSight landed on Mars Nov. 26, 2018. Equipped with a pair of solar panels that each measures about 7 feet (2.2 meters) wide, it was designed to accomplish the mission’s primary science goals in its first Mars year (nearly two Earth years). Having achieved them, the spacecraft is now into an extended mission, and its solar panels have been producing less power as they continue to accumulate dust.
Because of the reduced power, the team will soon put the lander’s robotic arm in its resting position (called the “retirement pose”) for the last time later this month. Originally intended to deploy the seismometer and the lander’s heat probe, the arm has played an unexpected role in the mission: Along with using it to help bury the heat probe after sticky Martian soil presented the probe with challenges, the team used the arm in an innovative way to remove dust from the solar panels. As a result, the seismometer was able to operate more often than it would have otherwise, leading to new discoveries.
When InSight landed, the solar panels produced around 5,000 watt-hours each Martian day, or sol—enough to power an electric oven for an hour and 40 minutes. Now, they’re producing roughly 500 watt-hours per sol—enough to power the same electric oven for just 10 minutes.
Additionally, seasonal changes are beginning in Elysium Planitia, InSight’s location on Mars. Over the next few months, there will be more dust in the air, reducing sunlight—and the lander’s energy. While past efforts removed some dust, the mission would need a more powerful dust-cleaning event, such as a “dust devil” (a passing whirlwind), to reverse the current trend.
“We’ve been hoping for a dust cleaning like we saw happen several times to the Spirit and Opportunity rovers,” said Bruce Banerdt, InSight’s principal investigator at NASA’s Jet Propulsion Laboratory in Southern California, which leads the mission. “That’s still possible, but energy is low enough that our focus is making the most of the science we can still collect.”
If just 25% of InSight’s panels were swept clean by the wind, the lander would gain about 1,000 watt-hours per sol—enough to continue collecting science. However, at the current rate power is declining, InSight’s non-seismic instruments will rarely be turned on after the end of May.
Energy is being prioritized for the lander’s seismometer, which will operate at select times of day, such as at night, when winds are low and marsquakes are easier for the seismometer to “hear.” The seismometer itself is expected to be off by the end of summer, concluding the science phase of the mission.
At that point, the lander will still have enough power to operate, taking the occasional picture and communicating with Earth. But the team expects that around December, power will be low enough that one day InSight will simply stop responding.
Jet Propulsion Laboratory
NASA’s InSight still hunting marsquakes as power levels diminish (2022, May 17)
retrieved 18 May 2022
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
Peek-a-Boo Moon: Astronaut on Space Station Captures Spectacular Photos of the Lunar Eclipse – SciTechDaily
On the evening of May 15, 2022, Earth passed between the Sun and the Moon blocking sunlight and casting a shadow on the lunar surface. ESA astronaut Samantha Cristoforetti witnessed this lunar eclipse from the International Space Station and captured it in a series of photographs.
During a lunar eclipse, Earth’s atmosphere scatters sunlight. The blue light from the Sun scatters away, and longer-wavelength red, orange, and yellow light pass through, turning our Moon red.
In these images, the Moon appears to play hide and seek with one of the International Space Station’s solar panels:
Samantha is living and working aboard the Space Station for her second mission, ‘Minerva’. Learn more about Samantha and the Minerva mission.
African scientists and technology could drive future black hole discoveries – The Conversation Africa
Astronomers have revealed the first image of the black hole at the centre of our galaxy, the Milky Way. The image was produced by the Event Horizon Telescope (EHT) Collaboration, an international team made up of over 300 scientists on five continents – including Africa.
Black holes were predicted by Albert Einstein’s General Theory of Relativity over a century ago. They are regions of space so dense that nothing, including light, can escape. Their boundary is known as the event horizon, which marks the point of no return. That’s just one of the reasons these objects are hidden from our eyes. The other is that they are exceedingly small, when placed in their cosmic context. If our Milky Way galaxy were the size of a soccer field, its black hole event horizon would be a million times smaller than a pin prick at centrefield.
How, then, can one photograph them? Our team did so by capturing light from the hot swirling gas in the immediate vicinity of the black hole. This light, with a wavelength of 1 millimetre, is recorded by a global network of antennas that form a single, Earth-sized virtual telescope.
The light looks rather like a ring, a characteristic signature that is the direct consequence of two key processes. First, the black hole is so dense that it bends the path of light near it. Second, it captures light that strays too close to the event horizon. The combined effect produces a so-called black hole shadow – a brightened ring surrounding a distinct deficit of light centred on the black hole. In the case of our Milky Way black hole, this ring has the apparent size of a doughnut on the moon, requiring an extraordinary engineering effort to bring it into focus.
The unveiling of an image of our black hole, Sagittarius A*, is not just a massive moment for science. It could also be an important catalyst for diversifying African astrophysics research using existing strengths. We were the only two of more than 300 EHT team members based on the African continent. The continent doesn’t host any EHT telescopes – we were brought on board because of expertise we’ve developed in preparation for the world’s largest radio telescope, the Square Kilometre Array (SKA), to be co-hosted by South Africa and Australia.
Why the image is important
This is not the first time a black hole image has captured people’s attention. We were also members of the team that captured the first ever image of a black hole in 2019 (this one is at the centre of a different galaxy, Messier 87, which is 55 million light years away). It has been estimated that more than 4.5 billion people saw that image. Sagittarius A* has also dominated headlines and captured people’s imaginations.
But there’s more to this result than just an incredible image. A plethora of rich scientific results has been described in ten publications by the team. Here are three of our primary highlights.
First, the image is a remarkable validation of Einstein’s General Theory of Relativity. The EHT has now imaged two black holes with masses that differ by a factor of over 1000. Despite the dramatic difference in mass, the measured size and shape are consistent with theoretical predictions.
Second, we have now imaged black holes with very different environments. A wealth of prior research over the past two or three decades shows strong empirical evidence that galaxies and their black holes co-evolve over cosmic time, despite their completely disparate sizes. By zooming into the event horizon of black holes in giant galaxies like M87, as well as more typical galaxies like our own Milky Way, we learn more about how this seemingly implausible relationship between the black hole and its host galaxy plays out.
Third, the image provides us with new insights on the central black hole in our own galactic home. It is the nearest such beast to Earth, so it provides a unique laboratory to understand this interplay – not unlike scrutinising a tree in your own garden to better understand the forests on the distant horizon.
Southern Africa’s geographic advantage
We are proud to be part of the team that produced the first black hole images. In future, we believe South Africa, and the African continent more broadly (including a joint Dutch-Namibian initiative), could play a critical role in making the first black hole movies.
As has been the case with the country’s key role in paleoanthropology, there are contributions to global astronomy that can only be made from South African soil. Sagittarius A* lies in the southern sky, passing directly above South Africa. That is a major reason why this image of the Milky Way’s centre, taken by the MeerKAT (a precursor to the SKA) is the best there is.
South Africa also has well-established infrastructure at its astronomical sites, which are protected by legislation. And it has world-class engineers at the forefront of their craft. This makes for low-cost, high-performance telescopes delivered on time and to budget.
New technology is also on our side: a cutting-edge simultaneous multi-frequency receiver design, pioneered by our Korean colleagues, means that EHT sites no longer need to be the most pristine, high-altitude locations on Earth.
All the elements are in place for a dramatic increase in the number of young Africans who participate in this new era of black hole imaging and precision tests of gravity. In the coming years, we hope to be writing about findings that couldn’t have been made without technology on South African soil, as well as African scientists leading high-impact, high-visibility EHT science in synergy with our multi-wavelength astronomy and high-energy astrophysics programmes.
Poilievre personally holds investment in Bitcoin as he promotes crypto to Canadians – CTV News
Early signs point to a slight cooling of Grey-Bruce real estate market – Owen Sound Sun Times
Why You Can’t Just Order Baby Formula From Canada – Lifehacker
Silver investment demand jumped 12% in 2019
Europe kicks off vaccination programs | All media content | DW | 27.12.2020 – Deutsche Welle
News3 hours ago
Ghosts of History Arise
Economy23 hours ago
Payday loans are on the rise in Canada, due to the pandemic
News23 hours ago
Trinidad and Tobago to launch the 2022 Pan African Festival
Tech7 hours ago
Apple Podcasts Update Enables Annual Subscriptions – PCMag
Business22 hours ago
Are you as a 2SLGBTQIA+ conformist being treated the same as heterosexuals at your place of work?
Tech19 hours ago
Apple Podcasts gets storage cleaning tools and annual subscriptions with iOS 15.5 – PhoneArena
Tech18 hours ago
iOS 15.5—Apple Issues Massive iPhone Security Update For Millions Of Users – Forbes
News12 hours ago
Monarchists criticize Canada's 'lacklustre' and 'embarrassing' Platinum Jubilee plans – CBC News