Latest news with #Earth
ABC News
3 hours ago
- Climate
- ABC News
Winter solstice is on Saturday but it won't bring Australia's coldest weather
This Saturday is the 2025 winter solstice, Australia's shortest day of the year. How many hours of daylight you experience depends entirely on latitude — Hobart will see only 9 hours and 1 minute while Darwin will see 11 hours and 24 minutes. For remaining capitals, running south to north: The variation in the length of day through the year, and indeed the very existence of seasons, is due to the Earth's tilt of 23.5 degrees. As we orbit the Sun, this tilt leads to changes in the length of day and the angle of the Sun viewed from the ground — it's higher in summer and lower in winter. Saturday, the winter solstice, marks the day when the Sun is furthest north, tracking directly over the Tropic of Cancer. The exact time of this year's solstice is 12:42pm for eastern states and just after midday for the NT and SA, meaning the longest night of the year will follow immediately after. For WA, a 10:42am solstice will result in Friday night being the longest of the year. From this position over the Northern Hemisphere, Australia is not only in Earth's shadow for the longest period, but critically for temperatures, it's also when the Sun's noon position is lowest in the sky. From a simple energy perspective, the winter solstice therefore has the least amount of incoming heat directly from sunlight. However, for nearly the whole of Australia, the coldest weather does not arrive when the days are shortest. For the vast majority of the country, the coldest month is July, and for some locations, the coldest day on average is not until early August, even though days are longer and the Sun's angle is higher. The cause of the temporal anomaly between the shortest day and coldest temperatures is due to the different heat capacities of substances. Put simply, land regions warm up and cool down much faster than oceans. This property is demonstrated daily as air temperatures fluctuate sharply between day and night, while water temperatures remain steady regardless of the hour. Water, therefore, is said to have a greater heat capacity than land, which leads to an annual minimum temperature for waters surrounding Australia occurring mostly between July and September — well after the Southern Hemisphere's shortest day in June. The warmer oceans earlier in winter act as one giant heater — they transfer energy into the atmosphere and delay the coldest weather until well after incoming heat from the sun reaches a minimum on June 21. This delay is called seasonal lag, and it also occurs after the summer solstice in December, with the hottest weather in southern Australia not arriving until January. The coldest weather in any given year is determined by the exact timing of weather systems; however, on average, due to seasonal lag, it occurs a few weeks after the winter solstice. The delay is greatest in regions where the climate is influenced by neighbouring oceans — so coastal areas of southern Australia have a longer temperature lag than inland regions. For maximum temperatures, the absolute peak lag is about five weeks in south-west Tasmania and on the southern WA coast near Albany. For Sydney, Melbourne, Brisbane, Perth and Adelaide the coldest day of the year — on average — lands in the second or third week of July. Unsurprisingly, parts of the central interior, well away from oceans, have a lag of only a few days. The seasonal changes in daytime temperatures across northern Australia are more intricate due to the contrast in cloud cover through the year — there are even small regions that have their average lowest winter maximums a few days before the winter solstice. The national variability in minimum temperatures is far more uniform, with well over 90 per cent of Australia, including the northern tropics, having its coldest night between July 11 and 21. Seasonal lag is even greater in some Northern Hemisphere coastal regions, depending on the time of year. San Francisco's warmest month of the year is not until September, a full three months after the summer solstice, during which time the length of day has already shortened by more than two hours. Of course, thanks to the natural variability of weather, the actual date of the coldest weather will vary considerably from year to year — even though this is far more likely to occur in winter. According to the Bureau of Meteorology, for the northern tropics, the coldest day of the year across a 30-year period can occur in most months. For most of southern and central Australia, the range is from April or May to anytime between August and November.
France 24
3 hours ago
- Business
- France 24
France becomes biggest shareholder in Eutelsat, EU rival to Musk's Starlink
The French state is set to become Eutelsat's biggest shareholder following a 1.35 billion-euro ($1.55 billion) investment that the financial ministry said will help the satellite company compete with Elon Musk 's Starlink. Debt-laden Eutelsat has garnered unprecedented attention this year from European governments seeking alternatives to reliance on US satellite companies. "The race is on. That's why we have to take a position now and invest now. Otherwise, the whole market will be occupied and France and Europe will depend on other powers in future," Macron's office told AFP. The 717 million-euro capital injection by the French state, which was part of an overall deal with other investors worth 1.35 billion euros, will make Paris Eutelsat's largest shareholder, raising its stake from 13 percent to just under 30 percent. The announcement comes as competition heats up in the satellite communications sector, where Elon Musk's Starlink is a dominant player, but some governments would prefer sovereign solutions. Eutelsat boasts more than 600 satellites since merging with British firm OneWeb in 2023, making it the world's second-largest operator of low Earth orbit (LEO) satellites, behind Starlink, and the obvious candidate as a European champion. The company has in the past called itself "the only LEO alternative to Starlink". "Eutelsat is a strategic asset contributing to European strategic autonomy," French Finance Minister Éric Lombard's office said. But it remains far smaller than the American heavyweight, which has 6,000 satellites lofted into orbit by Musk's comparatively cheap, reusable SpaceX rockets. Set to be completed by the end of this year, the capital increase is "a pivotal step in Eutelsat's strategic and financing roadmap, enabling the execution of its strategic vision", it said. The new investment will fund a renewal of Eutelsat's satellite fleet and improve its financial situation, including through a debt restructuring. Eutelsat is also gearing up to contribute to the Iris² network of European satellites in multiple orbits, supposed to offer communication services from 2030. Rush for connectivity "The war in Ukraine has shown the importance of space infrastructure for resilient communications infrastructure, whether civilian or military," Lombard's office said. "It has also spotlighted Europe's dependence on non-European technology." Musk has called Starlink the "backbone" of the Ukrainian army because of its wide use defending against Russia's invasion since 2022 – and warned that "their entire front line would collapse if I turned it off", sending Europeans scrambling for alternatives. Eutelsat had already this week signed a 10-year, billion-euro deal at the Paris Air Show to provide military communications for the French armed forces. And presenting its latest quarterly results last month, the firm said it was in active sales talks with governments both inside and outside Europe. Major shareholders stumping up money alongside Paris are shipping giant CMA CGM, Indian telecoms operator Bharti Airtel and the FSP investment fund, owned by seven French insurance companies. The two-stage plan includes a "reserved" capital increase open only to the four named investors, with a second round open to others. "Discussions are ongoing" with other investors including the British government, "which could join the capital raise in due course", Eutelsat said.
Yahoo
5 hours ago
- Science
- Yahoo
Neanderthal extinction: a space physicist reopens the debate
Neanderthals have long been the subject of intense scientific debate. This is largely because we still lack clear answers to some of the big questions about their existence and supposed disappearance. One of the latest developments is a recent study from the University of Michigan, published in the journal Science Advances. It proposes that Neanderthals went extinct for astrophysical reasons. The work was led by Agnit Mukhopadhyay, an expert in space physics, a discipline that studies natural plasmas, especially those found within our own solar system. Plasma is the state of matter that dominates the universe: the Sun and stars are huge balls of plasma, as are the northern lights. Mukhopadhyay's research suggests that a shift in the Earth's magnetic poles around 41,000 years ago, known as the Laschamp event, may have contributed to the extinction of Neanderthals. According to his work, the extreme weakening of the Earth's magnetic field during that event allowed for greater penetration of cosmic and ultraviolet radiation. This would have generated more aggressive environmental conditions that Neanderthals could not withstand, giving our own species, Homo sapiens, an edge. In this context, sapiens would have had an advantage over Neanderthals thanks to their presumed use of close-fitting clothing, ochre – a mineral with protective properties against the sun – and taking shelter in caves. Caves which, by the way, on numerous occasions were inhabited by both Neanderthals and our own species. The hypothesis is interesting, and is based on innovative three-dimensional models of the Earth's geospatial system during this period. However, as with many hypotheses that attempt to explain complex phenomena on the basis of a single variable, its scope and some of the assumptions on which it is based need to be examined more closely. One of the pillars of this hypothesis is that Neanderthals did not wear tight-fitting clothing, and would therefore have been more exposed to the harmful effects of solar radiation. It is true that sewing needles have not been definitvely linked to Neanderthals. The first needles documented in Eurasia are associated with either Denisovan or sapiens populations around 50,000 years ago, and in western Europe they did not appear until around 23,000 years ago. But this does not mean that Neanderthals did not wear clothing. In fact, the Homo sapiens who lived during episodes of extreme cold (such as the Heinrich 4 event, which occurred some 39,600 years ago) did not have sewing needles either, but they did have enough technology to make garments, and possibly tents and footwear. There is ample archaeological evidence of Neanderthals processing hides, such as the systematic use of scrapers and other tools associated with the tanning process. However, the use of fur or clothing has much older origins. In fact, the genetic study of lice has revealed that humans were already wearing clothing at least 200,000 years ago. Furthermore, in cold environments such as those they inhabited in Europe, it would have been unfeasible to survive without some form of body protection. Even if they did not have needles, it is very plausible that they used alternative systems such as ligatures or bone splinters to adapt animal hides to the body. The absence of needles should not be confused with the absence of functional clothing. The study also highlights the use of ochre by Homo sapiens, which it says offered protection against solar radiation. Although experiments have been carried out to demonstrate certain blocking capacities of ochre against ultraviolet (UV) rays, its use by human populations is not limited to a single group. In fact, evidence of pigment use during the same period has been found in Africa, the Near East and the Iberian Peninsula, and among different human lineages. The use of ochre has been documented in Neanderthal contexts for more than 100,000 years, both in Europe and in the Levant. Its application may have had multiple purposes: symbolic, therapeutic, cosmetic, healing, and even an insect repellent. There are no solid grounds for claiming that its use for protective purposes was exclusive to Homo sapiens, especially when both species shared spaces and technologies for millennia. Nor can we be sure that it was used as a protective sunscreen. Leer más: One of the most significant factors may have been the marked difference in population size. There were fewer Neanderthals, meaning they would have been assimilated by the much more numerous populations of Homo sapiens. This assimilation is reflected in the DNA of current populations, suggesting that, rather than becoming extinct, Neanderthals were absorbed into the evolutionary process. Technology also played a part– as far as we know, Neanderthals did not use hunting weapons at a distance. The invention and use of projectiles associated with hunting activities – first in stone and later in hard animal materials – appear to be an innovation specific to Homo sapiens. Their development may have given them an adaptive advantage in open environments, and a greater capacity to exploit different prey and environments. Leer más: Associating the Neanderthal 'extinction' to their supposed failure to adapt to increased solar radiation during the Laschamp excursion oversimplifies a phenomenon that remains the subject of heated debate. Put simply, the archaeological record does not support Mukhopadhyay's hypothesis. There is no evidence of an abrupt demographic collapse coinciding with this geomagnetic event, nor of a widespread catastrophic impact on other human or animal species. Moreover, if solar radiation had been such a determining factor, one would expect high mortality also among populations of sapiens that did not wear tight clothing or live in caves (in warm regions of Africa, for instance). As far as we know, this did not happen. When trying to explain the disappearance of Neanderthals, it is vital that we integrate multiple lines of archaeological, paleoanthropological and genetic evidence. These humans were not simply victims of their own technological clumsiness or of a hostile environment that they failed to cope with. They were an adaptive and culturally complex species that, for more than 300,000 years, survived multiple climatic changes – including other geomagnetic shifts such as the Blake event, which occurred about 120,000 years ago. Neanderthals developed sophisticated tools, dominated vast territories and shared many more traits with us than was assumed for decades. So did the magnetic reversal of the Earth's magnetic poles wipe out the Neanderthals? The answer is: probably not. Este artículo fue publicado originalmente en The Conversation, un sitio de noticias sin fines de lucro dedicado a compartir ideas de expertos académicos. Lee mas: Neanderthals: the oldest art in the world wasn't made by Homo sapiens Modern human DNA contains bits from all over the Neanderthal genome – except the Y chromosome. What happened? How Neanderthal language differed from modern human – they probably didn't use metaphors Las personas firmantes no son asalariadas, ni consultoras, ni poseen acciones, ni reciben financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y han declarado carecer de vínculos relevantes más allá del cargo académico citado anteriormente.
France 24
6 hours ago
- Politics
- France 24
Trump 'Golden Dome' plan tricky and expensive: experts
Trump announced plans for the space-based system last month, saying it would eventually cost around $175 billion and would be operational by the end of his term in 2029. The planned defence shield's name is a nod to Israel's Iron Dome that has intercepted thousands of short-range rockets since 2011. But the US defence system would intercept much bigger intercontinental threats. The plan comes after a 2022 Department of defence study pointed to advances by China and Russia. Beijing is closing the gap with Washington when it comes to ballistic and hypersonic missile technology, while Moscow is modernising its intercontinental-range missile systems and developing advanced precision strike missiles, it said. Trump has claimed the "Golden Dome" will be "capable of intercepting missiles even if they are launched from other sides of the world". But analysts are sceptical. "I'm not holding my breath," said Thomas Withington, an associate fellow at the RUSI defence think tank. "The challenges are so significant at this stage that they may simply be unrealistic to surround in the timeframes that the Trump administration envisages." 'Poster child for waste' Thomas Roberts, of the Georgia Institute of Technology, said the "Golden Dome" plan was based on being able to detect when a long-range missile was fired. A missile's so-called "boost phase" -- which produces a heat blast that lasts one to two minutes and can be observed from space -- is the best time to deploy defences, he said. "If you had an enormous constellation of interceptors in orbit at all times, they could be readily de-orbited -- or systematically removed from orbit -- to strike an intercontinental ballistic missile," he said. But Todd Harrison, from the American Enterprise Institute, said this would require a massive number of satellites. "It takes about 950 interceptors spread out in orbit around the Earth to ensure that at least one is always in range to intercept a missile during its boost phase," he said. But that means that if an adversary launches a salvo of ten missiles, some 9,500 interceptors would be needed to ensure at least ten are within range. "Given that China has about 350 intercontinental ballistic missiles and Russia has 306 -- not including their sub-launched ballistic missiles -- scaling a space-based interceptor system to meet the threat quickly becomes impractical." The non-partisan US Congressional Budget Office estimates that, just to stop "one or two intercontinental ballistic missiles", the United States would need a constellation of satellites costing between $161 billion to $542 billion. The US military could spend billions of dollars on research only for the next administration to nix the project, Harrison warned. "Golden Dome could become the poster child for waste and inefficiency in defence," he said. The plan also calls for developing satellites able to fire lasers at missiles to avoid too much debris on impact. But a European defence contractor said on condition of anonymity that such lasers are "still beyond what even the Americans are capable of doing". "It's just an excellent way to give the US (defence) industry substantial funding so they can increase their technological lead without necessarily aiming for actual operational deployment," the contractor said. 'Global arms race'? Trump's plan is reminiscent of President Ronald Reagan ambition for a Strategic Defense Initiative in the 1980s, which also sought to place interceptor satellites in space. China and Russia, which both have nuclear weapons, have slammed the latest plan as "deeply destabilising". Nuclear-armed North Korea has called the plan a "very dangerous" threat. Julia Cournoyer, research associate at Chatham House, said the plan was risky as adversaries would likely see it "as an attempt to undermine the logic of nuclear deterrence". "If Washington is perceived to be developing a shield that could one day neutralise a retaliatory nuclear strike, it risks triggering a dangerous global arms race," which would exacerbate rather than reduce risk. Withington said Trump might be hoping to use the plan as leverage for talks with China and Russia. "It may be that the Trump administration is hoping that this would bring both countries to some kind of negotiating table to talk about a reduction of nuclear warhead sizes or to revitalise the arms control agenda," he said.
France 24
6 hours ago
- Business
- France 24
French state leads capital increase for satellite operator Eutelsat
Paris's holdings will increase to just under 30 percent from 13 percent, Eutelsat said, in an overall deal set to be completed by the end of this year that will see 1.35 billion euros ($1.5 billion) injected into the company. The announcement comes as competition heats up in the satellite communications sector, where Elon Musk's Starlink is a dominant player but some governments are keen on sovereign solutions. "The race is on. That's why we have to take a position now and invest now. Otherwise, the whole market will be occupied and France and Europe will depend on other powers in future,' President Emmanuel Macron's office told AFP. Boasting more than 600 satellites since merging with British firm OneWeb in 2023, Eutelsat is the world's second-largest operator of low Earth orbit (LEO) satellites, behind Starlink, making it the obvious candidate as a European champion. The company has been pushing for new government contracts, signing a 10-year, billion-euro deal at this week's Paris Air Show to provide military communications for the French armed forces. Presenting its most recent quarterly results last month, Eutelsat said it was in active sales talks with governments both inside and outside Europe. The capital increase should allow Eutelsat to push ahead with renewing its satellite fleet, the company said. Major shareholders stumping up alongside Paris were shipping giant CMA CGM, Indian telecoms operator Bharti Airtel and the FSP investment fund, owned by seven French insurance companies. The two-stage plan includes a "reserved" capital increase open only to the four named investors, with a second round open to others. "Discussions are ongoing" with other investors including the British government, "which could join the capital raise in due course," Eutelsat said. "The capital increase would represent a pivotal step in Eutelsat's strategic and financing roadmap, enabling the execution of its strategic vision," it added, with other financial operations planned including debt refinancing.
