A chance to spot rare and mysterious noctilucent clouds
It's time to watch for the beautiful cloud formations known as noctilucent clouds. Latin for 'night shining', noctilucent clouds are seasonal and become visible in the northern hemisphere from late spring/early summer.
Although unpredictable, when they do appear they will be seen in the western sky about half an hour after the sun sets. As the sky darkens into night, they will shine with an extraordinary electric blue colour.
Part of the appeal of these rare clouds is that their origins are still mysterious. They are the highest known clouds in Earth's atmosphere, condensing at an altitude of about 80km (50 miles). This is virtually the edge of space. Their extreme altitude is what allows them to catch the last rays of the setting sun, even when Earth's surface beneath them is already in darkness.
Perhaps the most puzzling aspect of the clouds is that there are no recorded sightings of them before 1885. Some suggest the clouds are therefore caused by industrial pollutants to which water vapour freezes, or by the rise of the greenhouse gas methane in the atmosphere, which promotes water vapour production in the upper atmosphere.
In the southern hemisphere, the noctilucent cloud season begins around October.
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The Guardian
9 hours ago
- The Guardian
‘It's something that happens': are we doing enough to save Earth from a devastating asteroid strike?
It is a scenario beloved of Hollywood: a huge asteroid, several miles wide, is on a collision course with Earth. Scientists check and recheck their calculations but there is no mistake – civilisation is facing a cataclysmic end unless the space rock can be deflected. It may sound like science fiction, but it is a threat that is being taken seriously by scientists. Earlier this year, researchers estimated that asteroid YR4 2024 had a 3.1% chance of hitting Earth in 2032, before revising that likelihood down to 0.0017%. This week, new data suggested it was more likely to hit the moon, with a probability of 4.3%. If that happens, the 53- to 67-metre (174ft-220ft) asteroid previously called a 'city killer' will launch hundreds of tonnes of debris towards our planet, posing a risk to satellites, spacecraft and astronauts. Before that, in April 2029, 99942 Apophis – an asteroid larger than the Eiffel Tower – will be visible to the naked eye when it passes within 32,000km of Earth. This attention-grabbing close encounter has prompted the UN to designate 2029 as the international year of planetary defence. When it comes to apocalyptic asteroid strikes, there is precedent, of course. Most scientists believe such an event hastened the demise of non-avian dinosaurs 66m years ago. 'This is something that happens,' said Colin Snodgrass, a professor of planetary astronomy at the University of Edinburgh. 'Not very often, but it is something that happens. And it's something that we could potentially do something about.' As Chris Lintott, a professor of astrophysics at the University of Oxford, told the UK parliament's science, innovation and technology committee this week, the risk posed by an asteroid originating beyond our solar system is minimal. Instead, he said, the greater threat comes from those in our cosmic back yard. 'Most asteroids in the solar system exist in the asteroid belt, which is between Mars and Jupiter, but they become disrupted, usually by encounters with either of those planets, and they can move into orbits that cross the Earth,' said Lintott, who presents the long-running BBC astronomy series The Sky at Night. 'Then it's just a case of whether we're in the wrong place at the wrong time.' The chances of an enormous asteroid – the type that did for the dinosaurs – hitting Earth is admittedly low. 'We think there's one of these every 10m to 100m years, probably,' Lintott told the Guardian. 'So I think you'd be right to ignore that when you decide whether to get up on a Thursday morning or not.' Snodgrass said there were 'precisely four' asteroids big enough and close enough to Earth to be considered 'dino-killers', and added: 'We know where they are, and they're not coming anywhere near us.' But damage can also be done by smaller asteroids. According to Nasa, space rocks measuring about one to 20 metres across collided with Earth's atmosphere resulting in fireballs 556 times over 20 years. Many collisions have occurred over the oceans, but not all. 'Chelyabinsk is the best example,' Lintott said. In 2013, a house-sized space rock – thought to have been about 20 metres across – exploded in the air above the Russian city with a force of nearly 30 Hiroshima bombs, producing an airburst that caused significant damage and hundreds of injuries, mostly from broken glass. Less dramatically, in February 2021 a space rock thought to have been just tens of centimetres across broke up in Earth's atmosphere, with fragments landing in the Cotswold town of Winchcombe in the UK. Thankfully, the damage was confined to a splat mark on a driveway. The types of asteroids we should perhaps be most concerned about are those about 140 metres across. According to Nasa, asteroids around that size are thought to hit Earth about once every 20,000 years and have the potential to cause huge destruction and mass casualties. The space agency has a congressional mandate to detect and track near-Earth objects of this size and larger, and a suite of new technological advances are helping them do just that. On Monday, the first images from the Vera C Rubin observatory in Chile were released to the public. This telescope is expected to more than triple the number of known near-earth objects, from about 37,000 to 127,000, over a 10-year period. In just 10 hours of observations, it found seven previously unspotted asteroids that will pass close to the Earth – though none are expected to hit. Also in the offing, though not planned for launch before 2027, is Nasa's near-Earth object (Neo) surveyor. Armed with an array of infrared detectors, this is 'the first space telescope specifically designed to detect asteroids and comets that may be potential hazards to Earth', the agency says. Lintott said: 'Between those two, we should find everything down to about 140 metres.' He said such observations should give scientists up to 10 years' warning of a potential collision. The European Space Agency (Esa) is planning a near-Earth object mission in the infrared (Neomir) satellite. Slated for launch in the early 2030s, this will help detect asteroids heading towards Earth that are at least 20 metres in diameter and obscured by the sun. Assessing the emerging capabilities, Edward Baker, the planetary defence lead at the UK's National Space Operations Centre (NSpOC) at RAF High Wycombe, said: 'I think we're in a good place. I can't see a situation like [the film] Don't Look Up materialising at all – though I wouldn't mind being portrayed by Leonardo DiCaprio.' As our ability to spot near-Earth asteroids increases, Lintott said, we should get used to hearing about asteroids like YR4 2024, which initially seem more likely to hit Earth before the risk rapidly falls towards zero. He described the shifting probabilities as similar to when a footballer takes a free kick. 'The moment they kick it, [it looks like] it could go anywhere,' he said. 'And then as it moves, you get more information. So you're like: 'Oh, it might go in the goal,' and then it inevitably becomes really clear that it's going to miss.' Of course, scientists aren't just monitoring the risks to Earth. They are also making plans to protect it. In 2022, Nasa crashed a spacecraft into a small, harmless asteroid called Dimorphos that orbits a larger rock called Didymos to test whether it would be possible to shift its path. The Dart mission was a success, reducing Dimorphos's 12-hour orbit around Didymos by 32 minutes. In 2024, Esa launched a follow-up to Nasa's Dart mission, called Hera. This will reach Dimorphos in 2026 and carry out a close-up 'crash site investigation'. It will survey the Dart impact crater, probe how effectively momentum was transferred in the collision and record a host of other measurements. Esa hopes this will provide crucial insights that can be used to make deliberate Dart-style impacts a reliable technique for safeguarding Earth. 'Dart was much more effective than anyone expected it to be,' Lintott said. 'And presumably that's something to do with the structure of the asteroid. I think we need to know whether Dart just got lucky with its target, or whether all near-Earth asteroids are like this.' For the most part, scientists say the threat of an asteroid strike does not keep them up at night. 'We're safer than we've ever been and we're about to get a lot safer, because the more of these things we find, the more we can spot them on the way in,' Lintott said. As Esa has quipped on its merchandise: 'Dinosaurs didn't have a space agency.'
BBC News
a day ago
- BBC News
Oldest rocks in the world are in Canada scientists say
Scientists think they have found the oldest rocks on ancient rocks were found in the Nuvvuagittuq Greenstone Belt, in Quebec in Canada, and for the last two decades scientists have been studying they hadn't been able to agree on an accurate age for the rocks, until teams using two different dating methods had produced different ages for the rocks: 4.3 billion and 3.8 billion years the latest study says the rocks are actually 4.16 billion years old! How did scientists test the old rocks? The scientists used both the techniques from previous tests, but focussed in on just one type of rock that made up the stripy stones. This type of stone is called metagabbro and is a rock that formed under huge heat and pressure inside the planet's crust billions of years tests brought back the same result this time - the rock was 4.16 billion years rocks are from one of the earliest periods on Earth, known as the Hadeon Earth was formed around 4.5 billion years ago and rocks from this time are an incredibly rare, as the movement of the Earth's tectonic plates mean that many have been melted and O'Neil, who led the study in the Science journal said the rocks give a "unique window into our planet's earliest time to better understand how the first crust formed on Earth".He added that because some were formed through ancient seawater, they shed light on the first oceans and "help established the environment where life could have begun on Earth."
Daily Mail
a day ago
- Daily Mail
US general warns China is winning the military space race
China's space-based military technology is developing 'breathtakingly fast' with US forces at risk of the 'kill chain', Washington has warned. Beijing have been catching up in the arms race to develop missile technology that can be sent from space at a 'very concerning rate', the top commander of the US Space Force (USSF) added. The so-called kill chain - which identifies, tracks and attacks a target - could be used on US and allied forces in the Indo-Pacific as well as 'over-the-horizon' precision strikes, General Stephen Whiting told The Telegraph. The warning comes only a month after Donald Trump unveiled his own plans for a $175 billion 'Golden Dome' defence system which he says will protect the US from the world's most powerful weapons. The integration of space-tech with China's army, navy and air force has made them 'more lethal, more precise and more far-ranging' - and could take the lead from the US in the space-arms race. Earlier this year, the USSF said that China had conducted several synchronised satellite manoeuvres in low Earth orbit, also known as 'dogfighting'. 'They are practicing tactics, techniques, and procedures to do on-orbit space operations from one satellite to another,' General Michael Guetlein, the Deputy Chief of US Space Operations at the USSF, said. He added: 'There used to be a significant capability gap between the United States and our adversaries, driven by our technological advantage. 'That gap, once massive, has narrowed considerably. 'If we don't change our approach to space operations, we risk seeing that gap reverse, putting us at a disadvantage.' China has more than 500 satellites capable of intelligence, surveillance and reconnaissance (ISR), with 67 sent up in the last year alone, the USSF said in 2024. The 'space enabled services' are broken down into three units - a cyberspace army, an aerospace force, and an information support arm. While America have around 8,000 satellites in space compared to China's 1,000 in total, Chinese scientists have also recently developed what is considered the world's most powerful satellite tracking camera. Pictured: Stephen Whiting. The technology is able to take pictures with millimetre level accuracy more than 60 miles away. Chinese satellites are also working towards counter-weapons development that would see other satellites jammed, destroyed or 'spoofed' - which is where the GPS receiver is misled or manipulated. Exerts have previously warned that the US is underprepared for such developments, with the first test done in 2008 where a satellite in space was shot down with a missile on the ground. But the latest developments could redirect drones, disable munitions or missiles and shut down crucial infrastructures. China's long-range weapons that strike with precision 'depend on space' and is how Beijing 'closes its kill chain', the USSF commander of the Indo-Pacific region, Gen Anthony Mastalir, has previously warned. Trump's Golden Dome proposal was 'long overdue' and 'absolutely necessary' amid growing threats from China, North Korea and Russia, experts said at the time. But Beijing warned that the plan to put US weapons into the earth's orbit for the first time 'heightens the risk of space becoming a battlefield, fuels an arms race, and undermines international security.' Meanwhile Moscow called for Washington to make contact regarding the programme - to which Trump said he would do so 'at the right time'.
