All About SpaceNo. 110的目錄

WELCOME Issue 110 It’s a groundbreaking finding that suggests there could be life elsewhere in the Solar System: the discovery of phosphine on Venus. One of the most hostile worlds in our solar neighbourhood isn’t the first place that springs to mind in our search. But what’s so important about phosphine, and why has it made us so excited? Colourless, flammable and incredibly toxic, phosphine was found in the clouds of the Venusian atmosphere. It’s in a place where it shouldn’t be, and while it could be explained by processes so far unheard of, the research team, led by Jane Greaves at Cardiff University, suspect that it could relate to life. “I thought, well, just before we throw this away, I’ll have a final go at [analysing the data],” Greaves…

LAUNCH PAD YOUR FIRST CONTACT WITH THE UNIVERSE IN COOPERATION WITH SPACE.COM Physicists attempt to break the rules of gravity Words by Rafi Letzter © Event Horizon Telescope collaboration etal. A new test of Albert Einstein’s theory of general relativity has proved the iconic physicist right again-this time by reanalysing the famous first-ever picture of a black hole, which was released in April 2019. That image of the supermassive black hole at the centre of galaxy Messier 87 is the first direct observation of a black hole’s shadow – the imprint of the event horizon, a sphere around the black hole’s singularity from which no light can escape. Einstein’s theory predicts the size of the event horizon based on the mass of the black hole, and in April 2019 it…

Life on Venus IS THERE LIFE ON VENUS? A discovery in the cloud decks of the hostile planet could be the smoking gun for astrobiologists Reported by Lee Cavendish © NASA; ESA ESO; Tobias Roetsch Could life be floating around in the clouds of Venus? Does Earth’s sister planet have habitable conditions above the hellscape that is its surface? Have astrobiologists just found another target in the Solar System they should be investigating? These are just some of the questions that have recently come to attention after research led by Professor Jane Greaves of Cardiff University found phosphine, a potential biosignature, in the atmosphere of Venus. Phosphine – a molecule made up of one phosphorus atom and three hydrogen atoms – is a rare find. It can be created through…

Supergiant galaxies HOW BIG GALAXIES ARE MADE Giant galaxies and other massive ellipticals go through a series of changes on their way to becoming the monsters of the present-day universe © Tobias Roetsch 1 Big Bang Around 13.8 billion years ago The universe began in a vast explosion that gave rise to space, time and all matter. The Big Bang left behind large-scale differences in the distribution of both normal ‘luminous’ matter and the far more plentiful invisible ‘dark’ matter. Dense patches of matter formed the nuclei around which the first stars and galaxies began to coalesce. 2 Merger Around 12 billion years ago The first galaxies to form were gas-rich, systems full of young, massive and short-lived stars. Collisions and mergers between these small galaxies were frequent, and large…

The hunt for wormholes HOW WORMHOLES ARE MADE If these space-time tunnels do exist, what would they look like and how would they come into existence? © Getty 1 Collapse of the core When a gigantic star – with a mass much more than 20 times the mass of the Sun – dies, sometimes a black hole is formed. When we refer to a star dying, we mean that it no longer has any nuclear fuel to burn, and this means that gravity is unable to override an outward force. The core has no choice but to collapse in on itself in the catastrophic explosion of a supernova. The devastated star’s outer layers are expelled into space while the core continues to shrink in size. 2 A cosmic plughole Shrinking…

Magnetasrs Focus on SCIENTISTS SPOT MAGNETARS’ MISSING LINK These magnetic stars might be more like pulsars than originally suspected ©ESO Researchers have apparently found a ‘missing link’ between two types of pulsars. Pulsars are fast-spinning neutron stars, the superdense, collapsed cores left over from the explosive deaths of massive stars. Pulsars emit beams of radiation from their poles that appear to pulse when they’re observed from Earth, hence the name. Pulsars don’t actually pulse, though – that’s an effect of their rotation. Scientists had thought that two different kinds of pulsars – magnetars, which sport extremely powerful magnetic fields, and rotation-powered pulsars – emit their beams in different ways. But a new study suggests that these extreme objects have more in common than was previously presumed. “Our study has given…

Phantom energy DARK MATTER’S RADIATION AND GRAVITY Whatever comprises dark matter, even darker elements could be responsible for its behaviour DARK MATTER What could dark matter be made of? Higgsino The super-partner of the Higgs boson, if the comprised dark matter then it would have a mass of 1.783 kilograms x 1024, which is massive for a particle. Dark neutrons Dark electron Dark photons Another proposed ‘dark force carrier’ for dark matter, dark photons are elementary particles that could be seen by mixing with the particles of light we know as photons, along with how they affect the interactions between known particles. DARK RADIATION Whatever particle comprises dark matter, some believe that dark electromagnetism mediates the interactions of its constituents. Axion These particles, if they exist and have a low…

ASK Space Our experts answer your questions SOLAR SYSTEM What will happen to the Solar System when the Sun becomes a white dwarf? For the last 4.5 billion years the Sun has provided warmth and light to Earth, thanks to a constant chain of nuclear reactions in its core. But what will happen to our planet, and the rest of our Solar System, when the Sun runs out of its nuclear fuel? In about 8 billion years the Sun will swell 200-times larger than its current size, engulfing most of the inner Solar System – Mercury, Venus and possibly Earth – and briefly baking the outer planets – Jupiter, Saturn, Uranus and Neptune. After completely exhausting its fuel reserves, the Sun will shed its outer layers, leaving only a tiny, dense…

STARGAZER Moon tour The far side of the Moon What wonders can be found on the mysterious side of the Moon which we can never see? Even the most enthusiastic Moon-watcher sometimes feels frustrated that we only ever see one side of our Moon, dubbed the near side. Because the Moon is tidally locked with Earth it spins around on its axis at the same speed at which it orbits our planet, so we always see the same side. Our side is magnificent, no doubt about that, but every lunar observer has looked up at the Moon at some point and wished that just once they could see its farthest limb with their own eyes and through their telescope. The side of the Moon which is always hidden from our…

Six galaxies found trapped around a supermassive black hole Words by Elizabeth Howell ©ESO New data from the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile and other observatories gives astronomers a sense of black hole evolution when the universe was less than a billion years old. One mystery of supermassive black holes is how they got so large, some containing billions of times the mass of the Sun. Supermassive black holes are also relatively common: they lurk at the hearts of most, if not all, galaxies, including our own Milky Way. The new observations give fuel to the idea that such black holes grow in gassy environments within large, web-like structures. “This research was mainly driven by the desire to understand some of the most challenging astronomical…

‘Superflares’ may make it hard for life to begin around dwarf stars Words by Mike Wall Powerful stellar eruptions could pose a serious challenge to the origin and evolution of life around the universe. Such outbursts throw off large amounts of ultraviolet (UV) radiation, which is not only directly harmful to life as we know it, but can also strip away the atmospheres of relatively close-orbiting planets. These issues are especially pronounced for worlds circling red dwarfs. Red dwarfs are more active than Sun-like stars, especially when they’re young. Because each red dwarf is so dim, their ‘habitable zone’ is much closer in. “We found planets orbiting young stars may experience life-prohibiting levels of UV radiation, although some microorganisms might survive,” said Ward Howard, a doctoral student in the Department…

Life on Venus EARTH VS VENUS Sometimes called ‘Earth’s Twin’, Venus is in fact a very different world to ours ©Tobias Roetsch; © NASA/JPL-Caltech AVERAGE DISTANCE FROM THE SUN 150 MILLION KILOMETRES (93 MILLION MILES) PLANET RADIUS 6,378 KILOMETRES (3,963 MILIS) PLANET DENSITY 5,520 KILOGRAMS PER CUBIC METRE SURFACE TEMPERATURE 15 DEGREES CELSIUS (59 DEGREES FAHRENHEIT) ATMOSPHERIC COMPOSITION 78% NITROGEN, 21% OXYGEN, 1% ARGON AVERAGE DISTANCE FROM THE SUN 108 MILLION KILOMETRES (67 MILLION MILES) PLANET RADIUS 6,052 KILOMETRES (3,760 MILES) PLANET DENSITY 5,250 KILOGRAMS PER CUBIC METRE SURFACE TEMPERATURE 465 DEGREES CELSIUS (869 DEGREES FAHRENHEIT) ATMOSPHERIC COMPOSITION 96% CARBON DIOXIDE, 3% NITROGEN…

WHAT IS A WORMHOLE? There’s more than one type of shortcut for long journeys across and beyond the universe Type 1: connecting our universe to itself This is the transport mechanism used by the crew of astronauts in the film Interstellar as a shortcut between our Solar System and a distant galaxy. Einstein’s general theory of relativity suggests it might be possible to bend space-time sufficiently to bring you and your destination much closer together. Type 2: our universe connects to another The equations of Einstein’s general theory of relativity blow up in a fever of infinities at the bottom of a black hole. Replacing them with a slightly modified set of rules suggests that a wormhole to another universe might exist in its place. But we do not have…

The hunt for womholes HOW DO WE KNOW IF WE’VE FOUND A WORMHOLE? There are several clues to look out for if we find a candidate for a space-time portal ©Tobias Roetsch Gravitational-wave ringdown echo The gravitational waves from colliding black holes die away very quickly, but two colliding wormholes would produce an echo detectable with the next generation of experiments. source: Wikipédia Commons ©PúbÍic Domain Microlensing lf a wormhole passed in front of a distant star it would bend the star’s light slightly in an event called ‘microlensing’. This technique has already been used to find rogue planets. ©NASA Heading into one Some scientists believe that black holes are actually wormholes in disguise. It’s a risky endeavour, but sending something into one would let us know for certain if…

Phantom energy SHEDDING LIGHT ON PHANTOM ENERGY AND THE DARK SIDE OF THE UNIVERSE Understanding the ‘undetectable’ cosmos could well lead to significant changes in some highly cherished theories that govern space-time Reported by Paul Cockburn ©Shutteistock We live in an age of precision cosmology. As we continue to observe and study the universe around us using ever more precise instruments and increasingly sophisticated data- processing systems, the findings have invariably proven to be unexpected – if not frankly bizarre. Perhaps the most famous of these findings was the gradual realisation that everything we can see in the universe – every dust cloud, asteroid field, planet, star, nebula and galaxy cluster – simply doesn’t have sufficient mass to ensure that the universe behaves in the way it clearly does –…

LAUNCH PAD YOUR FIRST CONTACT WITH THE UNIVERSE © NASA/ESA Jupiter and its moon Europa On 25 August 2020, NASA/ESA’s Hubble Space Telescope conducted its annual check-up on Jupiter leading astronomers to try and understand how the planet’s turbulent atmosphere shifts and changes. In the same image is the gas giant’s moon Europa but the interesting detail here is the bright- white storm that’s travelling at 560 kilometres (350 miles) per hour at the midnorthern latitudes. Erupting on 18 August 2020, weather systems like this usually only pop up once every six years but this specimen offers the chance to study a young and evolving Jovian storm. ©NASA/JPL-Caltech Enceladus in infrared Although NASA’s Cassini spacecraft plunged to its death through Saturn’s atmosphere on 15 September 2017, the data it collected…

Star is seen being shredded by ‘spaghettification’ Words by Elizabeth Howell Telescopes have captured the rare light flash from a dying star as it was ripped apart by a supermassive black hole. This rarely seen ‘tidal disruption event’ – which creates spaghettification in stars as they stretch and stretch – is the closest such known event to happen at only 215 million light years from Earth. One light year is the distance light travels in a year, equating to about 10 trillion kilometres (6 trillion miles). “The idea of a black hole ‘sucking in’ a nearby star sounds like science fiction. But this is exactly what happens in a tidal disruption event,” said Matt Nicholl, a lecturer and Royal Astronomical Society research fellow at the University of Birmingham, UK. Researchers…

Cosmonauts patch air leak on the ISS Words by Meghan Bartels ©Adrian Mann Cosmonauts are making progress in the fight against the small air leak that has beleaguered the International Space Station (ISS) for months. The leak was first detected in September 2019 but was too low a priority for NASA and Roscosmos to address until August of this year given the short staffing and high activity rates at the orbiting laboratory. In August NASA announced a few measures that Roscosmos was undertaking to track down the leak’s location. Those steps included two crew weekend sleepovers on the Russian segment to isolate components of the station. At no point has the leak threatened the space station or the astronauts living on it. Cosmonauts report that they tracked down the leak…

Life on Venus HOW THE DETECTION WAS MADE Two observatories in Hawaii and Chile were used to find phosphine’s spectral signature © ALMA; ©William Montgomerie; © ESO 1 STARTING WITH THE JCMT This discovery was made by performing a spectroscopic analysis of Venus’ atmosphere using the JCMT in Hawaii, which is operated by the East Asian Observatory. The objective was to intentionally search for phosphine, a potential biosignature, in the planet’s thick atmosphere. 2 THE FIRST HINT OF PHOSPHINE After analysing the’data collected, by the JCMT, Greaves noticed a dip in the spectrum at 1.123 millimetres. This absorption of radiation spotted in Venus spectrum corresponds to the potential presence of phosphine molecules. However, this analysis alone was not enough proof. 3 FOLLOWED UP WITH ALMA ALMA is possibly the busiest…

Future tech Athlete ATHLETE If we are to settle on other planets in the Solar System, we will need machines for heavy lifting in all manner of environments. NASA is working on such a robot already © AdrianMann ©NASA/JPL-Caltech The All-Terrain Hex-Limbed Extra-Terrestrial Explorer, or ATHLETE, is NASA’s concept for a heavy-lift utility robot to help human exploration by carrying loads over long distances. Starting in 2005, the project has built and tested two generations based around an ingenious multipurpose structure. ATHLETE has six limbs fixed around a central ring. The limbs have multiple joints that allow the ends to be moved back and forth, up and down, side to side and angled around all three axes as well. Each limb has a wheel on the end with its own…

Exoplanet hunter Focus on A WEIRD WORLD AROUND A WARPED STAR The spacecraft CHEOPS has categorised a strange new exoplanet with an odd orbit ©Mark Garlick Europe’s new telescope studying alien planets has created its first detailed portrait of a world, and it’s a weird one: hot and tilted around a warped star. The European Space Agency (ESA) launched the CHaracterising ExOPlanets Satellite, nicknamed CHEOPS, in December 2019; the spacecraft began science observations in April. CHEOPS isn’t designed to discover alien planets, but rather to inform scientists so that they can construct portraits of the worlds. In the mission’s first results, scientists on the CHEOPS mission have done just that, forming a detailed picture of the planet WASP-189b, which was first detected in 2018. “This first result from CHEOPS is…

WHERE SCIENTISTS THINK WORMHOLES MIGHT EXIST Where these portals through space-time could be hiding Centre of the Milky Way In 2015 Italian researchers suggested there could be a wormhole lurking in the centre of the Milky Way some 27,000 light years away. Ordinarily a wormhole would need some exotic matter to keep it open, but researchers believe dark matter might be doing the job. © ESO Inside a black hole Rather than having a singularity at the centre as general relativity predicts, some researchers believe we’d find a wormhole – one that could allow us to make the journey from Interstellar a reality. However, the jury is still out on whether it would be big enough for a human to traverse. © NASA Quantum foam Even empty space isn’t truly…

The hunt for wormholes IF THEY EXIST, COULD WE TRAVEL THROUGH A WORMHOLE? YES “The possibility of using wormholes to travel is not completely excluded at a theoretical level. However, to even create a wormhole requires exotic matter that we have never seen here on Earth.” Vitor Cardoso University of Lisbon, Portugal NO “The problem is that usually these wormholes are very small, and when I say small, I mean really, really small, so it is not possible for a real observer to pass through that wormhole.” Diego Rubiera-Garcia Complutense University of Madrid, Spain…

Phantom energy PHANTOM ENERGY AND THE EXPANSION OF THE UNIVERSE This mysterious form of dark energy could very well cause our cosmos to end by being torn apart ©Nicholas Foider 1 The Big Bang Some 13.8 billion years ago, the universe began in a rapid expansion that originated from an area of high temperatures and high density. 2 Universe begins to inflate Not long after the birth of the universe, an inflationary period begins and ends within much less than a second. Today the cosmos continues to expand, but at a much slower rate. 3 The Dark Ages For 150 million years the universe is transparent, without any large-scale structures. During this time the only real radiation was the so-called hydrogen line – when there’s a change in the energy…

Rocket engines Instant expert HOW DOES A ROCKET WORK? A rocket engine profits from one basic priciple: as it propels material in one direction, it receives a kick in the other. Whether it’s a child on ice skates who throws a stone forward and finds themselves gliding backwards or a modern rocket leaving Earth’s surface, the physics of conserving momentum underwrites the drama. Does the rocket need to have a flame to be effective? Not in principle. Some smaller thrusters have simply puffed vapour away from the direction they want to travel. Even a slow leak or evaporating water have provided a small kick to nudge a craft from its intended course. But a launch-worthy rocket engine uses what engineers have sometimes called a ‘controlled explosion’ to provide an incredible…