All About SpaceNo. 111的目錄

Radio bursts may spring from asteroids around magnetic stars Words by Charles Q. Choi ©NASA Mysterious repeating bursts of radio waves that fire in random patterns might come from neutron stars blasting asteroids with magnetic winds that travel at nearly the speed of light. Fast radio bursts, or FRBs, are intense pulses of radio waves that can give off more energy in a few thousandths of a second than the Sun does in nearly a century. Scientists only discovered FRBs in 2007, and much remains unknown about their origins because of their brief existence. The mystery of fast radio bursts deepened when scientists discovered the first repeating fast radio burst in 2016. When astronomers see repeating patterns in celestial events, they often think celestial mechanics might play a role: a…

INTERVIEW DARA Ó BRIAIN IS THERE ANYBODY OUT THERE? All About Space speaks to Stargazing Live co-host and astronomy-mad comedian Dara Ó Briain, who divulges how isolation has revealed the wonders of astrophotography, his memories of the BBC hit show and whether life could be out there somewhere in the cosmos Interviewed by Lee Cavendish ©Getty BIO Dara Ó Briain Ó Briain is an Irish comedian, science communicator, TV host and author. He studied mathematics and theoretical physics at University College Dublin (UCD), Ireland, before pursuing a career in comedy. His career has seen him co-host the BBC’s Stargazing Live with Brian Cox, and he has written a trifecta of space books aimed at young adults, the most recent one being Is There Anybody Out There? During the several months…

Challenger LESSONS NASA LEARNED One thing was clear following the Challenger disaster: crewed spaceflight could not stay the same NEW JOINTS AND SEALING SYSTEM Redesigned joints - which were already in production - and a new sealing system were implemented, with an inspection regime, in time for the next flight. This also added a third O-ring, and heaters to the joints. SAFETY, RELIABILITY AND QUALITY ASSURANCE The establishment of a new SR&QA office to oversee flight safety, though this did not go far enough to satisfy the Rogers Commission. The office reported directly to the NASA administrator. CREW ESCAPE SYSTEM The Crew Escape System was provided following the Challenger disaster. Previously the crew had no way of escaping their compartment. However, as the later Columbia disaster showed, it was only…

61 CYGNI: THE FLYING STAR 61 Cygni is an unremarkable star system – if not for its proximity to Earth Flying through the heavens The twin stars of 61 Cygni first drew attention to themselves because of their high proper motion against more distant background stars – they move across the sky at a rate equivalent to the width of a full Moon every 464 years. Heavenly pair The two stars orbit each other in around 680 years, and are currently separated by 18 seconds of arc – about the width of Saturn as seen from Earth – and so can be distinguished from each other using binoculars or a small telescope. Twin suns Both stars in the system are orange dwarfs – stars less massive than the Sun at…

TIMELINE OF THE DISCOVERY OF 61 CYGNI 1543 THE COPERNICAN REVOLUTION Copernicus published his influential argument that the Sun is at the centre of the Solar System. As evidence to support this idea mounted, astronomers hoped to clinch the argument by discovering stellar parallax. When they didn’t, they concluded that the stars must be very far away. 1718 PROPER MOTION Halley reported evidence that the positions of certain bright stars had shifted significantly since they were catalogued by ancient Greek astronomers. This was the first sign of proper motion – the slow rearrangement of the stars in Earth’s skies due to their motion through space. 1727 ABERRATION OF STARLIGHT While attempting to measure the parallax of the star Eltanin in Draco, Bradley discovered a shift in the apparent positions of…

2021’s unmissable space events METEOR SHOWERS 3 JANUARY QUADRANTIDS The first shower of the year is better for the Northern Hemisphere given the latitude of their origin, and if you hit lucky with the weather it can produce some good fireball meteors. 6 MAY AQUARIDS The Aquarids originate from Halley’s Comet and are expected to produce between 10 and 30 meteors an hour towards the end of the night. 12 AUGUST PERSEIDS The Perseids are the best known meteor shower, and in 2021 they will coincide with a new Moon, giving the best viewing conditions and potentially more than a meteor per minute. 14 DECEMBER GEMINIDS The Geminids are unusual in originating from an asteroid, 3200 Phaethon, which itself is an unusual colour for an asteroid – blue! A reliable…

ASK Space Our experts answer your questions SOLAR SYSTEM Why don’t Mercury or Venus have any moons? Planets have a region around them where orbiting objects can be gravitationally bound. In planetary science this is called the ‘Hill sphere’, named after 19th-century American astronomer George Hill, who worked on the Moon’s orbit. The size of the Hill sphere depends on how massive a planet is in comparison to the Sun, and how close it is to the Sun. Any bound object must orbit inside the Hill sphere. But for its orbit to be ‘stable’ it needs to orbit at less than about one-third of the radius of the Hill sphere. Therefore we expect that all moons must orbit at less than about a third of a Hill sphere radius. There…

STARGAZER Moon tour The Moon through your telescope If you’ve asked for an instrument for Christmas, or already have one, here’s what you can see on the lunar surface with it Source: Wikipedia Commons © Gregory H, Revera It’s true to say that during the lockdown earlier in the year many people discovered the natural beauty of the night sky for the first time; they had no idea that just by looking up from their gardens on a clear night they could see constellations, planets and much more. Many decided they wanted to see even more of the wonders of the universe, and will have received a telescope for Christmas. If you’re one of them you’ll be eager to turn it on the sky - and your obvious first target…

SpaceX launches next-gen GPS satellite for US Space Force Words by Amy Thompson SpaceX successfully launched an advanced GPS satellite for the US Space Force on 5 November, marking the first launch in nearly two weeks from Florida’s Space Coast. One of the company’s two-stage Falcon 9 rockets blasted off from Space Launch Complex 40 at Cape Canaveral Air Force Station, carrying the GPS III SV04 satellite to orbit. Nine minutes later the rocket’s first stage touched down on the deck of Of Course I Still Love You, one of SpaceX’s two drone ships. The GPS III SV04 mission had been set to follow on the heels of a United Launch Alliance (ULA) Atlas V rocket, which was scheduled to loft a US spy satellite from Cape Canaveral on 3…

Extragalactic planets WHY DO WE THINK THERE ARE PLANETS IN OTHER GALAXIES? We used to think that we were at the centre of everything. That the Sun, planets and stars all rotated around the Earth. The Copernican revolution changed all that, relegating us to just another planet orbiting the Sun. We realised that the stars were just distant copies of the Sun. Much of modern astronomy hinges on the idea that there’s nothing special about our place in the universe. This is called the Copernican principle. This means that if there are planets here there should be planets in other galaxies too. We also know that planets are a natural by-product of star formation - they form from the leftovers. Wherever we see stars, we also expect to see planets…

61 CYGNI THE STAR THAT CHANGED EVERYTHING In the newly released History of the Universe in 21 Stars (and 3 Imposters), the star 61 Cygni has been revealed to be the smoking gun in our understanding of the cosmos Written by Giles Sparrow © NASA; Getty Step outside and take a look at the early evening sky at this time of year and the constellation of Cygnus, the Swan, is hard to miss. This prominent cross shaped constellation hangs high overhead, looking like a swan with outstretched wings and a long neck stretching along the Milky Way towards the southern horizon. The bright-blue star Deneb marks the Swan’s tail high in the sky – the upper-left corner of the famous northern ‘Summer Triangle’ – while binoculars show that Albireo, on…

EXTENSIONS OF PARALLAX The ‘annual parallax’ method used by Bessel to measure nearby stars paved the way for other ingenious methods of distance measurement. Statistical parallax uses the proper motions of stars as a direct distance indicator on the assumption that, on average, more distant stars will move more slowly through the sky. Dynamical parallax calculates the size of the orbit in a binary star system and compares that to the stars’ measured separation in the sky. Cluster parallax methods use various tricks to guess the size or average proper motion of distant star clusters and therefore estimate their distance.…

Jupiter and Saturn JUNO AT WORK © NASA 1 Microwave radiometer (MWR) The MWR comprises six antennae mounted on two of the sides of the body of the probe, and is used by Juno’s operators to measure Jupiter’s atmospheric circulation and emissions. 2 Jovian Infrared Auroral Mapper (JIRAM) One of Juno’s most versatile instruments, JIRAM has been designed to acquire infrared images and study the spectra of Jupiter’s turbulent atmosphere. 3 JunoCam (JCM) One of Juno’s main imagers, the JunoCam is capable of taking visible-colour images of the Jovian cloud tops. Due to the high levels of radiation near Jupiter, it’s only set to survive eight orbits. 4 Gravity Science (GS) Juno’s onboard Gravity Science equipment is being utilised by NASA to test the composition of Jupiter via radio waves. It…

THE THEORIES What could the mystery object discovered in the mass gap actually be? Heaviest neutron star Since the object’s measurements place it at the lower end of the mass gap, it is closer in size to neutron stars than black holes. However, at 2.6 solar masses, it exceeds the limit for a neutron star’s maximum mass. This was thought to be 2.3, but astrophysicists at Goethe University Frankfurt set it as low as 2.16 in 2018. Most neutron stars have a mass of 1.4 solar masses. ©NASA Lightest black hole The most favoured explanation is a black hole, because no light was detected during the event of August 2019. This theory works because two merging black holes would not produce any light. But this could also be due to…

STARGAZER Naked eye targets Naked eye & binocular targets Orion dominates the winter sky after sunset. Here are some of its fascinating features and neighbours 1 Betelgeuse (Alpha Orionis) Shining at magnitude +0.6, this red supergiant, marking Orion’s shoulder, is the ninth-brightest star in the sky. 530 light years from Earth, it is 600 times the width of our Sun and would extend halfway to Jupiter if put in our Sun’s place. It will explode in a supernova in the future - but when? 2 Alnitak, Alnilam and Mintaka (Orion’s Belt) This striking line of three equally spaced blue-white stars is one of the most famous asterisms in the sky. Although its stars Alnitak, Alnilam and Mintaka all look the same distance from us, they are all spread far apart…

STARGAZER Christmas gift guide With the holiday season just around the corner, All About Space selects the presents that are sure to delight any space fan Best for all astronomers Celestron NexStar 4SE Cost: £479.99 (approx. $631.80) – price may vary From: wexphotovideo.com/celestron and other UK retailers The Celestron NexStar 4SE is a fully computerised and motorised telescope. After a brief set-up procedure, visible objects from your location can be selected on the hand controller and the telescope will move to them automatically. The 4SE will also continue to track the selected object as it appears to move across the sky, keeping it within the view of the eyepiece. The telescope tube is a powerful Maksutov-Cassegrain design, which allows for an extremely long focal length of 1,325mm in a compact…

LAUNCH PAD Strange rings suggest planets are formed earlier than thought Words by Charles Q. Choi YOUR FIRST CONTACT WITH THE UNIVERSE Rings detected around a newborn star may suggest that planets are born earlier than previously thought. Stars are born from dense clouds that collapse in on themselves under the force of their own gravity. As the blanket of gas and dust surrounding a nascent star, or protostar, shrinks over time, a disc forms around it that can give rise to baby planets, or protoplanets. In a new study, Dominique Segura-Cox, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and her team investigated IRS 63, a protostar located about 470 light years away in the constellation of Ophiuchus. Previous research found this protostar is…

Challenger MINUTE BY MINUTE WHAT HAPPENED DURING THE CHALLENGER DISASTER? The disaster was over quickly, but a lot happened in those 73 fatal seconds ©Science Photo Library 1 BLASTOFF T=0.00s As the command to ignite the solid fuel rockets is sent, mission specialist Judith Resnik can be heard to say, “All Right!” 2 BLACK SMOKE T+0.678s Smoke from just above the O-ring in Challenger’s right-hand booster is captured on film, but not seen until it is developed. 3 THROTTLE UP T+4.364s The main engine throttle is increased from 90 per cent to 104 per cent, as planned. 4 THROTTLE BACK T+19.885 Commands are sent to the main engines to throttle down to 94 per cent. 5 HIGH AND FAST T+28.000 The Shuttle reaches 3,050 metres (10,000 feet) in altitude and…

61 Cygni WHERE IS 61 CYGNI? Use our chart to find your way to the Flying Star ©NASA; Getty…

WHAT IS METALLIC HYDROGEN? 40,000 The estimated depth, in kilometres, of Jupiter’s metallic hydrogen layer. This is equivalent to about 24,850 miles. MORE HELIUM, LESS METAL Helium stabilises the hydrogen molecules inside gas planets, delaying the onset of metallisation. THE TRADITIONAL MIDDLE TIER In traditional models of gas planets, metallic hydrogen made up the inner layer. This distinction is now thought to be more fluid. AN OLD IDEA The metallisation of solid hydrogen was first predicted in 1935. FIVE PHASES Five non-metallic, solid phases of hydrogen have been identified so far, but more might be found in the future. NOT SOLID PLANETS Given their known conditions, it was thought that solid hydrogen couldn’t be formed in the core of giant planets. KEY TO MAGNETISM Metallic hydrogen is thought to be…

Jupiter and Saturn HOW SPOOKY SCIENCE HELPS US PEER INSIDE THE PLANETS MICHELE CERIOTTI An assistant professor of computational science at the EPFL research centre in Lausanne, Switzerland, involved in the current research on metallic hydrogen. Could you explain how the machine-learning techniques used in your research work? Why were they preferable to standard computational methods? The idea is very simple – this is basically using a very flexible functional form to interpolate the predictions of the energy and forces acting on atoms, as obtained by solving the Schrödinger equation. This basically gives you the same accuracy as the horribly complex – and computationally demanding – electronic structure calculations at a tiny fraction of the cost. This allows us to simulate larger systems for longer times, getting us closer to…

THE MASS GAPS BY THE NUMBERS 2.6 Size in solar masses of the discovered object 23 Size in solar masses of the black hole 3, 000 Number of kilometres between the two detectors making up LIGO 2019 Year the object was discovered, on 14 August 20 Diameter of a neutron star’s core in kilometres 8 BILLION tonnes in a single teaspoon of neutron star matter 800, 000, 000 light years to the object’s location from Earth 6X farther away than a merger discovered in 2017 25 Size in solar masses of the final black hole produced by the merging of the two objects…

Neutron stars and black holes WHAT GAPS IN OUR KNOWLEDGE REMAIN? Maya Fishbach is a postdoctoral fellow at Northwestern University and a member of the LIGO Scientific Collaboration Could there still be a mass gap? We still need more observations of compact objects before we can definitely conclude whether or not there is a mass gap – and where it is located. This is exactly what I’m trying to figure out with more gravitationalwave data from LIGO and Virgo. My collaborators and I analysed the first 11 observations from LIGO and Virgo, which included ten binary black holes – with masses bigger than around seven solar masses – and one binary neutron star – with masses smaller than two solar masses. However, this was before GW190814, with the 2.6 solar…

STARGAZER Deep sky challenge The Hunter’s hidden treasures If you can drag your eyes away from its most famous nebula, you’ll find lots of lesser known but fascinating deep-sky objects © ESO 2020 is almost over – good riddance, many will say – but hopefully December will bring with it some sparkling clear and frosty nights for us to sweep with our telescopes. Obviously we will all swing our reflectors and refractors towards the Orion Nebula (Messier 42) and lose ourselves in its clouds of green and grey, but the constellation of Orion has much more to offer than just that faraway stellar nursery. Scattered around ruddy Betelgeuse, searing Rigel and the Belt are a wealth of other fascinating objects definitely worth aiming your telescope at. But a word of…

HEROES OF SPACE Guion Bluford He was the first African American astronaut to fly into space Guion Bluford applied to become a NASA astronaut in 1977, but he didn’t hold out much hope. After all, it was the first time in ten years that applications had been sought, and he was acutely aware that 8,079 people had applied – with just 35 places on offer. Yet Bluford was always in with a very good chance. As an officer and fighter pilot in the US Air Force, he’d received his pilot wings in January 1965. He’d gone on to fly 144 combat missions with an F-4 squadron in Vietnam before teaching cross-country and acrobatic flying and gaining a master’s degree in aerospace engineering in 1974. He also graduated four years later…