All About SpaceNo. 97的目錄

Welcome © Nicholas Forder What is phantom energy? You'd be correct in thinking that its cousin is the mysterious dark energy. And just like it, cosmologists are scratching their heads on its true identity. We have a rough idea that dark energy exists in the universe due to cosmic expansion, but currently we're still trying to prove the existence of its ghostly relative. You'll remember that the Hubble Space Telescope revealed that the cosmos is expanding quickly – or at least much faster than we initially measured – now we could have an explanation for it, and phantom energy could be the culprit. What does this mean for the fate of the cosmos? Essentially, when anything expands too quickly, it tends to tear, and the universe is of no exception:…

A slice of Red Planet ©ESA The European Space Agency’s Mars Express satellite has beamed back excellent close-up images of the Martian surface over the years, and here is another one to add to the collection. This long slice of Mars shows the north pole’s ice caps, and moving south there are craters and scars scattered over the Terra Sabaea and Arabia Terra regions. These close-up images can be taken for granted, but it is important to realise that at the centre of this image, a pixel equates to just one kilometre (0.6 miles) – an incredible capability for a spacecraft that continues to reveal important details about the Red Planet.…

Phantom energy The Big Rip: how the universe could end Phantom energy appears to be pushing the cosmos apart, and the potential result isn't pretty © Tobias Roetsch Galaxy formation Dark matter began to merge and clump, with galaxies and stars forming from clouds of gas due to gravity. Other objects were drawn in to make the galaxies larger. Cosmic inflation The universe exponentially expanded by a huge amount in just a fraction of a second, scattering matter and energy. It's unclear what drove it. Ever-faster expansion Gravity slowed cosmic expansion, but dark energy – in this case phantom energy – overwhelms it, causing ever-faster expansion with the universe. The Big Bang Dark matter and dark energy are understood to have originated at the point of the Big Bang about…

Exploring the past and future of the swift planet © NASA © NASA Visiting Mercury is a dangerous and difficult task. Some may think that this is because it’s a relatively small planet and therefore more difficult to navigate to, but that is far from the case. The voyage to Mercury is difficult because of the humongous ball of searing plasma, the Sun, and its pesky gravity. Navigating a spacecraft to Mercury requires propulsion that will get it to Mercury and also counteract the gravity of the Sun so the craft doesn’t go falling into the surface and burn up. This is why only two spacecraft have ever visited the small terrestrial planet. NASA has been the operator of both of these missions, the first being Mariner 10 in 1974,…

Alien caves We have found evidence of subterranean environments under the surface of a number of Solar System worlds Earth Earth’s caves have provided a shelter for humans and our ancient ancestors for over a million years, as evidenced by fossilised remains and cave wall art. As well as lava tubes similar to those found on Mars and the Moon, Earth’s atmospheric water cycles mean you also find caves within karst landscapes where water dissolves away limestone, creating a subterranean world of caverns, springs, aquifers and sinkholes. ©Shutter stock The Moon Due to our Moon’s lower gravity it was long suspected that subsurface lava flows might create extensive lava tube networks, far bigger than anything on Earth. In 2017 JAXA reported a discovery that seemed to support such a theory.…

Mission profile: Fermi Gamma-ray Space Telescope How astronomers were first able to discover the lobes of the Fermi Bubbles © NASA Collecting gamma-ray data The Fermi Gamma-ray Space Telescope which launched on 11 June 2008 observes light in the photon energy of between 8,000 and 300 billion electronvolts. It collected the data which astronomers Douglas Finkbeiner, Tracy Slatyer and Meng Su used during their discovery of the Fermi Bubbles. Gamma-ray Burst Monitor This instrument includes 12 detectors on opposite sides and facing different directions. They are made of sodium iodide to catch X-rays and low-energy gamma rays. When hit, a flash of light emits that can be detected by a photomultiplier tube. Comparing the rate of signals from different detectors determines where the rays came from. High-energy detectors The Gamma-ray…

STARGAZER Mercury’s transit of the Sun On the afternoon of 11 November something quite rare will be happening in the sky – but you’ll need special observing techniques and equipment if you’re going to see it. Here’s our guide © NASA What is happening? Sky-watchers across the UK and around the world will be crossing their fingers for a cloud-free sky on the afternoon of 11 November to allow them to see one of the rarest events in astronomy. Between 12:36 and 18:04 on that day the Sun, Earth and the planet Mercury will be perfectly aligned. Despite what the internet’s doom-mongers will inevitably predict, this alignment won’t result in any Hollywood disaster movie shenanigans – there’ll be no earthquakes, tidal waves or interdimensional portals opening – but it will…

Planet of the month Mercury Constellation: Libra Magnitude: 2.8 to -0.4 AM/PM: PM Although it is usually so hard to see, this is a very big month for the closest planet to the Sun and for those who like to observe it. As far as observing is concerned, Mercury is one of the ‘forgotten’ worlds of the Solar System. Along with distant Uranus and Neptune, it is considered by many amateur astronomers to be too difficult to see. At the start of the month that is the case, with Mercury too close to the Sun to be visible in the sky, setting only a few minutes after our star and growing closer and closer to it every day. But bizarrely, when Mercury actually moves directly in front of the blindingly…

STARGAZER Christmas gift guide With the holiday season just around the corner, All About Space selects the space gifts sure to delight any fan of the universe Best for observers Meade Infinity 76 Cost: £129.99 (~€149.99/$165.00) From: currys.co.uk Introduce your loved ones to the wonders of the night sky with the Meade Infinity 76 – the straight-from-the-box, no-nonsense telescope designed to get astronomers of every age and ability stargazing in minutes. Budding astrophotographer? Perfect! Exclusively included with the Infinity 76 is Meade’s universal smartphone mount to snap and share all those stunning celestial views! Smooth tracking controls and a nifty red-dot finderscope help provide a limitless supply of stars, planets and other space objects to locate and discover, conveniently packing away within the signature Meade blue travel bag for astronomy…

Our contributors include… Giles Sparrow Space science writer Jupiter has a deadly secret in the form of Earth-destroying asteroids. Giles chats to the researchers on what this could mean for our future. Jonathan Fortney Astronomer Answering your questions about the universe this month, Jonathan is joined by astronomers from all over the world to reveal secrets of the cosmos. Matt Balme Planetary Scientist What can we learn from the winds of Mars? Matt uncovers how they're vital for ExoMars' role in finding out more about the Red Planet's past. James Romero Science writer James uncovers how caves in the Solar System could be essential in our future plans for manned space exploration as well as protecting colonies.…

A sight you 'knead' to see ©ALMA The ‘Cosmic Pretzel’ is the name coined for this image of two baby stars twisted and tangled in a pretzel-shaped string of filaments of gas and dust. The two stellar siblings were spotted in a small cluster of stars in the Barnard 59 dark nebula by the European Southern Observatory’s Atacama Large Millimeter/ submillimeter Array (ALMA) in Chile. This network of filaments is being perceived as a circumstellar disc, essentially the material stars digest as they grow. Each disc is similar in size to the asteroid belt in our Solar System, and the distance between the two stars is 28-times the distance between the Sun and Earth.…

Missing link: early dark energy There may be an exotic form of dark energy lurking in the universe, and it could explain a stubborn discrepancy in measurements of the universe's expansion rate. This so-called early dark energy might have existed in the universe’s infancy, then flickered out of existence soon after. That, in turn, would explain why expansion rates disagree. During the past two decades, scientists who study the universe's accelerating expansion have found two very different rates. The universes' first light — the cosmic microwave background radiation or CMB — suggests a lower rate for the expansion of space than do studies of supernovas and pulsating stars in the nearby universe. In other words, the universe seems to be expanding faster now than would be predicted by how it…

Dr Matt Balme DECIPHERING THE WINDS ON MARS Dr Matt Balme reveals how understanding Martian breezes and storms are vital for the upcoming ExoMars mission and teases some exciting details ahead of the 'life-hunting' spacecraft's launch next year Interviewed by Lee Cavendish © El Guanche What work are you involved in for the European Space Agency and the Russian space agency Roscosmos’ ExoMars mission? Well there’s a UK Space Agency grant which is to look at what we call ‘aeolian processes’. Aeolian is basically [a term used to describe] anything to do with the wind, and how the wind affects the surface. We're looking at sand ripples, wind erosion and how the surface has been eroded or modified by the wind. And we’re going to be doing that through my…

Meteor showers These fantastic shows of ‘falling stars’ occur all throughout the year. It is worth paying attention to the phase of the Moon as well as the peak of the shower, as visibility of the fainter meteors can be marred the more full and bright the Moon is. Quadrantids Dates.. 12 December to 12 January Peak .................................................... 4 January Max per hour.............................................. 120 Constellation...................................... Boötes Lyrids Dates.........................................16 to 25 April Peak ..........................................................22 April Max per hour..................................................18 Constellation.............................................. Lyra Eta Aquarids Dates............................19 April to 28 May Peak ...............................................................5 May Max per hour................................................40 Constellation................................. Aquarius Arietids Dates.......................... 14 April to 24 June Peak .............................................................7 June Max per hour................................................ 50 Constellation........................................... Aries Delta Aquarids Dates.......................12 July to 23 August Peak ...........................................................30 July Max per hour.................................................25 Constellation................................. Aquarius Perseids Dates.......................17 July to 24…

Q&A Rongmon Bordoloi, Assistant Professor of Physics at North Carolina State University What would happen if the Fermi Bubbles were close to Earth? The bubbles are manifested perpendicular to the plane of the Milky Way, so if we were closer to the bubbles, we would still not be inside the bubbles. But since we would be close to the bubbles, their angular size in the sky would be bigger than what it is now. They would also appear brighter in different wavelengths than now as we would be closer to them. Otherwise things would not change too much. What would happen if we sent a spacecraft towards them? The bubbles are comprised of hot relativistic plasma, with temperatures exceeding 100,000 to 1,000,000 degrees Kelvin. However, this plasma is very diffuse,…

Timings: First contact: Mercury’s disc will first touch the Sun at 12:36, and will be fully silhouetted against it just a minute or so later. At this time the Sun will already be low in the south, around 17 degrees above the horizon. Mid-transit: Mercury will have made it halfway across the Sun at 15:26. By this time the Sun will have dropped a lot lower in the sky, and will be only five degrees above the southwestern horizon. Sunset: The transit will be cut short for UK observers by sunset, which will occur around 16:15, so we will miss the last two hours of the event. The flatter your southwestern horizon is and the higher up you are, the longer you will be able to follow the transit. After…

Jargon buster Conjunction A conjunction is an alignment of objects at the same celestial longitude. The conjunction of the Moon and the planets is determined with reference to the Sun. A planet is in conjunction with the Sun when it and Earth are aligned on opposite sides of the Sun. Right Ascension (RA) Right Ascension is to the sky what longitude is to the surface of the Earth, corresponding to east and west directions. It is measured in hours, minutes and seconds since, as the Earth rotates on its axis, we see different parts of the sky throughout the night. Declination (Dec) This tells you how high an object will rise in the sky. Like Earth’s latitude, Dec measures north and south. It’s measured in degrees, arcminutes and arcseconds. There…

STARGAZER The Northern Hemisphere The constellations of autumn are slowly being pushed from the night sky by those of winter, offering a much wider observing range © ESO © NASA, ESA © ESA/Hubble and NASA Along with the planetary members of our Solar System making their way along the ecliptic, a display of deep-sky objects – including a selection of elliptical and spiral galaxies – are there for astronomers to enjoy. The stars of winter have started to make themselves known. Orion, Cetus, Canis Major and Taurus in particular make a dramatic entrance in the darker skies. The Andromeda Galaxy (M31) and its satellites are still easy prey for those with telescopes with at least a small aperture, while all-time favourite the Orion Nebula (M42) is easy to spot with…

Phantom energy vs dark energy Phantom energy is set to take us down a destructive route Dark energy dilutes during expansion If the universe expands with a constant energy density, dark energy should become diluted. But phantom energy gets more intense With phantom energy, the energy density is said to actually increase with time. Phantom energy causes fast growth The growing density would force the universe to expand at an ever-increasing speed. Phantom energy tears the universe apart Since the universe expands beyond a cosmological constant, it gravitationally unbinds objects. Dark matter won't take over Phantom energy, however, will eventually become so strong it'll dominate other forces.…

Phantom energy The cyclic universe How the universe may be dying and springing back to life forever more ©Nicholas Forder The idea that the universe has gone through a process of expansion and contraction over and over again is not new, but the cyclic universe model by Paul Steinhardt and Neil Turok is nevertheless intriguing. It involves the observable universe residing in a higher-dimensional void, colliding with a mirror version and unleashing huge amounts of energy and matter that then disperses. Following a recollision, the process begins again. Time and space are infinite. Another collision The branes collide once again and repeat the process. It means we would be in just one of many cycles and that the universe pre-dates each Big Bang. The big collision The model posits that…

INTERVIEW BIO Dr Matt Balme Balme is a senior lecturer at the Open University, based in the UK. His work is largely focused on planetary science, and more specifically planetary geomorphology. Understanding how natural processes can shape an extraterrestrial planet has made him the recipient of a UK Space Agency grant to understand how wind affects Mars, and in particular Oxia Planum – the landing site for the ExoMars programme’s Rosalind Franklin rover. His previous work for the ExoMars mission included landing site selection, but his suggestion – Aram Dorsum – finished third.…

Mercury Planet profile Mercury The minute world is arguably the least explored of the four terrestrial planets © NASA Mercury is a planet that has sculpted not only our scientific understanding over generations, but also our culture. Mercury has been mentioned in text dating as far back as the 2nd millennium BCE by the Sumerians, and the ancient namesake of the planet is the Roman messenger god, Mercury. Mercury is the smallest of all the planets in the Solar System and the closest planet to the Sun, but there is so much more to it. Mercury is so tiny compared to the other planets that you can actually fit around 23,500 Mercurys into Jupiter, and it is roughly 1,400 kilometres (870 miles) larger in diameter than the Moon. The small…

What these caves could be used for There are many reasons to investigate these off-world caves Natural shelter The subsurface network of lava tubes on Mars and the Moon can save mission time erecting shelters on the surface while also protecting astronauts from harmful radiation and micrometeorites constantly raining down. Finding life If life once existed on Mars, the evidence is likely to be underground. Periodic spikes in methane have been measured within the Martian atmosphere, which some astrobiologists have put forward as possible evidence of cave-dwelling, methane-producing microorganisms. Understand the history of Mars Current exploration of Martian geology is limited to surface layers and minor depths from rover drilling. Caves provide an opportunity to travel back millions or billions of years by reading the story preserved in lava tube…

The theories There are some competing theories about the source of the Fermi Bubbles Fermi Bubbles are associated with Sagittarius A* The most likely explanation for the Fermi Bubbles appears to be a rapid energetic event at the centre of the Milky Way which took place less than 10 million years ago. This theory is based on gamma ray, X-ray and radio studies, with further research suggesting that they were caused by the supermassive black hole Sagittarius A* creating the bubbles over a few million years. The bubbles were created by gradual star formation This theory argues that the Fermi Bubbles were created by more gradual star formation from stars around the galactic centre. This would have taken place over a period of a few hundred million to a billion…

ASK Space Our experts answer your questions © Tobias Roetsch PLANETS What’s the difference between a gas giant and an ice giant? At their hearts, gas giant and ice giant planets are not so different. Really, a gas giant is just an ice giant with a lot more gas! The way we think that giant planets form is that an initial ball of ice and rock – a protoplanet – forms within the solar nebula, the disc of gas – mostly hydrogen and helium – and solids around a young sun. Once the protoplanet reaches about ten-times the mass of the Earth, it starts to have enough gravity to accrete solar nebula gas down on top of it. This accretion makes the protoplanet more massive, with an even better ability…

How do I watch it? Transits of Mercury and Venus are fascinating to watch, but potentially extremely dangerous too: you’re trying to see a small black dot moving across the brilliant solar disc, so you can’t just swing your binoculars or telescope around to the Sun and take a look – do that and you risk poaching your eyeballs in your head. It really is that dangerous. Fortunately there are several totally safe ways of watching a transit, and if you follow them you won’t risk permanently damaging or even losing your eyesight altogether. The safest way is to find out if your local astronomical society is holding a ‘transit watch’ event. If they are you can go along to it and observe the transit through their equipment in total…

Naked eye targets Naked eye & binocular targets Winter is coming, and the night sky is full of bright stars and beautiful star clusters once more Hyades star cluster (Melotte 25) This v-shaped open star cluster represents the horns of Taurus the Bull. Under a dark sky your naked eye will see around half a dozen stars within it, but it actually contains almost 400. Bright-orange Aldebaran is not a cluster member, it just happens to lie along the same line of sight. Pleiades star cluster (Messier 45) One of the loveliest star clusters in the sky, the Pleiades is also known as the ‘Seven Sisters’ because its seven brightest stars can be seen with the naked eye, making a ‘mini Big Dipper’. It contains more than 500 stars, covering…

Your astrophotography Astroshots of the month Send your astrophotography images to space@spaceanswers.com for a chance to see them featured in All About Space Derek Finch West Sussex, UK “This is a 25-minute exposure of the night sky above Halnaker windmill near Chichester, West Sussex. I wanted to capture the motion of the stars around the celestial pole together with the stillness of the windmill’s sails. A low, near-full Moon on the night provided sufficient light to bring out the details of the windmill without glaring out the sky. ”I took this shot – that I have entitled, ‘As the windmills and the heavens turn’ – using my Canon EOS 30D combined with a Tokina AT-X PRO 12-24 F4 (IF) DX II lens. I took 50 exposures of 30 seconds each.”…

WORTH £795! WIN MEADE ETX-125 OBSERVER An astronomer needs the right tools, and this telescope is the perfect partner Do you want to marvel at the night sky but need the companionship of a computer to help show you around? Look no further. One of Meade’s masterpieces is waiting to be won. The ETX-125 Observer telescope flaunts a Maksutov-Cassegrain design, allowing for observations at a higher magnification to bring fantastic views of a vast range of objects, such as the planets, double stars, globular clusters and so much more. The 127-millimetre (five-inch) aperture and 1,900-millimetre (75-inch) focal length provide a focal ratio of f/15, which is perfect for high-power astrophotography. Along with its full-sized steel tripod, an EQ tilt plate and a database of over 30,000 celestial objects, there…

HEROES OF SPACE SPACE Giovanni Battista Riccioli An underrated astronomer of the 17th century, who was responsible for naming lunar features Some popular, well-known names in astronomy are Johannes Kepler and Nicolaus Copernicus, known because of their groundbreaking discoveries. However, a name often overlooked from the same era is Giovanni Battista Riccioli, who contributed hugely to astronomy and theology. Born on 17 April 1598 in Ferrara, Italy, Riccioli moulded himself into a revolutionary thinker, studying – and later teaching – philosophy and theology in Parma and Bologna, both in Italy. He became a Catholic priest in the Society of Jesus, also known as the Jesuit order, but his work in astronomy during such an influential time has been severely underappreciated. The pinnacle of his work came in 1651 with an…