The vast nuclear furnace that we know as the Sun is responsible for dictating the seasons, climate and characteristics of every planet in the Solar System.
At about 150 million kilometres (93 million miles) from Earth lies a giant incandescent ball of gas weighing in at almost 2,000 trillion trillion kilograms and emitting power equivalent to1 million times the annual power consumption of the United States in a single second. Since the dawn of Earth 4.6 billion years ago it has been the one ever-present object in the sky, basking our world and those around us in energy and light and providing the means through which environments, and ultimately life, can flourish. We see it every day and rely on its energy to keep our planet ticking, but what exactly is this giant nuclear reactor at the centre of the Solar System that we call the Sun?
Over 5 billion years ago a vast cloud of dust and gas was located where our Solar System is now. Inside this nebula something huge was happening; gravity was pulling together the debris, likely the remnants of another star going supernova, into one central mass. As the various metals and elements were brought together they began to fuse into an object at the heart of this nebula. This dense clump of matter, called a protostar, grew and grew in size until it reached a critical temperature due to friction, about 1 million degrees Celsius (1.8 million degrees Fahrenheit). At this point nuclear fusion kicked in and our Sun was born.
At the heart of the Sun, hydrogen atoms fused together to produce helium, releasing photons of light in the process that extended throughout the Solar System. Eventually the hydrogen and helium atoms began to fuse and form heavier elements such as carbon and oxygen, which in turn formed key components of the Solar System, including humans. To us, it’s the most important object in the sky. An observer watching from afar, however, would see no discerning qualities of our star that would make it stand out from any of the other hundreds of billions of stars in the Milky Way. In the grand scheme of things it’s a fairly typical star that pales in comparison to the size of others.
For instance Sirius, the brightest star in the night sky, is twice as massive as the Sun and 25 times more luminous while Arcturus, the fourth brightest object in the night sky is almost 26 times the size of our closest star.
The Sun is located at a mean distance of 150 million kilometres (93 million miles) from Earth, a distance known as one astronomical unit (1 AU). This giant nuclear furnace is composed mostly of ionized gas and drives the seasons, ocean currents, weather and climate on Earth. Over a million Earths could fit inside the Sun, which is itself held together by gravitational attraction, resulting in immense pressure and temperature at its core. In fact, the core reaches a temperature of about 15 million degrees Celsius (27 million degrees Fahrenheit), hot enough for thermonuclear fusion to take place. The intense physical process taking place in the Sun produces heat and light that radiates throughout the Solar System. It’s not a quick process, though; it takes more than 170,000 years for energy from the core to radiate outwards towards the outer layers of the Sun.
Our Sun is classified as a yellow dwarf star and these stars range in mass from about 80 per cent to 100 per cent the mass of the Sun, meaning our star is at the upper end of this group. There are also three further groups into which stars are classified: Population I, II and III. Our Sun is a Population I star, which denotes that it contains more heavy elements compared to other stars (although still accounting for no more than approximately 0.1 per cent of its total mass). Population III stars are those that formed at the start of the universe, possibly just a few hundred million years after the Big Bang, and they are made from pure hydrogen and helium. Although hypothesised, no such star has ever been found, as the majority of them exploded as supernovae in the early universe and led to the formation of Population I and II stars, the latter of which are older, less luminous and colder than the former.
By now you’re probably thinking our Sun is insignificant, but that’s anything but the case. Being our closest star, and the only one we can study with orbiting telescopes, it acts as one of the greatest laboratories available to mankind. Understanding the Sun allows us to apply our findings to research here on Earth, such as nuclear reactors, and our observations of distant stars.
Andromeda nebula – туманность Андромеды
Arcturus – Арктур (звезда)
coronal mass ejection (CME) – выброс корональной массы
debris – осколки, обломки
dense clump of matter– плотный сгусток вещества
facula – факел
furnace – очаг; печь
gravitational attraction – гравитационное притяжение
helium – гелий
hydrogen – водород
incandescent – раскаленный, накаленный добела
nebula (мн. nebulae, nebulas) – туманность
prominence – (солнечный) протуберанец
protostar – протозвезда
remnant – след, остаток
spicule – спикула (на Солнце)
sunspot – солнечное пятно
supernova (мн. supernovae, supernovas) – сверхновая звезда
supernova explosion – взрыв сверхновой (звезды)
thermonuclear fusion – термоядерный синтез
On June 28, SpaceX attempted what was to be the company’s seventh resupply mission to the International Space Station (ISS), only to have the unmanned vehicle break up just over two minutes after launch, resulting in total mission failure, the company’s first. In a statement July 20, Elon Musk, SpaceX’s CEO, attributed the Falcon 9 rocket’s breakup to a strut that failed to meet force requirements, resulting in an overpressure event in the second-stage oxygen tank, though he declined to name the outside manufacturer and labeled this “an initial assessment.”
Six previous resupply missions had gone smoothly for the private space firm. On May 6, SpaceX also successfully tested its launch abort system – a sort of ejector seat for future crew. Additionally, the June 28 launch was meant to be the third attempt to land Falcon 9 on a drone barge – a bonus but so far unsuccessful objective – after launching the Dragon supply ship into orbit. While the rocket hit its target accurately on two previous landing attempts, it has been unable to land gently or upright enough to avoid destruction. SpaceX is striving for reusable rockets in order to drastically cut costs on future space launch missions. Unfortunately, the SpaceX ISS resupply failure was the third such in eight months, starting with Orbital Sciences Corporation’s Antares rocket malfunction last October and the Russian loss of its Progress capsule in April. The ISS still had supplies for several months, and further resupply missions occurred in July and August. Furthermore, several successful missions docked with the ISS in between the recent failures, including several SpaceX flights.
Астероид, черная дыра, созвездие, полумесяц, полнолуние, солнечное затмение, лунное затмение, комета, световой год, Млечный Путь, северное сияние, красный гигант, желтый карлик, сила притяжения, ось Земли.
The visible surface of the Sun, ..., has a temperature of 5,530°C (9,980°F) and is made mostly of convection cells, giving it a granulated appearance. Most of the Sun’s ... is generated in the inner core, which extends outwards from the centre to about a quarter of ... .
... is a thin layer about 2,000km (1,240 miles) thick, that sits just above the photosphere and is the area where ... are visible.... is the outer ‘atmosphere’ of the Sun. It is made of plasma, extends millions of kilometres outwards and has a higher temperature than the inner photosphere. ... is the area full of electromagnetic radiation from the core that bounces around as photon waves. It makes up about 45 per cent of the Sun.
Солнечная система – планетная система, включающая в себя центральную звезду – Солнце – и все естественные космические объекты, обращающиеся вокруг Солнца. Она сформировалась путем гравитационного сжатия газопылевого облака примерно 4,57 млрд лет назад.
Большая часть массы объектов Солнечной системы приходится на Солнце; остальная часть содержится в восьми относительно уединенных планетах, имеющих почти круговые орбиты и располагающихся в пределах почти плоского диска – плоскости эклиптики.
Четыре меньшие внутренние планеты – Меркурий, Венера, Земля и Марс (также называемые планетами земной группы) – состоят в основном из силикатов и металлов. Четыре внешние планеты – Юпитер, Сатурн, Уран и Нептун (также называемые газовыми гигантами) – намного более массивны, чем планеты земной группы. Крупнейшие планеты Солнечной системы, Юпитер и Сатурн, состоят главным образом из водорода и гелия; внешние, меньшие Уран и Нептун, помимо водорода и гелия, содержат в составе своих атмосфер метан и угарный газ. Такие планеты выделяются в отдельный класс «ледяных гигантов». Шесть планет из восьми и три карликовые планеты имеют естественные спутники. Каждая из внешних планет окружена кольцами пыли и других частиц.
В Солнечной системе существуют две области, заполненные малыми телами. Пояс астероидов, находящийся между Марсом и Юпитером, схож по составу с планетами земной группы, поскольку состоит из силикатов и металлов.
Our local star might seem to be an unchanging ball of blazing light, but in reality its upper layers are seething with extreme activity that varies in a period of around 11 years, and whose influence reaches as far as Earth.
The Sun is a very special star, not only because the life on Earth depends on it, but because the Sun is the only star that we can observe in detail. What makes the Sun (and other active stars) very interesting is the presence of a magnetic field. One of the great challenges in solar physics is to understand, and ultimately predict, solar magnetic activity.
The Sun is the dominant force shaping conditions on Earth and throughout our Solar System – a brilliant ball of gas powered by nuclear fusion in its core, whose influence reaches out across billions of kilometres. Radiation at both visible and invisible wavelengths provides heat and light to the planets, and from the point of view of a casual observer, seems more or less constant – certainly seasonal changes as a planet moves around its orbit and changes its orientation and distance from the Sun have a far greater influence over its climate than any slight fluctuations in the Sun’s behaviour.
But nevertheless, these changes are real – and while they do little to change the Sun’s heating effect on Earth, they can be spectacularly violent in other ways, threatening orbiting satellites, distant space probes and even reaching down to the surface of the Earth itself. The Sun is unpredictable and can produce extreme outbursts at any time, but in general, the frequency and intensity of these events varies in a ‘solar cycle’ of around 11 years. The cycle, as we shall see, is fundamentally driven by the Sun’s changing magnetic field and, through improving their understanding of it, astronomers hope to learn more about the deep structure of all stars.
While it may appear superficially solid, the Sun’s visible surface, or photosphere, is in fact a layer a few hundred kilometers deep marking the region where the Sun’s gases finally become transparent and allow light and other radiations to escape into space – temperatures in this region average approximately 5,500 degrees Celsius (9,930 degrees Fahrenheit), but sunspot regions are up to 2,000 degrees Celsius (3,630 degrees Fahrenheit) cooler, and so appear dark in comparison.
Sunspots are regions of strong magnetic fields that appear dark when the Sun is observed in visible light. At solar maximum sunspots are more numerous than at solar minimum. Larger and more complex sunspots are more commonly seen near solar maximum. But while you might think that dark spots on the Sun’s surface would cause its overall energy output to fall, the opposite is actually the case: The Sun’s radiative output peaks at solar maximum. This seems counter-intuitive, but sunspots are surrounded by bright features called faculae and plages that make the Sun brighter at solar maximum.
While sunspot activity is by far the most obvious indication of the solar cycle at work, it is far from being the only one. Since the beginning of the space age, new technologies for studying the Sun at invisible, high-energy wavelengths such as the ultraviolet and X-rays have revealed far more spectacular outbursts that are also linked to the cycle. The magnitude of the solar radiative variation over a solar cycle is a function of wavelength. In visible light, the change is very small, but it is much larger in the shorter wavelengths of ultraviolet and X-ray radiation. Much of this higher-energy radiation is associated with solar flares – sudden brightenings of the Sun’s surface that typically last for just a few minutes but can release enormous amounts of energy – equivalent to a billion megatons of TNT. They occur in the solar corona – the Sun’s thin outer atmosphere where gas is far more tenuous than at the photosphere, but temperatures can soar up to 2 million degrees Celsius (3.6 million degrees Fahrenheit), and are often seen above active sunspot regions. Flares, too, are thought to be connected to changes in the Sun’s magnetic field, specifically ‘reconnection events’ in which a loop of magnetic field arcing high into the corona ‘short-circuits’ at a lower level to release an enormous amount of energy and a burst of high-energy radiation. Flares are also often associated with huge releases of high-speed subatomic particles known as coronal mass ejections (CMEs). Travelling at millions of kilometres per hour, the particles from a CME can reach Earth within a couple of days.
A direct hit by a powerful CME can cause significant disruption to our planet’s magnetic field. This kind of event, known as a geomagnetic storm, can send particles pouring into Earth’s upper atmosphere where they cause stunning displays of aurorae (northern and southern lights). However, the combination of high-energy radiation and energetic particles can also have more serious effects for modern civilisation, affecting orbiting spacecraft and even ground-based power networks.
Perhaps the most famous geomagnetic storm is the ‘Carrington Event’ of 1859, associated with a brilliant flare first spotted by English astronomer Richard Carrington on 1 September 1859. The ensuing coronal mass ejection, travelling at tremendous speed, reached the Earth barely a day later, triggering northern lights that were visible as far south as the Caribbean, and bright enough for people at higher latitudes to read newspapers in the middle of the night. As the Earth’s magnetic field warped under the onslaught, telegraph systems around the world went haywire as they were overloaded with unexpected electric currents.
While both flares and CMEs can occur throughout the solar cycle, frequency and average strength rises significantly around the solar maximum (the Carrington Event, for instance, is acknowledged as the peak of ‘Solar Cycle 10’). Despite the energies involved, the total solar irradiance (TSI) – the amount of solar radiative energy that reaches the Earth’s upper atmosphere – varies by just 0.1 per cent over a solar cycle, but recent research has shown that within this overall pattern, solar output at different wavelengths can vary by much greater amounts.
One thing is for certain, however – the Sun and its various cycles will continue to influence everything from technology to climate. We can do nothing to influence our local star, so we must learn to at least understand it more accurately, and be prepared for its occasional outbursts of violence.
Через несколько миллиардов лет Солнце станет «красным гигантом», настолько большим, что оно поглотит нашу планету. Однако непригодной для жизни Земля окажется гораздо раньше, чем это произойдет. Примерно через миллиард лет тепло, исходящее от Солнца, вскипятит океаны.
На сегодняшний день ученые классифицируют Солнце как звезду главной последовательности. Это означает, что оно находится на самом стабильном этапе своей жизни. В этот период водород, который находится в его ядре, преобразовывается в гелий. У звезды такого размера данная фаза длится чуть более 8 миллиардов лет. Возраст нашей Солнечной системы составляет немногим больше 4,5 миллиардов лет. Это значит, что Солнце лишь на половине своей стабильной фазы.
По истечению 8 миллиардов лет размеренная жизнь Солнца станет активнее. Причиной таких изменений послужит тот факт, что в ядре закончится водород – весь он превратится в гелий. Проблема заключается в том, что ядро Солнца недостаточно горячее для того, чтобы сжигать гелий.
Гравитационная сила звезды толкает все газы в сторону центра. Пока в ядре имеется водород, он сжигается в гелий. В результате этого создается внешнее давление, достаточное для того, чтобы уравновесить гравитационное притяжение. Но когда в ядре звезды не останется водорода, гравитационная сила одержит верх. В конце концов она сожмет центр звезды до такой степени, что начнется горение водорода в оболочке вокруг мертвого ядра, наполненного гелием. Как только Солнце начнет сжигать больше водорода, оно будет считаться «красным гигантом».
Но почему же «красный гигант»? Процесс сжатия в центре позволит расшириться внешней области звезды. Горение водорода в оболочке вокруг ядра значительно увеличит яркость Солнца. Из-за увеличения размера звезды поверхность остынет и изменит цвет из белого в красный. Из-за того, что такие звезды увеличиваются в размере, становятся ярче и краснее, их принято называть «красными гигантами».
Понятно, что Земля как планета не выживет в условиях таких изменений солнечной активности. Увеличенная поверхность Солнца, вероятно, достигнет орбиты Марса. Несмотря на то, что земная орбита также предположительно расширится, этого будет недостаточно для того, чтобы Земля могла устоять перед воздействием «красного гиганта». Наша планета начнет быстро разрушаться.
Прежде чем Земля будет окончательно разрушена, жизнь столкнется с рядом непреодолимых препятствий. Это произойдет еще до того, как закончится горение водорода. Каждый миллиард лет яркость Солнца увеличивается на 10 %. Это означает, что с течением времени на нашей планете становится теплее. По мере того как Земля будет нагреваться, вода на ее поверхности начнет испаряться.
Увеличение яркости Солнца на 10 % в сравнении с текущим показателем кажется не таким уж существенным изменением. В действительности же последствия этого будут катастрофическими для нашей планеты. Такое увеличение яркости Солнца будет достаточным для того, чтобы изменить расположение зоны обитаемости вокруг звезды. Под обитаемой зоной понимается условная область в космическом пространстве, где вода может стабильно существовать в жидкой фазе.
ALMA peered into the early universe, only a billion years after the Big Bang, to find the elusive signature of ionized carbon in early galaxies. Carbon likes to bond with other elements, so seeing carbon on its own in an ionized (highly energized) state is a strong sign that astronomers are looking at unevolved young galaxies that have not had time to form complex molecules. The new information, published June 25 in Nature, sheds light on how the early universe evolved.
Scientists using data from the Mars Reconnaissance Orbiter identified glass deposits around ancient craters on the Red Planet. The researchers, writing in Geology’s June issue, point out that on Earth impact glass can preserve valuable biosignatures from earlier eras, and the same could be true on Mars. That makes these glassy deposits prime targets for future sample exploration missions.
Astronomers using the Chandra X-ray Observatory pinpointed the location of a neutron star system called Circinus X-1. The star is embedded in a thick shroud of gas and dust, obscuring the source. But, as reported in the June 20 issue of The Astrophysical Journal, scientists combined the different arrival times of X-rays echoing off these clouds with detailed radio images to home in on a distance of 30,700 light-years to the star.
Three-quarters of a billion years ago, our “sister planet” globally resurfaced. Venus is unmistakable in our sky. Never straying terribly far from the Sun, it blazes brilliantly either in the evening or morning. But along with its brilliance, Venus hides a secret.
Many inner planets and moons preserve a great record of ancient impacts from objects that struck them in the early history of the solar system, right on down to the present. But planetary scientists have found that Venus underwent a colossal resurfacing event, a volcanic cataclysm, some three-quarters of a billion years ago. This means that most of the craters and other surface features we find on Venus are relatively young. But what could have caused such a huge, relatively recent global resurfacing? As one planetary scientist put it, “We are in the unenviable place of having to explain a planet that inexplicably threw up all over itself!”
For as yet unknown reasons, Venus seems to have stored enormous amounts of energy deep inside for a long time after the planet’s formation. Scientists know that the better part of a billion years ago, a huge amount of this banked energy was released. But no one yet knows what triggered this event or why it happened exactly when it did.
Instabilities deep within Venus conspired – through physical evolution, the laws of physics, and interplay between countless atoms – to let loose and recover our “sister planet” in a large way.
In the 1990s, NASA undertook an initiative called Mission to Planet Earth. The program would take the remote sensing techniques used to explore other planets and turn them on our home world. The plan virtually screamed “practical benefits.”
By any measure, NASA’s Earth science program has been an extraordinary success. It has revolutionized weather forecasts, agricultural predictions, resource management, and climate science. Return on investment is off the charts. But such a program has to be maintained. Quoting a 2007 report from the National Academy of Sciences, “The current capability to observe Earth from space is in jeopardy.” Without resources, that capability will be lost.
So why is it that as of this writing, Congress is poised to slash as much as three-quarters of a billion dollars from the program and cripple a vital global perspective that we have come to depend on? The answer is disturbingly simple. Many in Congress, along with their well-heeled backers, would prefer that we not see what NASA’s data are showing us.
The crux of the issue is, of course, global warming. But one thing that you won’t often hear amid the hype on cable news is a calm, rational explanation of what global warming is and how it works.
Imagine a rock adrift in space. Energy arrives as visible sunlight, trying to heat things up. Energy leaves as thermal infrared radiation, trying to cool things down. At some temperature, the two will balance. Voilà! Now imagine the rock is wrapped in a blanket that lets sunlight in but makes it harder for infrared to get out. More energy is coming in than is leaving, so things heat up. Eventually, balance is restored, but at a new higher temperature.
The atmospheres of Venus, Earth, and Mars are just such blankets. Gases like carbon dioxide, water vapor, and methane are transparent to visible sunlight but block escaping infrared. The thin atmosphere of Mars only raises the temperature by about 9° F (5° C). The massive atmosphere of Venus heats the surface to a whopping 860° F (460° C), well above the melting point of lead!
Earth is the Goldilocks world. The so-called greenhouse effect raises Earth’s average temperature from 33° F (18° C) below the freezing point of water to 27° F (15° C) above the freezing point of water.
Since 1750, humans have released over 300 billion metric tons of carbon into the atmosphere. There is 44 percent more carbon dioxide in our atmosphere today than there was before the Industrial Revolution. Half of that increase has come since 1980. There is over 30 percent more atmospheric carbon dioxide than at any time in the last 800,000 years. And just as our student realized, when you crank up the thermostat, things will start to heat up.
There are about a half dozen ways to measure Earth’s thermal imbalance, and they all show that the planet is warming. Imagine Earth’s surface covered by 1-kilowatt heaters, one every 100 feet (30 meters) or so. The heaters run 24/7, year after year, decade after decade: That is global warming.
While the details are subtle, the basics of global warming are incontrovertible and easily understood. It is disingenuous and irresponsible to pretend otherwise. Politicizing climate change is like politicizing gravity. If you step off of a building, you fall and hurt yourself, regardless of your politics. Crippling NASA’s ability to observe Earth will not stop global warming; it will only leave us blind.