Innholdsfortegnelse for Beginners Guide to Astronomy i Beginners Guide to Astronomy

So, kilometres or miles are confined to the Solar System. We could use something better, but we’re safe and happy with them and there’s some continuity with how we do things on Earth without getting too space-ified too early on. The other ‘something better’ is simply a unit based on Earth’s mean distance from the Sun – instead of it being 150 million km we can say it is one astronomical unit or 1 AU. Using this method, all the planets, and anything else flying around the Sun (or Earth) can be defined in terms of an astronomical unit. For example, Jupiter is about 5 AU from the Sun; that’s five times farther from the Sun than Earth. Travelling out farther, the nearest star, Proxima Centauri, is around 268,000 AU…

When you start your stargazing quest, you need do nothing more than walk outside on a clear night and look up. But there’ll come a time when you feel you need to get closer to the view – it happens to us all! And for this you’ll need a pair of binoculars or a telescope. These pieces of optical equipment do two things: firstly they collect more light from the dim and distant stars than your eyes alone do, and secondly they magnify the view. In this section, we’ll take you through the best types of equipment to train on the night skies. We’ll look at why it’s best to begin with binoculars before moving on to a telescope, and why the mount that a telescope tube sits on is…

When you’re out stargazing, the field of view is the amount of sky that you can see at any one time. It varies depending on what equipment you’re using – here we show you how the appearance of the constellation of Cassiopeia changes when you look through different types of instrument. BINOCULARS Using a standard pair of 10x50 binoculars you instantly increase your magnification to 10x, meaning things look 10 times bigger. Also, instead of the standard 5-7mm width of your pupils, you have the binocular’s 50mm-diameter lenses to collect starlight. This allows you to see faint stars deep into mag. +10.0 territory. Depending on the make, 10x50 binoculars have a field of view between 5º and 9º. This gives you lovely wide views to sweep across the sky in…

Digital photography has made taking pictures of celestial objects much easier. In days gone by, you needed all manner of telescope-mounting regalia for your camera, and then had to get the camera’s film processed before you could see your pictures. Then the CCD (charge-coupled device) camera arrived on the scene. A CCD is an electronic light sensor that’s used in digital cameras. At first, only astro-imaging experts used them because CCDs came in big, heavy cameras with complicated controls and were expensive. But the era of digitally imaging the heavens had arrived. Pretty soon the CCD and its electronic-lightsensor cousin the CMOS (complementary metaloxide- semiconductor) chip found their way into a smaller, lighter, friendlier package called the webcam. These were cheap and simple to use, so it’s not surprising that…

After the invention of the telescope in the early 17th century, the true nature of the night sky became apparent for the first time. What had been mere fuzzy blobs as seen by the unaided eye now had form, and suddenly a whole new world of nebulae, galaxies and star clusters could be observed. When those first telescopes were trained on the stars, an interesting discovery was made: that not all the stars we see as single points of light with our eyes are, in fact, alone. Some were revealed to be two stars or maybe even more. Double stars and multiple star systems were discovered. As the number of double stars being found grew, it became necessary to divide the category up further, in order to clarify exactly what…

Some astronomers seem to get a complex about the Moon. It’s not that they’re affected by it in werewolfish ways, but rather they develop a loathing for our large, rocky satellite. Why? Well, these usually friendly astronomers come to see it as a natural light polluter, washing away all the faint, small and fuzzy galaxies and nebulae they like to view. To them, the Moon is more of a nuisance than an object that’s worthy of observing. This is a real shame as the Moon has so much to offer. There’s simply no truth in the assertion that when ‘you’ve seen it once, you’ve seen it all’ – with binoculars and small telescopes the appearance of the Moon can change dramatically from one hour to the next. Another reason it’s…

Stars are fascinating things: at the simplest level they make the patterns of the constellations. Some brighter examples give hints of colour, like red Betelgeuse in Orion. The trouble is, every night-time example is so incredibly far away. Fortunately, the Sun is one star that’s right on our doorstep and it’s available for everyone to look at, understand and, depending on how you’re looking at it, gasp in amazement The Sun, our source of natural light and warmth, and the star that made life possible on our planet, is just next door in astronomical terms. On average, it’s only 150 million kilometres away. However, the Sun’s close proximity makes it brighter and hotter than any other star in the sky. Never look at the Sun using just your eyes, unfiltered…

Look up at the Moon at certain times of the year and you’ll be able to witness the motion of the Solar System on a truly grand scale. There’s nothing quite like watching a lunar eclipse as the Sun, Earth and Moon become perfectly aligned. There are three types of lunar eclipse, the most exciting of which is a total lunar eclipse. The other two types are partial and penumbral lunar eclipses, which we’ll come to later. Total lunar eclipses can only happen at full Moon when the Sun, Earth and Moon are lined up in space. However, most months the Moon moves above or below Earth’s shadow, which is why eclipses don’t happen every time the Moon is full. They occur when the Moon travels into Earth’s shadow during…

Right now, out there in the Solar System, millions of tiny bits of rock are flying around. They all go unnoticed, until our planet gets in their path. These particles, which can be as small as a grain of sand, travel at such a high speed that they burn and glow as they shoot through the upper atmosphere. And if they’re large enough, they may even make it down to the ground. In astro-speak, these bits of rock have three different names depending on where they are. When they’re in space they’re meteoroids; once they’re in the atmosphere and we see them racing across the night sky they become meteors; and if any of them reach the ground without burning up, they are known as meteorites. At this point it’s…

Our Galaxy, the Milky Way, is one of the most magical sights of the night. Away from light-polluted regions our Galaxy looks like a river of light. It becomes clearly visible every year as autumn approaches, the brightest part of it adorning our skies The term Milky Way can refer to several different objects, as well as a famous chocolate bar. Some use it to refer to the weaving band of light crossing the sky, created by the hundreds of thousands of faint, distant stars whose light combines to form this wonderful feature. However, there’s much more to our Galaxy than these stars, which are just the visible part of it. The term Milky Way is also used to describe our entire Galaxy, a huge island of stars of which…

Before the dawn of the telescope, only exceptionally bright objects were visible to those looking skywards. They only hinted at the wide variety of different objects lurking in the depths of our Universe: the so-called deep-sky objects In the old days they all went by the Latin name of nebulae, or ‘little mists’ in English, simply because they all looked like small, light, fuzzy, foggy patches in the otherwise black night. Once telescopes became more powerful, it became clear that not all nebulae were the same. Astronomers became aware that there were objects as varied as galaxies, globular clusters and supernova remnants. The term ‘nebula’ became narrower, being used to describe deep-sky objects made up of huge clouds of dust and gas many lightyears across. This doesn’t make nebulae any…

For budding and seasoned stargazers in the northern hemisphere, the Messier Catalogue is the most famous observing list of astronomical deep-sky objects. Within the 110-strong catalogue are examples of every known deepsky object – a good assortment of galaxies, open and globular star clusters, nebulae and one supernova remnant. This is the famous Crab Nebula in Taurus, which is also the first object in the catalogue. It bears the designation Messier 1, commonly written as M1. The Messier Catalogue has become so ingrained into astronomical lore that objects are commonly described by their Messier number. So ‘M42’ is often used in place of, or in addition to, the actual name of this object, which is the Orion Nebula. The irony of this useful catalogue is that it was never intended…

On so many levels, the Andromeda Galaxy is a marvel. Don’t be fooled by its deceptively ordinary designation of ‘M31’, given to it by Charles Messier in his 1781 catalogue of astronomical objects. The more you delve, the more fascinating Andromeda becomes. Autumn is the best time of year to see the Andromeda Galaxy: it’s at its highest in the south at about 8pm. As soon as it gets dark, you can be sure that M31 will already be pretty high. To your naked eye it will look like a fuzzy patch. From urban locations, the galaxy is equally visible in binoculars, even if you have a fair amount of light pollution. But dark, Moonless skies will give you the best views. Knowing a bit about this fuzzy patch of…

JARGON BUSTER • ASTERISM A pattern of bright stars that can be easily found again and again. Famous asterisms include the Plough, the Summer Triangle and Orion’s Belt. • DOUBLE STAR Two stars that appear very close together. They may actually be orbiting each other, in which case they are known as a binary double, or they can simply appear to be close because of our viewpoint in space, in which case they are known as an optical double. • STAR COLOURS Stars can be different colours depending on the amount of gas they are made of and how far through their lives they are. FINDING YOUR WAY FROM THE PLOUGH The Plough doesn’t just help you to find Polaris. Here are four more stars, and their constellations, that the…

We take it for granted that Earth is spinning and travels around the Sun. We have to, because there is no way any of us can feel the spin or the speed of movement of our planet as it travels through space. Cast your mind back to when you were seven years old. You’ve been told that the reason the Sun crosses the sky is because Earth is turning on its axis once a day. And before you’ve had time to take this in you’re informed that Earth takes a year to travel round the Sun. Then, after primary school, you’re introduced to some numbers. For instance, the average speed of Earth through space (following its orbit) is just under 30km/s, which is nearly 108,000km/h (67,000mph). And the rotation of…

Today’s modern telescopes make it easy for you to whizz through your Go-To list of deep-sky wonders in no time at all. You might think that the idea of actually stopping on an object for 15 minutes or so, especially to draw the thing or at least be able to describe it in detail, seems a little old-fashioned. If this is the way you practise astronomy, then you can certainly say that you’ve seen any given object – but you haven’t truly ‘observed’ it. To fully appreciate the sky, there is nothing like an observing log – a journal in which you detail information, observations and thoughts during an observing session. There are many reasons to keep a log, as you’ll see from the case studies below, including Patrick Moore…

So now you know all about distances in space, and how our Earthly metres and feet are not much use, as they turn into impractically large numbers with lots of zeroes, like 56,000,000,000,000,000,000km – that’s 56 quintillion km. Now, a ‘quintillion’ doesn’t mean anything to me; add on a few squillions and it’s all uncharted territory. You know that to make life easier when measuring distances across the Solar System, we use the astronomical unit (AU), which is the mean Earth to Sun distance. And, for the next stage (all the way to the ‘edge’ of the Universe, in fact) we use the lightyear. One lightyear is, of course, simply the distance that light travels in one year. That’s all well and good, but the missing ingredient is how do…

In Part 1, we looked at setting up an equatorial mount so it would be a solid and stable platform for holding your telescope. Now we’re going to explain how to make the mount follow, or track, stars and other objects as they move with the sky as the night hours tick by To do this properly, the equatorial mount has to be ‘polar aligned’; its right ascension (RA) or polar axis must be lined up so that it points at the north celestial pole. This is the point that the sky appears to rotate around. It’s a notional spot that denotes the point at which our planet’s axis of rotation meets celestial sphere, that imaginary ball with the Earth at its centre, onto whose inner surface all the stars…

COATINGS As light passes through the lenses in your eyepiece, a little bit of it is taken away. To minimise this loss of light, manufacturers coat the lenses with substances like magnesium or calcium fluoride. The best eyepieces will be the ones that say they are ‘fully multi-coated’, though ‘multi-coated’ eyepieces are still good. Try to avoid eyepieces that are described as ‘fully coated’ or just ‘coated’. One way to test the coatings is to fix a black cap on the bottom of your eyepiece and look down the barrel in daylight. The darker the glass looks, the less light is lost and the better the eyepiece. The importance of eyepieces took me a long time to realise. To say they can make or break you as an amateur astronomer…

Your telescope is the piece of kit that everyone admires. Your friends will look through it and the wonders of the Universe will be revealed to them. What they probably don’t give a thought to, though, is the variety of accessories that enable the entire observing process to go as smoothly as it does. When we talk about accessories we don’t just mean nice toys, either. We’re talking really useful bits of equipment that will help you get the best out of your telescope. ESSENTIAL KIT First on the list come finderscopes – these are invaluable for finding objects. Many smaller scopes come with a basic 5x24 finder, which means a 24mm lens with 5x magnification. But there are many upgrade options, and even moving up to a 6x30 version…

When you gaze up at the night sky, it looks like a lot of stars are on their own. But a solitarylooking star may be a member of a vast group that’s travelling through space as a unit. If we wind the clock back millions of years, we may find the stars of one of these families forming in the same vast cloud of dust and gas, known as a nebula. Known as open clusters, these families of anywhere from a few dozen to a few thousand stars are created in the dusty spiral arms of our Galaxy. They travel together through space, but gentle tidal forces eventually cause the stars to move apart until they begin to merge into the general starry background. There are many fine examples of…

SUNSPOTS These features usually appear in pairs and are caused by magnetism, which draws away energy. Their resulting lower temperature makes these regions appear dark. LIMB DARKENING The photosphere is translucent, so when you look at its centre you’re peering deep into the hotter, brighter part. This is why it appears lighter than it does at the edges. PHOTOSPHERE The light from the Sun is given off here. Its temperature is around 6,000ºC and it is home to sunspots. PROMINENCES These are concentrations of gas, associated with sunspots, that move up from the chromosphere. In just an hour, active prominences can shoot to heights of 750,000km. FILAMENTS A filament is the same as a prominence, except that whereas prominences are seen outside the Sun’s disc, filaments are seen against the…

PLANETS IN MOTION DAY The time it takes for a planet to spin once on its axis relative to another object. For Earth, relative to the Sun, the day is 24 hours long. But relative to the stars it’s 23 hours 56 minutes and 4 seconds because the Sun moves against this fixed background. ORBIT A planet’s orbit is the circular or elliptical path it makes around the Sun. YEAR The time it takes for a planet to orbit once around the Sun. One year for Venus is 224.7 Earth days, while one year for Neptune is 164.8 Earth years. Out there in space is a pretty average star about halfway through its life, shining away with a nice even temperament – our Sun. I can say all this because,…

The Solar System is truly an incredible place, but one world in particular stands out and truly deserves the title King of the Planets: Jupiter. It is grandiose in all respects. Not only is it the largest of the planets – it would take 1,321 Earths to fill the volume of Jupiter – it’s also more than likely that it keeps the largest entourage of moon It’s the massive gravitational effect of Jupiter that does the trick, attracting more than 100 moons into orbit around the planet at the latest estimate. Many of these satellites are fairly small and can’t be observed from Earth, but the biggest four are easy to spot with just a small pair of binoculars. A minimum size pair for spotting these four moons would be…

We live in an age of high-tech telescopes and computer modelling, so there’s something curiously reassuring about the way comets continue to do their own thing, regardless of what any experts say that they should be doing. It’s this unpredictability that makes any cometary apparition a unique event. Will the comet be bright? How long will its tail be? The only thing you need to do to find out the answer is to take a look into the night sky, so long as you know when to do it. Thankfully, with the help of the internet, you can keep right up to date with the latest discoveries, as well as predicted viewing opportunities and magnitudes. This is exactly what many of us did during December 2006 and January 2007 with…

Who would have thought that a silver ball could change the world? That’s what Sputnik 1 did on 4 October 1957. Not only did it start the Space Race between the former USSR and the USA, which led to man walking on the Moon, but it also paved the way for the technological advances that we take for granted today. The advances that led to accurate weather forecasts, which can predict the course of a hurricane, and the global positioning system (GPS), used to pinpoint those in danger, all owe a great debt to the technology that followed Sputnik 1 into orbit around our planet. Sputnik orbited for three months before reentering Earth’s atmosphere and burning up. In its wake the number of satellites sent up grew. Today thare are…

Our position inside the Galaxy allows us to see the stars that make up the other arms of the Milky Way as a band arcing across the heavens. But since we’re well away from the centre of the Galaxy, the arc isn’t evenly spread around the sky. If we look in the direction of the constellations of Orion and Monoceros, we are looking out of our Galaxy’s plane into empty space. This means that in the UK the dark nights of late winter and early spring are not the best time to see the Milky Way. However, in the opposite direction, towards Sagittarius and Scorpius, we are looking directly into the teeming centre of our Galaxy. More dust, more gas and more stars create a river of light here, making…

Stars are seemingly steady, inactive things in the night sky. They shine away, puncturing the blackness of the night like silent, benign candles. In reality, each and every one is an amazingly extreme object. A star lives its life ferociously, creating energy to hold itself in balance against the phenomenal force of gravity acting upon it. For most stars this works tremendously well – until the fuel runs out. For massive stars that are nine to 10 times the size of the Sun, the end is inevitable: it comes as a supernova, a cataclysmic explosion in which most of the star’s matter is blasted out into space, with a vast increase in brightness that can last from weeks to months. The exact story of a supernova involves several stages. A…

USING CHARTS If you’re looking for the star Deneb on a chart, you can find it with the following coordinates: Right ascension (RA) 20h 41m 25.9s Declination (Dec.) +45° 16’ 49” Clearly, this is not all just nice simple degrees. In declination the ‘ symbol represents angular (or arc) minutes and the “ represents angular (or arc) seconds. A degree is a pretty large unit on the sky – two widths of the full Moon, in fact! So, 1° is divided into 60 arcminutes and each arcminute has 60 arcseconds – used for super accuracy or very small things. The + or – at the start shows whether it is in the northern (+) or southern hemisphere (–). Right ascension is written as hours, minutes and seconds – as in…

HOW FAR ARE STARS? For measuring the big distances to the stars, astronomers use something called parallax. This involves watching a close star’s movement against the fixed background of much more distant stars. It’s like holding up your index finger at arms‘ length and viewing it against the background through your left eye and then your right – there is a position shift between each view because your finger is much closer than the background. This is how it works in space, too, except our two views are six months apart, when Earth is on either side of its orbit around the Sun. This is the widest possible separation we can get between our telescopic ‘eyes’, and even then the shifts are so small that this technique only works accurately…

Imagine a very big rubber band, as wide as a road and as long as you fancy. Onto this rubber band, at some distance apart, place two cars. Now with two helpers at each end of the band, start to pull. You can envisage what will start to happen: the fabric of the band will start to stretch. What’s happening to the cars? They are beginning to move apart, not because they themselves are moving, but because the rubber between them is stretching. This is exactly what happens in space, on a much larger scale. We see galaxies appearing to move away from us, when in reality it is the space in-between stretching. This has an effect on the light we get from the distant galaxy – it is being…

Putting your telescope on an equatorial mount enables you to follow stars as they continue their steady progress across the night sky. The mount may look complex, but it really doesn’t take long to master. Over the next six pages, we’re breaking down everything about these mounts into easy-to-follow steps, starting with putting them together. We’re using an EQ3 mount, but the techniques will work for other types, too. MOUNT HEAD An equatorial mount is made up of a tripod and a mount head, which holds the telescope and moves it about on two axes, one called right ascension (RA) and the other called declination (Dec.)…

In the first two parts of this guide to equatorial amounts, we’ve looked at how to set up your mount so that it will do its job properly, making it easy to find and follow objects out there in space. A star, planet or nebula can be found by using its co-ordinates on the great imaginary sphere projected onto the night sky, with the Earth at its centre – the celestial sphere. As we mentioned previously, finding a galaxy in this way is almost identical to the way you locate places on Earth using latitude and longitude; you just imagine the grid projected onto the starry realm. The only difference is that on the celestial sphere, latitude is known as declination (or Dec. for short) and longitude is known as…

Which is more important: the telescope or the eyepiece? The telescope gets lots of attention because it’s the most expensive and impressivelooking part of your setup – but without decent eyepieces, the views you get can be disappointing. What you ideally want is a good range of eyepieces, because different sizes of focal length are useful in producing better views of different kinds of objects. This is due to the fact that each eyepiece will have a differing field of view and magnification, depending on the telescope used. To find out what magnification you’re getting with any eyepiece takes a very easy calculation – you simply divide the focal length of the telescope, which is usually printed on a label on the scope near the eyepiece end, by the focal…

1. FOCAL LENGTH The focal length of a refracting telescope is the distance between its lens and the place where light rays from that lens are finally brought to a focus, known as the focal point. For a reflecting telescope, simply swap the word ‘lens’ for ‘mirror’. Focal length is one of the important numbers if you want to find out what magnification you are viewing the night sky with. The magnification is the focal length of your telescope divided by the focal length of your eyepiece. You get higher magnifications – good for viewing detail on the planets, for instance – with telescopes that have longer focal lengths. The downside to this is that longer focal lengths mean smaller fields of view, which are not always best for observing…

PROJECT 1 TWILIGHT SCENES This is a great way to start your astrophotography journey. Look for a composition that includes a twilight sky, a low crescent Moon, and maybe even a planet or two. You’ll get a better picture if you can frame the shot with some trees or buildings that will silhouette themselves against the sky. If you have a DSLR, set it to manual so you can vary the results. Fix it to your tripod and open the camera’s lens as wide as it will go (called a wide aperture). Focus at infinity and use different exposure times (vary how long the shutter stays open for). If you don’t have a DSLR and your camera is of the point-and-click variety, try it anyway – the results could be…

M13 TYPE Globular cluster WHEN TO LOOK Summer WHERE IS IT? Hercules Known as the Great Globular Cluster, this is the best of its kind in the northern hemisphere. From a dark site, M13 can just be seen with the unaided eye, but its bright, round form is a stunning sight through a pair of binoculars. It’s also great to look at through a telescope, which will resolve its individual stars. M45 TYPE Open cluster WHEN TO LOOK Winter WHERE IS IT? Taurus The Pleiades, or Seven Sisters, is one of the most splendid clusters in the night sky. With the naked eye, six stars of the cluster are easy to see, but counting up to 10 is possible. The cluster actually contains many hundreds of stars, and a decent…

The word Moon is responsible for our word ‘month’: one mooneth (or thereabouts) was the measurement of the time it took for the Moon to complete one orbit of the Earth in relation to the Sun. Although it’s given in schools as 28 days, the Moon’s changing appearance (it’s cycle of phases) takes just over 29.5 days. This is known as the Synodic Month. It represents the period from one full Moon to the next (or any other identical phase, for example half Moon to half Moon). The Sun is always shining on one half of the Moon – how much of the lighted side we see depends on where the Moon is in orbit around Earth. The new Moon happens when the Moon sits between us and the Sun,…

CRATER GRIMALDI SIZE: 173km across TYPE: Basin APPEARANCE: Visible even to the naked eye, this dark basin reveals fantastic detail through binoculars and telescopes, such as eroded walls, ridges and low hills. RIMAE SIRSALIS SIZE: 425km long TYPE: Rille system APPEARANCE: This series of fault lines is visible even in a small telescope, which will reveal Sirsalis’s main crack running straight for over 300km through a cratered environment. CRATER COPERNICUS SIZE: 94km across TYPE: Impact crater APPEARANCE: One of the Moon’s recognisable features and the result of quite a recent impact, a scope reveals terraced crater walls and central peaks rising from the floor below. VALLIS ALPES SIZE: 155km long AGE: Valley and rille APPEARANCE: A clean gouge through a mountainous region, the 18km-wide fault line can be easily visible…

One of the most breathtaking astronomical events you can witness is a total eclipse of the Sun, also known as a total solar eclipse. Not only is it an experience you’ll never forget, but it also shows the Solar System in motion through the fortunate alignment of three astronomical bodies. The first object is our planet, the Earth, which slowly orbits the second object, the Sun. The third object in the equation is the Moon. We get an eclipse when the Sun, Moon and Earth are temporarily aligned. The next total eclipse takes place this year on 13 November, but totality will only be seen from Cairns, Australia. It will, however, be seen as a partial eclipse in central Chile, and areas of New Zealand, such as Auckland and Christchurch.…

Thinking back to ‘ye olde dayes’, there were no space probes visiting the planets. Telescopes were able to reveal that Venus was covered in cloud, but it was a guess as to what was underneath: both jungle and seas were respectable ideas. I wonder what these pioneering astronomers would think of our current knowledge, together with all the stunning images that go with it. Today, in our informationrich world, most people know the basics about the planets. It’s easy to forget the angst the early astronomers suffered due to their serious lack of reliable, scientific information. In part one, I gave a general overview of our entire planetary system, giving you the bigger view of how the planets move together, helped along by that fine force of gravity. Now that…

Looking at Saturn through a telescope is a glorious sight. However, Saturn is best viewed when the ringed planet is at opposition – when its orbit brings it to its closest point to Earth. The next time you can get a ‘close-up’ view of Saturn like this will be when it’s next at opposition on 28 April 2013, then again on 11 May 2014 On these dates Saturn will be at its biggest and brightest in the sky – although the ‘biggest’ part is only apparent through a telescope. This applies to Saturn’s moons too, which will also be at their optimum brightness for observing. The planet and its moons’ visibility during this period, along with the fact that the angle at which its rings can be seen varies, gives…

There you are on holiday, sitting in a bar overlooking the sea on some Mediterranean island after dark. One of your friends puts down their drink and mentions that the stars look so much brighter than at home. You all gaze skyward just as a particle the size of a grain of sand smashes into Earth’s atmosphere, leaving a bright trail across the night sky as it vaporises. There are gasps and wishes are made in honour of witnessing a shooting star. Actually, a ‘shooting star’ is just the popular name for this sort of event. Astronomically you’d call it a meteor and each one that occurs has a great tale to tell. Most meteor-making objects come from comets, which are icy, dusty and dirty chunks that orbit around the…

Above the northern horizon a green arc melts into view. As you watch, red and green rays begin to emanate from it. These grow into long weaving ripples that stretch like ribbons across the entire sky, almost as if they were blowing in the wind. You are witnessing one of the true marvels of the natural world: an aurora. The phenomenon is caused by charged particles streaming out of the Sun and interacting with Earth’s magnetic field – our planet’s protective shield – which channels them down towards the ‘magnetic’ poles. As the particles reach lower altitudes, usually between 80 and 200km, they hit and excite the the gases in Earth’s atmosphere, causing a distinctive and colourful glow. The magnetic poles are about 11° away from the geographical poles (the…