Guide to the Night Sky. Brecon Beacons National Park & Dark Sky Wales

Transcription

1 Guide to the Night Sky Brecon Beacons National Park & Dark Sky Wales 2010

2 W elcome to the first edition of Dark Sky Wales (DSW) guide to the night sky. This guide has been produced in conjunction with the Brecon Beacons National Park and is designed to provide you with all the information needed to enjoy the wonderful dark skies the National Park has to offer and more importantly to help you promote your business to a potential new customer base. Dark skies are becoming ever more difficult to find in the UK with countless people in built up areas not even able to see many of the most recognisable constellations. This significantly hinders one particular group, amateur astronomers (250,000 currently in the UK), whose enjoyment of their hobby has resulted in the vast majority of them now visiting dark sky sites both here in the UK and abroad. Many amateur astronomers will spend thousands of pounds on equipment and similar amounts on travel over the years to discover that perfect location. Furthermore, astronomy is not seasonal however; many astronomers actually prefer the dark night skies of winter ideal for those businesses that are quiet during this period. This is where the National Park can play a major role. The Brecon Beacons National Park situated in South Wales covers an area of 520 square miles, many of which provide skies barely touched by light pollution. Better still these areas are easily accessible with good transport links to the whole of the UK providing a unique opportunity for individuals to enjoy the wonders the night sky has to offer. From simple star gazing for the casual observer to a myriad of deep sky objects just waiting for the more accomplished astronomer to explore and even image. So why not encourage tourist to visit the wondrous dark skies of the National Park then stay and experience this magical area and renowned Welsh hospitality during the day! What are Dark Skies? Dark Skies are exactly what you d expect, dark! They allow views of the night sky that are seldom seen these days from built-up areas where less than 10% of people are able to see the Milky Way. Unfortunately, more and more of the UK and in fact the world are losing this valuable commodity. Street lights, security lighting etc are now the order of the day and have for many decades encroached into the realm of the dark sky, stealthily removing humanities right to enjoy starry nights. Fortunately, a band of intrepid individuals have fought back by establishing several organisations such as the International Dark Sky Association, Campaign for Dark Skies, Dark Sky Awareness and Dark Sky Discovery (UK project) who have begun to influence government policy and public perceptions. At the forefront of this campaign is the development of dedicated dark sky parks where the night sky is preserved for future generations. Fortunately, due to the remoteness of certain locations within the Brecon Beacons National Park they offer a window of opportunity for the development of a dark sky park and ensure the retention of those pristine dark skies. Moreover, they also present businesses within the National Park the prospect of Astro-tourism which is currently a growth market. Keeping the Dark Skies Dark There are three main types of light pollution: sky glow, that lights up the night sky and spoils our view of the stars; glare, that can dazzle us when present in a dark place; and light trespass, the spilling of light beyond the area being lit. Each of these kinds of light pollution is a form of obtrusive light that can annoy stargazers and anyone wishing to experience darkness, waste

3 money, waste electricity, and result in the unnecessary production of greenhouse gases. The most important thing to remember is think before you light - Is the light necessary? If so, is it the right brightness? Might it be a nuisance to others? What can you do to minimize these things? In general, don t over light, turn lights off when you don t need them, consider turning your outside lights off at a certain time of night (say after 10pm), and make sure your lights are shielded and pointing in the right direction! Benefits to Business The Brecon Beacons National Park has just begun the long process of establishing itself as a designated dark sky area and with your help should achieve this goal in the coming years. By realising this status it is hoped that many more tourists will be attracted to the area and aid the local economy in these difficult economic times. If successful it will become only the UKs second park to obtain the status after Galloway Forest Park in Scotland 1. It will take a few years and a lot of hard work to obtain but with the help of DSW, The University of Glamorgan, the National Park Authority and most important of all local business we are confident that this can be achieved. Ultimately, to make this a successful venture investment in infrastructure and resources must play a big part. This is where business plays a major role! It is expected that business would take the lead in this area by educating/informing us of their requirements. Moving forward as a group funding would then be sought to initiate the required infrastructure changes/requirements. Through this approach it is hoped that an influx of new tourists will see this project flourish and most important of all provide a sustainable future. Astro-Tourism has for many years been the exclusive realm of foreign lands as very few UK tourist operators offered such experiences. Therefore, this market is a relatively untapped income stream with a conservative estimate of 250,000 amateur astronomers actively participating in astronomy throughout the UK. The appeal of dark skies and proximity of location will offer a new and comparatively cheaper alternative to foreign travel. Additionally, with the assistance of the Brecon Beacons National Park Authority and DSW business will be able to offer themed weekends/days throughout the year including potential star parties. Business will be expected to undertake some remedial work to their property if required. This remedial work will involve the provision of adequate lighting that corresponds to the requirements of the IDA guidelines. Such work would involve minimal financial outlay. Ultimately, this opportunity allows business to increase their income potential by utilising the local environment. In doing so the following benefits are achievable; Benefit to Business; New market Low or no initial outlay on infrastructure Off peak business Specific events supported by BRECON BEACONS NATIONAL PARK AUTHORITY and DSW Increased revenue Benefits to Astronomer; Proximity of location Cheaper alternative to international travel Use of own equipment 1

4 Locations At present DSW, The University of Glamorgan and Brecon Beacons National Park Authority are undertaking dark sky studies of certain locations within the national park in order to ascertain the most likely areas to achieve dark sky status. However, it would be beneficial for those businesses that feel that their location fulfils the criteria 2 set out by International Dark Sky Association to contact either DSW or the National Park Authority in order for any necessary data to be gathered. In the meantime, the Brecon Beacons National Park Visitor Centre, also known as the Mountain Centre provides easy access, ample parking and dark skies for those business and tourist who wish to take advantage of dark skies. Up to date information will be provided at the centre for those wishing to observe objects of particular interest for that month/season along with simple instructions on how to observe successfully. Additionally, regular training courses and observing sessions will be held in order to assist businesses to integrate astro-tourism into their business plan. What you need to enjoy the sky Many people often gaze up at the night sky and wonder what that is? People all over the world are captivated by the sights they see when looking up at the night sky, but more often than not the majority of those people do not know what they are looking at. This section will show you how to enjoy the night sky without a telescope. When people first become interested in astronomy they generally look on the internet or pick up a magazine to see what s required. Confused by the amount of equipment on sale and not sure of what to purchase their interest soon fades. In fact, there are many wonderful things you can discover just by lying down on the grass and looking up. For instance, when you look up at the sky at night you can see at least five of the planets in our solar system with your naked eye along with the Milky Way, comets and meteors and even galaxies. To Maximise Potential First you want to ensure that when you are trying to identify constellations or just find the five planets that are visible that you do so on a clear night. This means that there are no clouds, low lying fog, or that there is no moon to hamper your view (not so important for planets). Get comfortable. When it comes to astronomy you must bear in mind that you will be outside at night for a good amount of time. This means that you should always dress for the occasion and bring something comfortable to rest your body on. This could mean that you bring extra layers to fight off the chill as well as a few lawn chairs or even blankets to lie on. Find the darkest spot you can manage. This is extremely important as any light source whether it is from the moon or street lights in your town will hamper your view of the night sky. The best place to look for is somewhere out of town with a large enough clearing so that the trees are not in your way either. Prepare for the enormity of it. Most people simply do not realize just how much there is to see out there at night and because it takes up to a half hour for your eyes to fully adjust it is important to know that the first few times will be difficult to take in. 2 The International Dark Sky Associations criteria are provided in Appendix A.

5 What you ll need When you are out under the stars trying to identify planets and such you are not going to want to keep running back to your home for supplies so make sure you bring everything you would need. So be prepared making sure that all sorts of important things are to hand. The essentials are; Lunar chart Planisphere Warm clothes (extremely important all year round, not just in the winter) Comfortable sitting arrangements Flashlight with red cover over light Snacks (warm drinks etc ) All of these things can be purchased relatively cheaply or are indeed free 3. When to go out Short Answer Whenever it s clear! While the dark skies are amazing on a clear night, clouds can often spoil the view. To fully appreciate the wonder of the dark skies in the Brecon Beacons National Park you need to go out when there are as few clouds as possible in the sky, preferably when there are none. You might therefore need to be flexible with when you observe, taking any opportunity as it arises. If it s dark over dinner time, skip dinner. If the forecast is for clear skies before dawn, get up early. Long Answer Assuming the skies are clear, there are several other factors on when you should observe. Twilight Whereas the Sun might set in winter around 4pm, you ll still need to wait until 6pm to get properly dark skies, as the sun sinks low enough below the horizon not to spill light up into the sky at dusk. As a rule, avoid a couple of hours after sunset and before sunrise, if you want a truly dark sky. Having said that, the park is spectacular at dawn and dusk too! Seasons Winter is the best season for stargazing, with long dark nights, but you can catch dark skies for most of the year. It s only really in the summer months when the sky never gets properly dark. Between early May and early August the sky will always have some light in it, even at midnight. This is especially a problem between June and mid-july when the sky remains blue-tinged throughout the night. It is still possible to observe during the summer months, but far fewer objects will be on display. 3 Planisphere, Red-light torch and lunar chart can be found in this pack.

6 The Moon As a rule, you should try and avoid observing when the Moon s in the sky (unless, of course, you re observing the Moon! see page 17), especially when it s a full Moon. The best two weeks of any month for observing fall on either side of the New Moon. But don t let all this put you off: if it s a clear night head outside you won t be disappointed! What you will see: learning your way around the sky One of the biggest challenges for new stargazers is identifying just what they are looking at in the night sky. This is made even more difficult in a truly dark sky, such as you ll see over the Brecon Beacons National Park, as there are so many stars on view. On a clear moonless night you will see thousands of stars overhead. These are grouped into 88 constellations, but to begin with you will only want to learn a few of these in order to get your bearings. Here is a brief description of which constellations to look for, and on the next page are simple star charts. Looking North The Plough is perhaps the most easily recognised group of stars in the northern sky and it is a very useful skymark. The Plough is always above the horizon and allows us to find Polaris, or the Pole Star. If you imagine the plough as a saucepan, then you can follow the two stars furthest from the handle, up towards another not-particularly-bright star. This star is Polaris. If you are looking at this star, you are facing north. On the other side of Polaris is a W of stars (or an M depending on which way up it happens to be; the stars appear to rotate anti-clockwise round Polaris once every 24 hours). This is the constellation of Cassiopeia. These stars in the northern sky are the same all year round, so you will always be able to find them on a clear night. Looking South The stars in the southern sky change as the season s change, the winter skies being perhaps the most exciting, and as its dark for longer, they re easier to see too. One of the most easily recognised constellations in the sky is Orion the Hunter, with his Belt. You can use Orion s Belt to find other shapes by following the line of the belt right, till you come to a V-shape of stars Taurus head and then a small group of faint stars the

7 Seven Sisters, or Pleiades cluster. From the Brecon Beacons National Park you should look for the Orion Nebula, a faint smudge on his sword, where new stars are being formed before your eyes. This nebula isn t visible from a city, and makes an excellent binocular object. Follow the line of the belt left, and you come to Sirius, the Dog Star, and brightest star in our night sky. What Next? There are, of course, far more stars to be seen than just these, but if you can find these objects reliably, then you can use them to find your way round other constellations too. Astronomical magazines publish monthly sky charts with much more detail than the following star-charts, including the current position of the planets, but you ll find it helpful to master these first before progressing onto more complicate charts. What you will see: pocket star charts Dark Sky Scotland produce simple pocket star charts to help visitors locate certain constellations which only show in the locale, examples are attached. DSW is in the process of developing star charts for the Brecon Beacons National Park.

8 Things to look for: stars and constellations Over the previous three pages we have described a few of the more recognisable stars and constellations visible from Brecon Beacons National Park. Of course there are many more to see. The following is a list of the constellations visible at different times of the year. Charts for these are not given, so find a detailed star chart for the date you re observing, and try to find them on that. Winter Stars Spring Stars Summer Stars Autumn Stars Orion The Hunter Taurus The Bull Gemini The Twins Virgo Bootes Hercules Cygnus the Swan Lyra the Harp Aquilla the Eagle Pegasus Andromeda Perseus Things to look for: the Moon The Moon causes natural light pollution, which drowns out the light from faint stars and the Milky Way, and so it is best to avoid stargazing when the Moon is in the sky. However, the Moon itself can be a very rewarding observing target in its own right. It is best observed when a crescent or half Moon, setting after the Sun in the evening. Through even modest binoculars you can make out a lot of detail on the Moon s surface, especially around the terminator, the line between the lit and unlit part of the Moon s surface. This line, when viewed through binoculars can be seen to dip into craters and rise over mountains, giving a real sense of the 3D surface of the Moon. On this image of the Moon, and when you see the Moon in the sky, even with the naked eye, you can make out shapes on the surface. These are flat, smooth regions on the Moon s surface called mare, or seas. They were so named before anyone knew that there was no liquid water on the Moon. The mare often gives the impression that there s a man in the Moon, but in reality it looks a bit more like an upside-down rabbit. Can you see the body, head and ears of the rabbit in the picture above? Have a look next time you see the Moon in the sky. You need good eyesight to spot it, but it s there! The rabbit s head is the Sea of Tranquillity, where Neil Armstrong and Buzz Aldrin set foot for the first time ever in 1969.

9 Things to look for: planets There are eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune (Pluto is no longer considered to be a planet; it has been demoted to the status of dwarf planet ). Of the eight planets, five are visible to the naked eye in the sky over the course of the year, although not all at the same time. The word planet comes from the Greek planeti, meaning wanderer. This is because the planets, as they orbit the Sun, appear to move against the background of fixed stars and constellations, changing position as the year goes on. The closer a planet is to the Sun the faster it moves against the background stars, so the more its position changes from night to night. As their positions vary, you need up-to-date information about where planets are visible ( ) but here is a quick summary of what you can expect to see in each case. Mercury By far the hardest naked-eye planet to spot, Mercury is never far from the Sun in the sky, so make sure you wait till the Sun has set before trying to find it. It is very dangerous to observe when the Sun is in the sky, even with your naked eyes, but especially so with binoculars or a telescope. Mercury will appear to be a tiny faint dot against the dusk or dawn sky. Venus Like Mercury, Venus is only ever seen just after sunset or just before sunrise. It is therefore known as the Evening Star or the Morning Star. It is the brightest thing in the sky after the Sun and the Moon, and can show phases like the Moon when seen through a telescope or binoculars. Mars The red planet looks like a brilliant red star. The red colour was associated with blood and war, hence its name after the Roman god of war. In reality Mars red colour is as a result of the rust on the rocks on the surface of the planet. Jupiter The largest of all the planets in the solar system, Jupiter can get very bright indeed. Seen through a steady pair of binoculars you might spot the four Galilean satellites, moons of Jupiter named in honour of Galileo who discovered them 400 years ago. Saturn The second largest planet is not quite a bright as Venus, Mars or Jupiter in the sky, but a small telescope will reveal its beautiful rings, looking like bulges on either side of the planet s disk. Things to look for: the Milky Way Our galaxy, the Milky Way, contains 100 thousand million stars. Most of these are too faint for our eyes to detect, and so we can only see the brightest few thousand stars around us as individual points of light in the night sky. However the light from the remaining billions of stars blends together in the night sky forming a trail of grey light across the sky, which we call the Milky Way. The Milky Way will look stunning on a clear moonless night. Even without binoculars you should be able to see structure

10 within the Milky Way, patches where it s a bit darker, or a bit brighter. The Milky Way is always visible in the sky, however depending on time of night and time of year it might be low on the horizon and therefore slightly more difficult to see. However it is worth persevering. The Milky Way is impossible to see from cities, and so very few people in the UK have ever seen it. Things to look for: Other Galaxies and Nebulae Studded amongst the stars in the night sky you will spot, if you observe for long enough, several small fuzzy patches. Ancient astronomers, not knowing what they were, called them nebulae, or clouds. Now we know that these nebulae are in fact many different kinds of objects, from entire galaxies, to spherical globular clusters of stars, to clouds of gas and dust in space where new stars are being born, to the cold remnants of long dead stars. These objects are amongst the most difficult to spot in the night sky, and are certainly never visible from light-polluted cities. Some of the most impressive nebulae are: The Pleiades (M45) or the Seven Sisters Find The Pleiades using Orion s Belt; trace a line up and to the right from Orion s Belt, past the V-shape of the horns of Taurus the Bull, to the small group of stars that is The Pleiades. This cluster is actually made up of thousands of young stars, but our eyes are only good enough to see seven or eight of them. In fact you can test your eyesight using the Pleiades: how many can you count? The Orion Nebula (M42) Find the Orion Nebula just below the three stars of Orion s Belt. The faint line hanging from his belt is a sword, and within the sword is a fuzzy patch that is the Orion Nebula, a stellar nursery where new stars are being born. The Orion nebula appears as a fuzzy blob to the naked eye, but more details can be seen through binoculars.

11 The Andromeda Galaxy (M31) Find the Andromeda Galaxy from the W-shape of Cassiopeia. The right hand V of the W-shape points to the very faint elongated hazy patch of this galaxy. Look at the Andromeda Galaxy and you are seeing the light from 100 thousand million stars, in a galaxy so far away that it took the light from those stars over two million years to reach the Earth. The Seven Sisters, The Andromeda Galaxy and The Orion Nebula all have M-numbers after them as they are objects in the Messier catalogue, a catalogue constructed by Charles Messier. If you see an object marked on a star chart with an M-number, it might be worth a look. Things to look for: Shooting Stars The name shooting star is very misleading. These objects that can be seen streaking across the night sky are not stars at all, but in fact tiny bits of space debris being hoovered up by the Earth as it sweeps around the Sun. As these particles of rock pass through the Earth s atmosphere they are heated up and start to glow white-hot, and so for a split-second can appear as streaks of light in our night sky. On any clear night you can see lots of shooting stars (or to give them their proper name meteors) if you sit outside for long enough, but there are some nights of the year where your chances of seeing them increase dramatically. This is because, every so often, the Earth passes through a particularly dense region of rocky particles. At such times we get what astronomers call a meteor shower. During such showers you might see as many as a hundred shooting stars per hour! The dates of some particularly good meteor showers are roughly: 03 or 04 January Quadrantids Meteor Shower up to 120 per hour 12 or 13 August Perseids Meteor Shower up to 100 per hour 13 or 14 December Geminids Meteor Shower up to 120 per hour These rates are the maximum you d expect to see in perfect conditions with the shower happening directly overhead. Conditions never are perfect, although in the Brecon Beacons National Park, given clear skies and no Moon, they are as close to perfect as it s possible to be in the UK.

12 Observing meteor showers requires patience, as you ll probably be outside for many hours. One of the best bits of equipment for meteor watching is a reclining deck chair! To find out the exact dates of these and other meteor showers, visit the Society for Popular Astronomy s Meteor Section website at: Things to look for: Satellites Everything we ve described so far are natural objects, but it is possible to observe man-made objects in space too: satellites in orbit round the Earth. Satellites are only visible to us if sunlight reflects off their surface at just the right angle. For that reason, satellites can appear to flare up as they orbit the Earth and the angles align for a just a few minutes to make them visible to us. Like shooting stars, you can see satellites on any night of the year if you spend long enough observing under a dark, moonless sky. Most of them will tend to be very faint however, and so you might prefer to look for satellites that can be predicted to get very bright when viewed from the Brecon Beacons National Park. The best (brightest) satellites to look for are called Iridium Flares, so named because they can flare up to many times brighter than even the brightest planet Venus. The flares last for only a few seconds (up to around 20 seconds) as the satellite gets to just the right angle between us and the Sun. You might also be fortunate enough to see the International Space Station (ISS) (the largest man-made object ever put into space) pass overhead, along with the astronauts that are on board carrying out scientific experiments. You can find out exactly when and where Iridium Flares and the ISS are expected to appear above the Brecon Beacons National Park by visiting: You enter your location via Configuration > Select from map. Once you ve done that you can go to Satellites > Iridium Flares > Next 7 Days or you can go to Satellites > 10 Day Predictions for ISS. This will tell you the brightness (magnitude) of the satellite pass. The lower the number the brighter it will be. Negative magnitudes are BRIGHT. It will also tell you the time to look (and this is exact time, so make sure your watch is accurate), the direction to look (under azimuth it will quote an angle and a useful compass direction such as SE, NW, E etc), and what height above the horizon to look (under Alt). This height is quoted in degrees. As a rough rule your clenched fist at arm s length covers ten degrees, so if you want to look 40 degrees above the SE horizon use a compass (or the Pole Star!) to find SE and then count up four fist-heights above the horizon. At the exact predicted time, the satellite will appear. List of Useful Websites General Astronomy Portal to the Universe a one-stop-shop for astronomy news Universe Today another great astronomy news website The Night Sky this month - List of Meteor Shower Dates Time and Direction of Satellites Northern Lights Alerts

13 Astronomy Now Magazine Dark Skies and Light Pollution Campaign for Dark Skies International Dark-sky Association Dark Sky Scotland This brochure has been produced in collaboration with the Brecon Beacons National Park Authority and the assistance of Collbor8 and European Regional Development Funding through INTERREG IVB