Broadly speaking, there are two types of meteor. Sporadic meteors can appear at any time and anywhere in the sky. However, the appearance of shower meteors is much more predictable. These are associated with comets, and the particles that give rise to the meteors we see originate in material which has been thrown off by the parent comet as it passes through the inner solar system. This material initially goes to form the coma and tail of the comet. However, because the gravitational pull of the comet is very weak, the particles break away and eventually become spread out all along the orbital path of the comet.

The Earth’s orbit around the Sun carries it across the orbital paths of numerous comets at different times of the year. When this happens, and because the cometary orbit is littered with particles, a larger than average number are drawn into our planet’s atmosphere, which in turn results in relatively high numbers of meteors. Many meteor showers are fairly weak and produce only a small rise in meteor activity. However, the Perseid shower, produced during July and August when the Earth crosses the orbital path of Comet Swift-Tuttle, is the most famous and by far the most active of all.

Because the particles associated with comets travel around the Sun in parallel paths, the meteors they produce will all appear to emerge from the same point in the sky, an effect similar to that seen with railway lines which are also parallel but which seem to merge in the distance. This point is known as the radiant and the meteor shower is usually named after the area of sky in which the radiant lies. For example, the Perseid radiant lies in the constellation Perseus as shown on the chart below.

WATCHING THE PERSEIDS
Meteor watching is fairly straightforward and involves nothing more than laying under a starry sky making sure that (in spite of it being summer) you’re wrapped up warmly. The night of maximum activity for the Perseids is 12th August at which time the Earth is passing through the densest part of the cometary particle swarm. On that night anything up to 50 or more naked-eye shooting stars may be seen per hour. This year, the Moon will have set by early evening and so, assuming the sky is cloud-free, conditions for watching the Perseids are quite favourable.

If you spot a Perseid meteor it will first appear some distance from the actual radiant. Any meteor you do see can be confirmed as a Perseid by tracing its path back. Perseids will be seen to radiate from a point in the sky to the top (north) end of the constellation Perseus which, during evenings in early August, will be visible in the north eastern sky, a little way below the prominent W-shaped Cassiopeia and above the bright star Capella. The Perseid radiant is shown on the chart and it is from this point that the Perseids will seem to emanate. Those meteors whose paths don’t trace back to this point are sporadic meteors and not from the Perseid shower.

So, if you happen to be out walking on the night of 12th August – or indeed between now and then – keep an eye out for the Perseids… happy meteor-hunting!

Things get started with a chance for you  to improve your confidence in exploring the countryside by gaining basic map reading and compass skills and discovering what can be done where. The event on Thursday 22 July includes practical sessions, so participants should wear walking clothing/boots. Booking is essential by contacting the National Park Centre in Dunster 01643 821835. Meet at Dunster 10am, no dogs please.

On Monday July 26 the whole family can join a National Park ranger to find out ‘who is eating who’ in the rockpools of Lynmouth and ‘what is hiding where?’ Meet on seafront opposite cliff railway, Lymouth SS722497 at 2pm for approx 2 hrs.

Finally, the Simonsbath Evening Deer Search on Tuesday 27 July offers the unique opportunity to try and locate the red deer of Exmoor. Meet at Ashcombe Car Park, Simonsbath SS774395-7 at 7pm for 2 hours /3 miles. Binoculars, walking boots/clothing are essential. No dogs please.

Please note there is a small charge for these events, for more information on any of them please call the contact number provided or the Dulverton National Park Centre on ✆ 01398 323841. You can also visit www.exmoor-nationalpark.gov.uk for an interactive walking map ranging from easy to strenuous.

Night wildlife walk, Ashridge Estate, Hertfordshire
Join in an evening of night-time discovery on the Ashridge Estate. Enjoy a talk by a local wildlife expert Brian Barton, followed by a guided walk with the National Trust’s wardens. Listen for ‘glis glis’ in the woods, use ultrasonic bat detectors to identify where bats are feeding, and learn about other mysterious nocturnal creatures – then enjoy a
moth-trapping session with Bucks Moth Group in the woods.
Date: 09 July
Time: 9pm – 12pm
Admission charges are £8 adult and £4 child.
Booking is essential, please call ✆ 01442 851227

* * *

Charlecote Park Bat Walk, Warwickshire
Enjoy a walk in the grounds at night looking for these fascinating
creatures. The walks will be lead by volunteers from Warwickshire
Bat Group who will answer all you questions on these night-time creatures.
Dates: 03 and 14 July
Time: 8.30pm – 10.30pm
Admission charges are £5 per person.
Booking is essential, please call ✆ 01789 470 277

* * *

Bat hunt walk, Kingston Lacy, Dorset
Spot and hear bats at White Mill with a countryside warden.
Date: 12 July
Time: 9pm – 10.30pm
Admission charges are £5 adult and £2 child.
Booking is essential, please call ✆ 01202 883402

* * *

Bat and moth night at Sheringham Park, Norfolk
Date: 02 July
Time: 8.30pm – 10.45pm
Take an evening stroll with our warden to learn about the species
of bats and moths in the park when they are most active.
Suitable for adults and older children.
Admission charges are £5.50 adult.
Booking is essential, please call ✆ 01263 820550

For more information on National Trust events, visit www.nationaltrust.org.uk/events and stay tuned for more walk picks for August!

Image © National Trust

Canes Venatici: Hunting dogs of the northern sky

The conspicuous pattern of stars forming the Plough (actually part of the much larger constellation Ursa Major, the Great Bear) is visible high in the sky during spring evenings and the group is quite unmistakable. As we have seen in previous blogs, the Plough is a useful pointer to many other star patterns, including the much-smaller constellation known as Canes Venatici.

Known to the astronomers of ancient China by the somewhat-unromantic name of Chang Chen – ‘a seat’ – and to later Arabic astronomers as Al Karb al Ibl – or ‘the Camel’s Burden’ – the tiny constellation of Canes Venatici, the Hunting Dogs, is visible as a small triangle of stars a short way below the ‘handle’ of the Plough as shown below.

The brightest star in Canes Venatici is Cor Caroli, a name which means Charles’ Heart, and which was given to the star by Edmund Halley in memory of Charles I. However, the star has the alternative name Chara and, along with Asterion, these two stars are shown on ancient charts as representing two dogs held on a leash by Bootes, the Herdsman. Bootes is depicted by a larger constellation a little way to the east (and which will be described in next month’s blog). Arcturus, shown on the chart below, is the leading star in Bootes who, with the help of Chara and Asterion, is eternally pursuing the Great Bear around the northern sky.

If you have a small telescope you might like to take a closer look at Cor Caroli which is in fact a double star. Each of these stars is white and similar in size and brightness to our own Sun. The pair shine from a distance of around 110 light years, which means that the light we see from Cor Caroli actually set off on its journey towards us around the end of the reign of Queen Victoria!

Although only tiny, the constellation Canes Venatici is notable in that it plays host to the celestial showpiece Messier 3, or M3, located on a line from Asterion through Cor Caroli and extended towards the bright star Arcturus as shown here. M3 is a member of a class of objects known to astronomers as globular clusters and, like all globular clusters, this object lies outside our Galaxy. M3 is located at a distance of well over 30,000 light years and contains around half-a-million stars compressed, as its descriptive name suggests, into a globe-shape with an actual diameter of around 200 light years.

If you have really keen eyesight, and the sky is very dark, clear and moonless, you might be able to pick out M3 with no optical aid whatsoever. However, you’re best looking for it with a pair of binoculars. When seeking out this object, and others of its type, try to look for a patch of luminosity rather than a point of light. Once you’ve found it, M3 should be visible as a tiny, spherical cloud.

It is a sobering thought that, should you manage to glimpse M3, the light you are seeing from this remote object set off on its journey towards us over six times as long ago as the age during which Stonehenge and the Great Pyramid of Giza were constructed – the universe is truly a huge place!

Now the evenings are warmer, why not try spotting the celestial hunting dogs and seeking out its remote but inspiring globular showpiece? Happy stargazing!

Along with the Plough (actually part of the larger constellation Ursa Major, the Great Bear) and Ursa Minor (the Little Bear), the prominent ‘W’ formation of stars known as Cassiopeia completes the trio of conspicuous star groups that grace the northern skies. Cassiopeia stands out quite well and can be spotted fairly easily, located low in the north-western sky during spring evenings. However, it can also be found by using the two end stars in the ‘bowl’ of the Plough (located high in the sky a little to the east of the overhead point) as your guide. If you follow the imaginary line from Merak, through Dubhe and past Polaris as shown below, you will eventually arrive at Cassiopeia.

The constellation represents the mythological Queen Cassiopeia, wife of King Cepheus and mother to Andromeda, the beautiful maiden rescued by Perseus from the terrible sea monster. Cassiopeia is what we call a circumpolar constellation, which means that it never sets as seen from the latitudes of Great Britain, from where it is located almost overhead in autumn. The group moves around the heavens, tracing a circle around the Pole Star, eventually skimming the northern horizon, where she can be seen over the rooftops during spring evenings.

The constellation lies within the Milky Way and the whole area is seen to abound with stars. On a really clear night you should spot around fifty stars within the group, although binoculars will reveal many fainter stars scattered across this area of sky. Although most of these stars are below naked-eye visibility, their combined light produces the effect we call the Milky Way. During spring evenings the Milky Way can be seen as a faint shining band of light spanning the sky from the north, crossing Cassiopeia and down to the south. Not usually very clear to city-dwellers, it can be a superb sight when viewed under a really dark and moonless sky.

Cassiopeia contains six prominent stars, the brightest of which is Schedir, from the Arabic Al Sadr – ‘the Breast’. Schedir is a giant star, lying so far away that its light takes over 160 years to reach us. By comparison, Caph is a dwarf, although it appears almost as bright as Schedir because it lies at a distance of only 47 light years. Another giant is Cih, a star so distant that its light set off towards us during the reign of Edward the Second. Ksora, named from the Arabic for Knee, is a white star, like most of the main stars in Cassiopeia. The exception is Schedir which has an orange tint that is detectable with the naked eye but which can be spotted more easily through binoculars.

It must be pointed out that, unless you are a fairly experienced observer, individual colours of stars do not readily stand out. The reason for this is that most of the stars we see in the night sky are not bright enough for their colours to register on our eyes, although even a modest pair of binoculars can be a great help when seeking out different star colours.

Whether you want to scan the rich backdrop of the star fields of the Milky Way or simply pick out the heavenly ‘W’, Cassiopeia is the constellation to look for. Go out there and join her under the starlit spring sky. Happy stargazing!

Along with its larger relative, the Little Bear (or Ursa Minor) is one of the oldest depicted star patterns and appears in a catalogue of constellations compiled during the second century BC by the Greek astronomer Ptolemy. Visible high in the northern sky as seen from mid-northern latitudes, the Little Bear is easily found by using the two end stars in the ‘bowl’ of the Plough as pointers, as shown below. Just follow a line from Merak through Dubhe you will reach the star Polaris – the brightest star in Ursa Minor and the end of the Little Bear’s tail.

Although Ursa Minor isn’t the most prominent of constellations, it can be picked out fairly easily because the area around it is devoid of bright stars. It roughly resembles the Plough in shape and stretches away from Polaris, the main star in the group. Polaris, or the Pole Star, as its name suggests, marks the position of the north celestial pole. This is the imaginary point in the heavens which lies in line with the Earth’s axis, and consequently directly overhead as seen from the North Pole and in the direction of north when viewed from elsewhere on the Earth’s surface. Polaris appears to remain stationary as the Earth turns on its axis, with all the other stars appearing to go round it every 24 hours.

If you look at the celestial bears you will notice that they both have long tails – unlike their earthly counterparts. Of course, there is a legend to explain this. Ursa Major (the Great Bear) represents the legendary maiden Callisto – who was so beautiful that the Roman goddess Juno (wife of Jupiter, the King of the Gods) became jealous, and turned her into a bear. Years later, Callisto’s son Arcas almost killed the bear while out hunting. Jupiter then turned Arcas into a bear and, in order to save them both from Juno’s clutches, grabbed both animals by their tails and swung them high up into the sky where they can be seen to this day. Naturally, the tails of both animals became stretched in the process!

At the other end of the constellation, the stars Kochab and Pherkad are known collectively as the Guardians of the Pole. Pherkad is actually a wide double star and both stars that form this double can be seen with binoculars. The pair are white and orange-yellow, although you may need a telescope to bring the colours out properly. Kochab is also orange-yellow in colour and is one of the closest stars in Ursa Minor, its light taking just over a century to reach us.

Polaris, on the other hand, shines from a distance of 680 light years. In other words, the light we are seeing from Polaris set off towards us around the reign of Edward III. The star appears relatively faint although in reality it is around 6,000 times as luminous as our Sun and only appears faint due to the fact that it lies at such a great distance from us. So though the winter evenings are fairly chilly, keep an eye to the heavens when you’re out walking and think of the Little Bear and the Pole Star as your celestial guides. Happy stargazing!

Exmoor National Park, which  is applying to become the first English National Park to achieve ‘Dark Sky Park’ status, will be hosting a Geminids-watching event this coming Sunday 13 December at The Sportsman’s Inn, Sandyway (EX36 3LU) from 8.30pm.

According to the park, “the Geminid shower is often referred to as the most reliable meteor shower of the year and this year, the peak of the shower is predicted to occur on the night of the 13 December which should provide an ideal opportunity to learn about this incredible phenomenon. The Geminid shower often coincides with a full moon, but not this year so, weather permitting, there will be a chance to see meteors, often known as shooting stars, streak across the sky. Also on hand will be samples of real meteors for people to examine.”

A spokesman for the park explains “We are keeping our fingers crossed for a nice clear night which means that it will be cold so people are advised to wrap up very warmly and there will of course be the pub to go into for a warm-up or some food between star gazing. If it’s cloudy, there will still be plenty to see during a presentation by a local astronomer within the comfort of the pub.”

Families are welcome and anyone wishing to attend should call The Sportsman’s Inn on 01643 831109 to book a place.

To round off the International Year of Astronomy, the North York Moors National Park Authority is once again teaming up with The York Astronomical Society to host a free star gazing event on Saturday 12 December at Sutton Bank National Park Centre.

Dark skies at night and clear unpolluted air are special qualities of the UK’s 15 national parks making them ideal locations for star gazing. The Star Party will start at 6pm and will include two illustrated talks from the society’s astronomers. The café at Sutton Bank National Park Centre will be open from 5pm serving a selection of food and drink. Telescopes will be provided but people are also encouraged to bring their own telescopes along for tips on getting the most from them. Members of The York Astronomical Society will be on hand to offer help and information throughout the evening.

“With a telescope and the right weather conditions, the night sky can be a magical thing to observe,” says Martin Whillock, Secretary of The York Astronomical Society. ”The conditions around Sutton Bank, with its low light pollution, are ideal for getting some excellent views. Come well wrapped up and join us for what promises to be a very exciting evening.”

For further information on the star gazing event, contact Martin Whillock on tel: 01347 821 849 or email: martin@whillock.me.uk or the North York Moors National Park Authority on 01439 770657. Further information on York Astronomical Society can be found at www.yorkastro.org.uk

Finally, if it’s really dark skies your after, look no further than the Galloway Forest Park – which as walk was going to press was hoping to become the first official Dark Sky Park in the UK.

The park’s successful bid was announced on Monday the 16th November 2009 in the International Year of Astronomy – a massive achievement for the UK and the south West of Scotland. To find out more about the award, skygazing and walks in the park, visit the Forestry Commission’s website.

Top image credit: NASA, ESA, AURA/Caltech, Palomar Observatory. Read more about it here.

Lower image credit: Galloway Forest Park

Astronomy is the oldest of the sciences and people have been gazing at the night sky since before recorded history – but it’s only relatively recently that we have had something more than the unaided eye to help us. When Galileo first turned his telescope to the night sky in the early 17th century he witnessed sights for the first time that, up to then, had been hidden from human view.

Yet although telescopes can indeed reveal many wonders in the night sky, we can spend hours stargazing with nothing more than the unaided eye to help us. On a clear and moonless night we can usually see up to 3,000 or so stars without optical aid. Unfortunately, due to street lighting and other forms of light pollution, many of us need to travel outside the cities and towns in order to witness a truly dark sky. Thankfully, walkers often find themselves located well away from city lights and so are able to witness dark skies as they are meant to be seen.

If you take a little time to look around the night sky you’ll notice that, amongst what at first appears to be a jumble of stars, patterns seem to emerge and the sky takes on a semblance of order. Many of these star patterns were described and charted by astronomers thousands of years ago and the star charts and maps of today contain many of the constellations devised by the ancients.

One of the most famous and easily-recognisable star patterns is the Plough, which is easily located lying low in the northern sky during November and December evenings. Shaped rather like a gigantic heavenly spoon the Plough is actually one part of a much larger constellation called Ursa Major, or the Great Bear, although the other stars in the Great Bear are all comparatively faint. The Plough itself, however – which marks the hind quarters and tail of the bear – stands out quite well.

While you’re looking at the Plough, check out the star in the middle of the Plough ‘handle’. You will see that this is actually a pair of stars comprising Mizar – the brighter of the two – and a nearby companion star, Alcor. Both Alcor and Mizar can be made out individually if you have keen eyesight and the sky is really dark and clear, but binoculars may be needed to bring the pair out well. If you have powerful binoculars, or a small telescope, you may see another, much fainter, star, forming a triangle with Alcor and Mizar. This star bears the somewhat-clumsy name of Sidus Ludovicianum and was named by the eccentric German astronomer Johann Georg Liebknecht in 1723. Spotting the star in his telescope and thinking he had discovered a new planet, he named it after his sovereign and patron the Landgrave Ludwig of Hessen-Darmstadt. The discovery was erroneous, but the name stuck!

The winter evenings are fairly chilly, but why not brave the elements and venture outside to seek out the celestial Plough? Happy stargazing!

To the uninitiated, the idea of deliberately stepping out into the night may seem a little daunting or absurd. But if you choose your location carefully and heed the weather forecast, you can enjoy a magical, moonlit wander that is a truly unique walking experience. Jeffrey Goddard is a seasoned nocturnal rambler whose first outing was back in the 1980s with Penwith and Kerrier Ramblers in Cornwall. For some years they organised a Midsummer’s Night walk along the ancient Tinners Way from St Ives, finishing with breakfast at a pub in St Just before the coach back to the start.

“It’s best if you have a totally clear, dry night,” he says, “and try to plot a route well away from artificial light. Before long, you will be mesmerised by both the moonlight and the galaxies that stretch across the entire night sky.”

Jeffrey cautions that even if you think you know a route quite well, it all looks and feels very different at night. Walking in the dark sharpens your other senses – especially hearing – so that you begin to notice all kinds of weird and wonderful sounds, he says. “There’s a silence and stillness that is quite extraordinary. However, I would say that if you are of a particularly nervous disposition night-walking may not be for you – there are lots of nocturnal creatures and insects out there that are likely to surprise you!”

Whether it’s badgers or owls, bats or glow-worms, the natural world has a completely different turn out at night, but you will have to tune your ears to detect some of them. One particularly memorable experience is much easier to hear, though: the Dawn Chorus – when songbirds such as blackbirds, robins, wrens, warblers and thrushes take turns to usher in the new day – is at its peak each May and starts as early as 4am.

Practicalities
So what are the main points to bear in mind if you’re going to walk through the night? First, however bright the moon might be shining, your route will look and feel very different in the dark, so it’s a good idea to familiarise yourself with it beforehand. Walking it during the day will allow you to note any potential problems, whether it be uneven terrain, difficult stiles or navigational issues. Your eyes will lose their night vision for anything up to an hour if you have to keep turning on a strong torch to read a map or find the way, so unless you choose to walk by torchlight, try to memorise your route beforehand.

Second, avoid obvious dangers such as crags or cliffs, and try to steer clear of particularly boggy stretches that might not be evident in the dark. Consider likely escape routes and draw up a routecard, leaving a copy with someone at home so they know where you’re going and when you’re due back. As you would with a daytime walk, aim to finish with suitable refreshment – but this time it’ll be breakfast instead of a pub lunch or supper!

In terms of what to pack, make sure you have plenty of provisions (including a hot drink) and sufficient warm clothing, since the temperature can drop considerably at night at almost any time of year. Even if the forecast is good, overnight dew can make the ground damp, so a lightweight waterproof or sit-mat is a useful item of kit. And every member of your party should have a torch (a head torch is probably the most useful type) but how often you use it is down to you.

Rural or urban?
So if you’ve never tried navigating by the stars or exploring a landscape by the light of the moon, what’s the best arena for a night-time adventure: rural or urban? The countryside is certainly as peaceful and tranquil as it is in daylight but, crucially, you can also escape the light pollution that blights so many built-up areas (see box, far right). In true darkness, a star-studded sky will really come to life – and it will also heighten your other senses to the sounds and smells of the natural world. Since midnight ramblers are not exactly common in the countryside, it’s sensible to avoid going too close to habitation, such as isolated farms and hamlets. And if you are in a group, keep the noise levels low – people tend to become suspicious of anyone outdoors at night.

Of course there are obvious safety factors to consider, such as avoiding cliff edges and other steep drops, as well as wet or dangerous ground. Opt for easy, uncomplicated terrain like open parkland or chalk downs instead of dense woodland. The gentle, grassy slopes of the Lincolnshire Wolds, Chilterns or South Downs are ideal locations, where the chalk paths can even act as a luminous guide in the moonlight. Or try wide, straightforward trails such as the Peddars Way, sections of the Heart of England Way or Cotswold Way. This is one occasion where you don’t need to head for the most remote parts of Britain to enjoy an exciting walk.

Night-walking in an urban setting is inevitably very different to going out into the countryside after dark. It is likely to be wholly or partly illuminated, of course, which makes navigating much easier. But the effects of both artificial light and moonlight can also be extremely atmospheric and enchanting – a riverside stroll through a city at night is often a mesmerising experience. Take common-sense precautions regarding personal safety, such as carrying a mobile phone or personal alarm and research your route in advance. And if you’re at all worried, don’t go unaccompanied.

By using public transport you can create interesting linear routes, and soon you’ll find that midnight walks through city centres, historic squares, graveyards, parks etc, can be fun and full of interest. Indeed, towns and cities often look, sound and feel very different places at night-time when there are fewer people and less traffic about. Inua Ellams organises the so-called Midnight Run in London, which involves groups of people walking across the city in the small hours, enjoying the special feel of a metropolis at sleep.

“Depending where you go, London can be very peaceful at night, offering an incredible sense of space,” he says. “Most city centres are deserted from 8pm and I like the idea of going out and reclaiming the streets.” Inua is planning a Midnight Run in Manchester this autumn and another next year in Glasgow (for more details, email themidnightrun@googlemail.com).

Heaven and earth
If you’re really immersing yourself in the night-time experience and plan to navigate by the stars, you’ll need a clear sky and some basic knowledge of the heavens. To begin with, check the lunar calendar to find the dates of the full moons (the next are on 4 September, 4 October and 2 November). Then get the most accurate and up-to-the-minute weather forecast, because you’ll want a cloudless sky for as long as possible. If all this falls into place and you are standing in the dark gazing up at the firmament, do as explorers of old have done before you and locate Polaris (the North Star). An imaginary line drawn from this star to the nearest point on the horizon shows the direction north. Polaris is located in the constellation called Ursa Minor, but many of us will be more familiar with the likes of the Plough (in Ursa Major), which can act as a useful celestial signpost. Soon you will be plotting Cassiopeia (shaped like the letter ‘W’) as well as easy ones such as Orion’s Belt, and your walk in the dark will become even more rewarding as you hone your astronomical skills. Just remember to look down at the ground occasionally to check where you’re treading.

For more on night-walking, see the Autum 2009 issue of walk

Image: Fir0002/Flagstaffotos