Shooting Stars, Meteors and the Perseids

The recent meteor shower  was a great celestial occasion for both viewing and photography. In this post I hope to explain what causes the ‘shooting star’ displays and illustrate how they appear to radiate from a particular point in the night sky.

I’ve been waiting for a clear sky on the peak night of the Perseids  for several years and this year provided me with the closest yet, almost 2 hours of clear sky with patchy moving cloud. So let’s start with a close-up picture of a shooting star.

A Perseid Meteor 40s f4 24mm ISO1600

Shooting star is a colloquial name for the trail of a meteoroid as it passes through our planet’s atmosphere. At this point it is more correctly called a meteor, if any fragment manages to meet the ground it will then be called a meteorite. Meteoroids are solid chunks of material moving through space with a size ranging from a spec of dust up to 10 meters across. When such an object enters Earth’s atmosphere, at speeds up to 40 miles per second, it heats up and usually disintegrates at about 30 miles of altitude. This fiery death happens in a mere second and is what we see from the ground. The colours seen in this display, can give scientists a clue about the composition of the meteor. In the picture above the blue/green suggests copper and the yellow/orange suggests sodium. If the brightness of a meteor in our skies is greater than that of the planets, then it is considered a fireball or bolide. We were lucky to see one such fireball last night, high in the north-east, above Dyfi Forest.

Perseid and Andromeda click image for a larger view …

The picture above shows a wider field of view, the Perseid meteor can be seen top left, whilst one of our neighbouring galaxies, Andromeda, may be seen in the bottom right. These images were taken using a Canon 5DMkII & 24-105L lens on a normal photographic tripod. With an exposure time of 40 seconds, this is long enough for the Earth’s motion to cause star trails, which are indeed very evident. To avoid this one could mount the camera on a German equatorial mount, as per the picture at the bottom of this blog post.

A meteor shower is said to happen when many meteors are seen in the sky over a short period of time and they all appear to radiate from the same point. This is caused by a stream of cosmic material colliding with Earth’s atmosphere. The Perseids are just one such stream of material. The comet Swift-Tuttle  travels through our solar system on a 130 year orbit, occasionally it loses matter and this is left as a stream of cosmic debris that our planet passes through in the fist half of august each year.

So why do the meteors in a shower appear to radiate from the same point and can we illustrate it?

Having been dropped by a speeding comet, all these cosmic dust particles are travelling in parallel with each other and at very similar velocities, perspective  vision demands that they appear to originate from the same point. For example, imagine you are standing in the middle of a long straight road. Far in the distance 2 motorbikes appear from the same point. In truth one is on the left of the road & one is on the right. As the motorbikes approach you, they will appear to diverge away from the same starting point and eventually one will pass one side of you and the other will pass the other side of you. The motorbikes have never moved apart, yet they appeared to originate from the same point. This is how it is with the meteors but on a much larger, cosmic scale.

The Perseids appear to radiate from a point in the constellation  of Perseus, hence the meteor shower’s name. To illustrate this I took the picture below:

Perseid Radiant click on image to view a larger version …

This was taken with a Canon 40D and 15mm f2.8 fisheye lens, mounted on an equatorial mount to avoid field rotation and star trailing. A series of 170 35-40 second images were taken sequentially. Satellite & aircraft trails were filtered out, as were cloud laden exposures. The remaining exposures were further filtered for meteor activity and then composited to form the above image. Six meteors can be seen streaking across the night sky. To the left one can see the Plough (Big Dipper) asterism ; to the right the constellations of Cassiopeia & Perseus can be seen. Each of the six meteors’ paths can be traced back to within the constellation of Perseus.

The orientation of the above image is looking directly north, over southern Snowdonia. Bottom left is Foel Crochan, Aberllefenni, with some cloud cover.

I hope you saw some meteors, if not, better luck next time. If you are hoping to photograph meteors, remember that the burst of light is typically only 1 second long and that’s what you’re trying to image. So use a fast lens and maximise the light gathering potential of your camera. Expose for long enough that the sky appears slightly brighter than black. Use a focal length of your choice, wider gives you more chance of catching one, longer may give you more detail.

Have fun.

Tranquil Waters

We’re lucky enough to have several RSPB  reserves locally; the nearest one being Ynys-Hir . I try to visit them as often as possible but probably don’t make as much use of them as I might. And I guess that’s what this post is about, a quick mention for Ynys-Hir to say how well worth a visit the reserve is.

Below is a picture that I took a couple of years ago, from the window of the Ynys Eidiol hide – presented as a scrollable panoramic:
(You’ll need either Quicktime or as I recommend the DevalVR plugin then just click the play button; try scrolling & fullscreen)

You can see another picture that I took of sunset from the Breakwater hide, Crimson Flight, over on my galleries.

By visiting Ynys-Hir not only will you have the opportunity to enjoy the landscape & nature of Mid-Wales but you’ll also be helping the RSPB to conserve this resource.

Dragon’s Eye

Lend me your imagination for a minute or two … I have here a photograph gained at much personal risk to the intrepid photographer (that would be me). It was necessary to approach this beast so close that it may have leapt upon me at any moment, the consequences of which, I dare not imagine. Here lay a creature from the depths of Wales’ Mythology. A creature that has stirred from the heart of the mountain.

What, I hear you say could this beast be? Was it breathing fire? No, but I fear that had I dwelled any longer, I may have joined the scorched grass that surrounded its lair. Without further ado I must post a small token view of my recent encounter:

Dragon's Eye

I think you can see the fiery lava within its eye, surrounding a deep blue-back pool at the eye’s centre; surely your soul could fall deep inside that eye.

Fear not, this beast did not need vanquishing by brave Knight & proud Steed. Read on to hear more and identify …

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“Brock” The Eurasian Badger (Meles meles)

The Eurasian Badger (Meles meles) is a shy nocturnal mammal; it is a member of the family Mustelidae. They are opportunistic omnivores who manage to survive on what their environment offers them; more on that later, here’s a picture:

_MG_6915-18Apr09-edit3   Click image for a larger view …

Adult badgers typically weigh 10 or 11 kg and are 75 to 90cm long with a moderate bushy tail of about 20cm. Their distinctive black & white face is easily recognised but sadly the only place that many people will see these beautiful creatures is dead at the side of the road, where many thousands are killed each year.

The UK has an estimated badger population of > 250,000. Badgers live in communal groups of up to 14 but more typically 7 or so. There is a dominant male (boar) who will protect the territory if necessary and one perhaps two breeding females (sows). The size of the territory depends upon the abundance of food but is typically ~200 acres. Badger dispersion is relatively low and contact between neighbouring groups is often low; the Badgers preferring to mark their territory with latrines and avoiding conflict where possible (conflict between rival boars can be quite violent). Preferred ground is woodland & permanent pasture with an abundance of earthworms, their main dietary component. Badgers do not hibernate but their activity levels may fall greatly in times of cold & hardship, at which point 2 or 3 may share a sleeping chamber for warmth.

The picture below of a badger about to squeeze under a fence line, clearly shows its bushy tail:

_MG_6927-23Apr09   Click image for a larger view …

Badgers have an extremely varied diet that follows availability in the different seasons. As previously noted, earthworms provide the bulk of their diet, this is why they pull up grass turf & dig through droppings. A Badger may consume as many as 200 earthworms in one night, indeed earthworms are thought to make up 50% of their diet. Other favourite foods include insects, beetles, berries, roots and nuts; these probably account for a further 40% of the Badger’s diet. If the opportunity arises a Badger may take small animals such as frogs or occasionally a rabbit, rats & hedgehogs may also be taken; these small creatures probably make up the final 10% of Brock’s diet. Other than man, badgers have no natural predators however wolves & bears may kill them in competition. Whilst many are killed on our roads, the main threats to the badger are urbanisation, intensive agriculture & persecution by humans. Badgers live in underground tunnels called ‘setts’ which may be over 100 years old. Human disturbance of a sett can be disastrous.

Badger-Diagram-1b   Click image for a larger view …

Setts are built up by successive generations of badgers. The main sett will be occupied all year around and consist of many meters of tunnels. Deep in the sett will be the breeding chamber where a sow will have her cubs. The chamber will be lined with bedding materials such as dry leaves or grass. It is often possible to see piles of old bedding outside the main sett entrance. The sett will also contain other sleeping chambers where the other community members can rest. Other subsidiary setts may be built around the territory and are most likely to be used when the sow has young cubs & wants peace in the main sett. In an old sett the main area can become quite complex & extensive; GPS readings from our local sett show that from bottom left to top right the sett covers some 57,000 sq. feet of surface. The 425ft length also covers quite a change in elevation, as the GPS profile below shows:

image

If possible badgers prefer to avoid heavy wet clay soils that are not easy to dig in or dry to lie in. A sloped, free draining woodland edge site with easy access to the forage of both grassland & woodland, is probably a Badger family’s ideal real estate.

_MG_0001-25Apr09-edit   Click image for a larger view …

Having mated in spring the sow delays implantation of the embryo for around 9 months. The actual gestation period is a short one of only 7 weeks and the young cubs are born in early spring. The cubs are born blind, often in a litter size of about 3. They are initially dependant upon the sow’s milk. After 6 weeks the cubs’ eyes are open and at 8 weeks they start to venture out from the sett. These first ventures are often in April / May. By 4 months old the cubs will have their full set of teeth and be foraging for themselves. It will take a year for the cubs to reach full maturity and less than half of them will make it.

If you’d like to watch badgers yourself, probably the easiest way is to join your local Badger group, there are many across the UK. You may also be lucky and have badgers that visit your garden to look for scraps; if so, a few peanuts will encourage them no end and you may soon be able to watch them from your house.

Badger Trail   Click image for a larger view …

Many people miss the signs of local badger activity, here are a few things to look out for:

  • Discarded Bedding
  • 5 toed footprints on worn paths
  • Dung heaps & latrines
  • Spoil heaps outside setts
  • Badger hair on fence lines

Below are pictures of a spoil heap and discarded bedding, click either one for a larger view:

Spoil Heap Discarded Bedding

Good luck with your watching; Badgers really are beautiful & fascinating creatures.

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Conservation at my home

It strikes me that I don’t post very much about my home patch. There’s lots that we can all do to help our planet, it’s flora & fauna. Whilst photographing, educating & evangelising is great, it is also important to ‘do our bit’; so what have we been doing, chez AnnMarie?

DSCF0461-20Jun08  Our Home, click image for a larger view …

We have about 50 acres of land in the heart of Dyfi forest, it comprises permanent pasture, river bank & deciduous woodland. We are bounded by river, forestry & SSSI. Our general goals are to maintain and if possible increase biodiversity. Here are some of the actions that we have taken so far:

  • Reduce artificial chemical use to a bare minimum
  • Plant new hedgerow
  • Plant new trees
  • Restore old hedgerow
  • Graze pasture in a manner that encourages flower seeding & protects sward
  • Leave areas of rough pasture over winter for insect cover
  • Designate a specific area ‘flood plain’ & manage to encourage plant diversity
  • Keep livestock out of woods to encourage young saplings & woodland floor plants
  • Maintain quiet backwater for amphibians to breed in
  • Leave some fallen timber for invertebrate & fungal habitat
  • Establish several bird feeding stations
  • Fence off sections of river bank to allow re-establishment of bank cover for riverside mammals
  • Encourage & feed wild mammals, as practical
  • Develop garden with wildlife friendly plants & technique, see RSPB website and Wildlife Gardener.

Autumn Twists   click image for a larger view …

The general thinking is to work in harmony with nature, not against it. The region is particularly rich in fungi and we also have a good selection of lichens. Some of the lichens are quite rare & are very sensitive to pollution, so great care is taken not to endanger them.

Not only can one help wildlife in this way but there are also lots of personal gains to be enjoyed, for example:

  • Its a fantastic place to bring up our daughter
  • The dawn chorus is wonderful
  • You’re never alone with all the wildlife around
  • We probably get fitter & healthier doing all this
  • Why not beautify your surroundings with plants & wildlife
  • It helps broaden our understanding of nature
  • Its just good fun

There’s more that we can & hope to do, but it all takes time & resources; it also pays to go steady & learn the lessons as you go. Here are some of the things still on our wish list:

  • Provide additional nesting places for a variety of birds & insects
  • Plant / restore more trees & hedgerow
  • Increase availability of water / bog habitat
  • Provide further butterfly habitat

I hope that this has given you an idea of what I might be doing when not behind the camera or computer. Perhaps its even inspired you a little.

 

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