Category Archives: Astronomy

Aurora borealis

Posted on April 6, 2016 | 18 comments

A couple of weeks ago my very good friend from Thessaloniki, Agni, returned from a trip to Finland and sent me these pictures of the Northen Lights, or to give it its correct scientific name, the Aurora Borealis. The Aurora occurs when streams of charged particles from the sun are driven out into space by the solar wind. They are largely deflected by the earths magnetic field but at the poles where the magnetic field is at it’s weakest they can enter the atmosphere and react with different gases, and different gases produce different colours. The most common colour is yellowy green which is generated by oxygen at a height of around 60 miles.

Despite being half Danish and spending nearly all my summer holidays, and some winter holidays, in Scandinavia, I’ve still never seen the Aurora, so I think these pictures are absolutely stunning. And it must have been totally jaw-dropping to see it for real so I’m now even more on a mission to go and see them for myself!

‘Aurora borealis‘ means ‘dawn of the North’ and is named after the Roman goddess of the dawn, Aurora, and the corresponding Aurora in the Southern Hemisphere is called the ‘Aurora australis‘ or ‘dawn of the South’.

I don’t normally post other peoples pictures here but these are so special they have to be shared, so I’m really grateful to Agni for letting me post them. They were taken with a Nikon D3200 on a tripod with a 10s exposure time. And they’re so cool!

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Posted in Astronomy, Atmospheric phenomena

Tagged Aurora australis, Aurora Borealis, dawn of the North, dawn of the South, Finland, Northern lights, sky at night, solar wind, Southern lights

When the sun stood still

Posted on November 6, 2013 | 17 comments

The plane through the centre of the earth and the sun is called the ‘ecliptic‘ and it describes the apparent path of the sun around the earth. And the plane through the centre of the earth – on the earth’s equator – is called the ‘celestial equator‘. There is an angle between these two planes of 23.4^o and this angle is known as the ‘obliquity of the ecliptic‘.

It is the obliquity of the ecliptic which gives rise to our seasons, because as the earth moves around the sun a point on the surface will be closer to the sun in summer and further away in winter. The mid winter and mid summer solstices are the midpoints of those two seasons and at the midsummer solstice the perceived height of the sun in the sky is at its maximum ‘declination‘ – the angle between the ecliptic and the orbital plane. So whereas the solstices occur when the angle is at its maximum 23.4^o, the vernal and autumnal equinoxes occur when the angle between the two planes is at its minimum, i.e. 0^o, or when the celestial equator intersects with the ecliptic.

The summer solstice occurs in the northern hemisphere on June 21st and on this years solstice I found myself walking in the countryside late into the evening. It was a proper midusmmer day; sunny, warm and sultry, and the fields were full of wild flowers.

Field poppy – papaver rhoeas -my all time favourite wild flower. There’s nothing quite so spectacular as a field full of red poppies!

The field poppy is also known as the ‘Flanders poppy’ from the battle fields of WW1 – which seems wholely appropriate as I’m writing this on Remembrance Sunday. I find it difficult to photograph poppies and get the colours just right, but I really like these flowers against the green background. They were snapped in the field below, which was a riot of floral colour throughout the summer:

Looking along the drainage ditch which divides two arable fields

The old oak tree in this picture was home to a barn owl nest this year and I spent several evenings sitting in the undergrowth watching the toing and froing of the adults bringing prey to the nest. I didn’t get to see the fledglings but I’m hoping they were successful and return next year. And it was along this stretch of ditch where I photographed the yellowhammer, linnet and whitethroat I posted recently.

Not quite sunset, but the colours were breathtaking

And of course at that time of year, late in the day when the sun is getting low in the sky, the skyscapes can be magnificent .

Another flower which was sprouting in the hedgerows was woody nightshade, Solanum dulcamara, which is closely related to deadly nightshade, and the potato which is rather less toxic than it’s relatives – unless the potatos are green when they contain the same toxin. So don’t eat the green ones (or nightshade berries)!

Woody nightshade flowers with a dog rose in the background

Toward the end of my stroll it was getting darker and in the midst of a line of imposing horse chestnut trees is this dead one silhouetted against the crepuscular blueness of the western sky after sunset.

On another dead tree stump adjacent to this one was a kestrel eating its prey and it let me stand close by and watch it for several minutes which was remarkable in itself, but to give you an idea of how close I was I could actually hear it tearing the flesh off the bone! He must have been very hungry.

The moon emerging from behind a horse chestnut tree

And right at the end of the walk it was night time proper, and on midsummers day this year there was also a full moon.

The word ‘solstice‘ is derived from the Latin for ‘the sun stands still’ because the sun has stopped rising in the sky and begins it’s journey back across the ecliptic to bring summer to the southern hemisphere, leaving winter for us in the north. But I wasn’t thinking about that as I soaked up the summer warmth on midsummers day.

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Posted in Astronomy, Birds, Birds of prey, Countryside walks, Flora and fungi, Migrants, Ornithology, Owls, Songbirds, UK wildlife, Walks around Cambridge and Histon, Wild flowers

Tagged celestial equator, declination, ecliptic, field poppy, green potatos, midsummers day, seasons, solstice, wild flowers, woody nightshade

Early morning duck walk 22/01/2011

Posted on January 22, 2011 | Leave a comment

Before I sally forth on my intended theme for this post, and continuing the astronomical precedent from my earlier post where I included a picture of the recent partial solar eclipse, I want to share a picture of the moon I took last week. At this time of year opportunities for wildlife photography in the evenings are severely limited. But on Tuesday and Wednesday (18th and 19th January) the moon looked spectacular early in the evening when it was low in the eastern sky, and also very early in the morning, around dawn, when it was low in the western sky. So on Tuesday I rushed home from work, grabbed my camera and headed out the door with the dog in tow to try some lunar photography. I think the moon is an amazing thing and I can’t resist the opportunity to photograph it, and this is what I got:

Full moon low in the eastern sky around 6pm on 18th January, 2011 (f5.6, 1/800, ISO 800, 300mm)

After my lunar digression, and as alluded to in my post ‘Avian East Anglia’ I have been out taking a look at the bird life at Milton Country Park. I set off with my friend just after 8am on a very cold grey Saturday morning, which became progressively colder, greyer and rainy as time went by. Consequently I was less than hopeful of seeing much in the way of wildlife.

My fears of a fruitless walk at the Country Park were unfounded. As we entered the park a great spotted woodpecker (Dendrocopos major) was making plenty of noise high in a tree and during the walk we saw two and heard at least two others. I don’t usually use a spotting scope but my friend, David, has one and it really does enable some terrific close up views of distant creatures. We viewed a great spotted woodpecker at the top of a tall tree a good 100m away and the scope brought it right up close. I may add one to my next Christmas list.

A distant great spotted woodpecker – if only I could digiscope! This one wasn’t taken on Saturday… but it was at Milton Country Park

A cock bullfinch (Pyrrhula pyrrhula) was busy feeding in some bushes at the edge of a lake and plenty of blue tits (Cyanistes caerulius) and great tits (Parus major) were to be seen. A brood of six last years mute swan cygnets (Cygnus olor) were communing in a quiet corner of a lake:

One of six mute swan cygnets

And a pair of adult mute swans were on the slipway into an adjacent lake. A flock of mixed gulls consisting predominantly of black headed gulls (Larus ridibundus) with a single common gull (Larus canus) in their midst shared a flooded field on the edge of the Park with a flock of 57 lapwing. The lapwing would take to the air periodically and fly circuits round the Park before settling down again and each time they rose there seemed to be more of them, but a final count on the ground came to 57. I was pleased to see this number as I rarely see flocks of lapwing greater than 20 individuals.

Coot (Fulica atra), cormorant (Phalacrocorax carbo), a moorhen (Gallinula chloropus) and a lone kingfisher (Alcedo atthis) made appearances but the stars of the day were the various duck species. I like ducks and it’s always good to see more than just mallard:

Male tufted duck resplendent against the oleaginous steely grey-blue of the water in the early morning

Note the prominent tuft and the yellow eye of the tufted duck (Aythya fuligula) above. It was tricky to get good quality images due to the low light of the murky early morning. I opened up my lens (Nikon 70-300mm VR2 zoom) to f5.6 and was using a shutter speed of 1/80s at 300mm zoom. The ISO was set to 800 to cope with the light hence the slightly grainy look.

A flock of approximately 20-30 shoveler (Anas clypeata) were feeding on the same lake as the tufted duck:

Small group of shoveler – see the splendid beak of the male in the background (top) and in the foreground (lower)

Shoveler diet consists of small insects, molluscs, crustaceans, seeds etc. which they filter from the water with huge spatulate beaks by sweeping the beak from side to side with their whole head underwater whilst swimming round in tight circles. They come up for air only very briefly which meant I had to take quite a few pictures before getting one with the beak visible. Beatiful birds, I like these.

Several small groups of wigeon (Anas penelope) and gadwall (Anas strepera) mingled with the other water birds such as the numerous coot, gulls and cormorant.

A coot in the foregound with a pair of gadwall close by and a pair of wigeon in the background

By the end of our walk I was frozen but it was well worth braving the cold to see such a diverse range of birdlife. I shall return there on a sunny morning to try and get some less grainy photographs!

New Year Nature

Posted on January 6, 2011 | 1 comment

The most spectacular natural phenomenon to occur over the New Year period was, in my opinion, the partial eclipse on the morning of Tuesday 4th January. It commenced before daybreak in the orient and by the time the sun rose in the UK it was well underway. A very early-morning glance through the curtains in Histon suggested the cloud cover would scupper any attempts to view it from here. The eclipse was due to complete around 9.30am and with an immense stroke of good fortune the clouds parted to reveal a blazing sun low in the eastern sky at 9.05 so I ran around the house trying to find a suitable eye shield to view it through. Grabbing the chance of a breakfast time chocolate feast my daughter suggested cellophane wrappers peeled from some leftover Christmas confectionery, a stroke of genius on two levels. Alas, by the time there were sufficient to enable safe viewing, the image was so blurred as to be useless. So I rapidly retrieved some old photographic negatives from the attic and several layers of these provided an excellent filter for the purpose. We saw the partially occluded sun and I even managed to fire off a couple of photographs, so here’s the best one:

Partial solar eclipse at 9.15am on Tuesday 4th
January 2011 from Cambridge UK.

In terms of wildlife there have been a few highlights in the last week. I spent most of my walking time around Guns Lane and Abbey Farm north of Histon and the field to the west of the Lane, lying between it and Abbey Farm, known locally as ‘Rowleys Meadow’, is turning out to be a real treasure trove. A pair of kestrels (Falco tinnunculus) are in residence, usually found in the top of a tree which appeared in my ‘Guns Lane‘ post from the end of November last year.

Kestrel pair are regularly seen at the top of this particular
tree. The top one is a male and the lower individual a female.

A buzzard (Buteo buteo) has also been in the vicinity at least since New Years Day when it flew low over the meadow heading east and was spotted again on the 3rd perched in a tree further north along the Lane. I spent several minutes slowly working my way along the hedge to get into position for a photograph when a pair of mountain bikes coming the other way flushed it out. I’ll have to wait for my shot of a perching buzzard.

…so here it is making its exit with a fieldfare lurking in the bush bottom right

The most exciting encounter with a bird prey occurred on New Years Day whilst heading back from walking the dog in the Histon Fields. An orchard opposite my house has been home to flocks of redwing (Turdus iliacus) and fieldfare (Turdus pilaris) for most of the Christmas holiday. Approaching home at the end of our walk a female sparrowhawk (Accipiter nisus) approached at very high speed around 8 feet from the ground entering the orchard like a feathery Exocet! To be followed a split second later by a chorus of alarm calls as what seemed like hundreds of redwing scattered in all directions. I couldn’t see if she was rewarded with a meal.

Bullfinch (Pyrrhula pyrrhula) continue to maintain a presence on the lane, three individuals consisting of two males and a female provided a splash of colour in the tree tops on a grey day last week, and I flushed out a pair low down from a hedge further along the Lane. Flocks of long tailed tits (Aegithalos caudatus) are often chasing each other along the hedge and several days ago were accompanied by either a goldcrest (Regulus regulus) or firecrest (Regulus ignicapilla). It was most likely a goldcrest as firecrest are considerably more scarce and goldcrest are often found amongst flocks of tits. It was too close to focus binoculars on and the light was too murky to see the colours properly, so I couldn’t confirm the identity, but I’ll be keeping my eyes peeled in the hope of seeing it again.

Other species I see on most of my trips along the lane include a pair of green woodpecker (Picus viridis) , song thrush (Turdus philomelus), mistle thrush (Turdus viscivorus), redwing, fielfare and blackbird (Turdus merula)- five Turdus species which on several occasions have all been in the meadow at the same time.

Fieldfare in the top of a tree on Guns Lane

Waxwing (Bombycilla garrulus) continue to grace us with there presence. I’ve had a report from a colleague of a flock feeding on rowan berries on Kings Hedges Road, Cambridge, and my sister told me of a ‘treefull’ she’d spotted in a supermarket carpark in Kettering. Although a quick look in Garden Walk in Histon, where I saw them last week, suggested they may have moved on as there were none around and the trees and bushes had been virtually stripped clean of berries.

The heron (Ardea cinerea) is spotted around the north of Histon on a frequent basis, flying over and perched on numerous rooves including one behind my house which just happens to have a fishpond in the garden:

Grey heron sizing up a fishpond for an early morning raid in Normanton Way, Histon

It has some primary flight feathers missing on its left wing identifying it as the same one I posted about previously, feeding on pollock in my friends garden, then tapping on his window to ask for more.

Another friend of mine has reported sightings of blackcap (Sylvia atricapilla) and redpoll (Carduelis cabaret) in his garden in the last couple of weeks too. So there is a splendid variety of birdlife of all shapes and sizes to be seen now in a garden near you.