Glancing from the window early on Thursday morning (00:48 BST) I was confronted with a beautiful, and equally mind bending atmospheric display as noctilucent clouds streaked there way across the northern sky. These elusive clouds, which consist of water ice crystals some 0.1 micron in diameter, are found in a tenuous atmospheric layer known as the mesosphere. Illuminated by sunlight from below the horizon, which is scattered by the ice crystals, they become visible; appearing to glow with a ghostly pale blue colour.
It was a truly mesmerizing sight that almost begged belief. I feel very lucky to have finally observed, and photographed these ‘wraith’ clouds. Hopefully the next few months will yield similar if not better conditions!
Noctilucent clouds sweep across the constellations of Auriga, and Perseus. Capella can be seen shining brightly towards the lower left hand corner, while Mirphak, and Delta Persei can be seen in the upper right hand corner.
The constellation Auriga disappears behind a rippling swathe of vivid Type 5 IIIb NCLs, while the outer arm of a large cumulus cloud begins to drift over the sky.
The incredible, and intricate detail in the wave like structure of these ethereal clouds can be seen here as they outshine the bright star Capella.
A firey red Sun casts it’s light on to a large cumulus cloud as it drifts over the roof tops. At the same time some fainter NCLs spread their glowing arms across the sky leading to a very surreal scene.
Tags: Auriga, Capella, DSLR, Mirphak, Noctilucent Cloud, Perseus
Posted in Astrophotography, Observing | 5 Comments »
The Moon is, and always has been a favourite observing target of mine. So when last weekend (30.05.09) brought some beautiful clear skies with it; I took the opportunity to explore some new lunar locations as well as revisit some old ones. There was so much to see that I couldn’t possibly fit it all into this blog post. However two features that really stood out for me were: Rima Ariadaeus, and Rima Hyginus; both impressive rilles that lie near the west coast of the Mare Tranquillitatis.
The word rille is used to describe the various depressions, or trenches that can be seen scarring the surface of the Moon. The term was used by early observers to characterize such lunar objects, and was probably introduced by the German astronomer Johann Schröter in about 1800. More recently the latin word rima (meaning fissure) is often used interchangeably with the word rille to describe the same kind of feature.
Rilles can be divided into three categories: linear, arcuate, and sinuous. Those of the first type are thought to be grabens: extended slabs of crust that have collapsed between parallel faults. They are comparatively straight, flat-floored, and are sometimes associated with crater chains. In comparison arcuate rilles have smooth curves, and are often observed near the edges of the lunar maria. They are believed to have formed when the lava that established the maria cooled, contracted, and sank. The sinuous variety seem to be similar to the channels that lava flows on Earth produce, but these lunar valleys are far more rambling; perhaps because the ancient lavas that spread across the Moon were more fluid than those found on Earth.
The shadowy laceration of Rima Ariadaeus, a 300 Km long graben, offered a wonderful view through the six inch refractor. At around 3.85 to 3.2 billion years old this lunar fault formed some time between the late, or early Imbrian epochs. A violent period characterized by colossal impacts, and vast volcanic eruptions that formed the lunar maria that we see today.
Conversely Rima Hyginus proved just a little harder to find, but only because I had chosen to look for it when low light conditions were not at there optimum. This hybrid rille, also an Imbrian formation, evolved through a fault that was subsequently altered by volcanic activity. Closer inspection of this lunar feature reveals that it ramifies by adjoining Rima Ariadaeus via a shallow groove towards the north east.
Both of these rilles made for wonderful viewing, and testify to the Moon’s tumultous past. So if you haven’t done so already I would thoroughly recommend that you take in an observation of these two fascinating lunar objects. A minimum aperture of around 90mm is almost certainly needed, and I would advise searching for them both around six days after a new Moon, or five days after a full Moon. Just be careful that you don’t get stuck in a groove!
Tags: Celestron Omni XLT 120, Mare Tranquillitatis, Moon, Rilles, Rima Ariadaeus, Rima Hyginus
Posted in Astro Art, Observing | 2 Comments »
I began a short observing session last Tuesday morning (12.05.09) by trying to split the well known double star Izar (also known as Epsilon Boötis) in the constellation of Boötes. Despite a hazy mist in the upper atmosphere conditions were fairly decent, but try as I might I just couldn’t separate the orange giant primary, and it’s smaller main sequence companion from each other. I was sure that a power of 166x would be up to the job, but obviously it wasn’t so perhaps someone can offer a little advice on the subject?
After about twenty minutes of fruitless scrutiny I decided to move on from Boötes to bathe in the radiance of my second morning target: Cor Caroli in Canes Venatici. The view through the 6mm plössl was delightful, but unexpectedly, and quite oddly the brighter A class primary shone with a greenish hue rather than the white or pale blue luminosity that I was anticipating. The secondary which is an F class star should have displayed a yellow iridesence, but instead showed no sign of colour.
Regardless of the perculiar spectral colours that I percieved this really was an attractive binary system to study, but I think it will be one that I will return to quite soon for a follow up observation.
Tags: Alpha Canum Venaticorum, Bootes, Canes Venatici, Cor Caroli, Double Star, Epsilon Boötis, Izar
Posted in Astro Art, Observing | 3 Comments »
Ever since @RevAaron over at Caffeinated Astronomy published a great post about observing the dwarf planet Ceres I have promised myself that I would spend some time tracking it down. Unfortunately up until now I have just never taken the opportunity to actually get around to doing it, but all of that changed at the beginning of last week.
Monday (11.05.09) brought with it the first of what would become four days of good weather; so before Ceres disappears below the western horizon in the next few months I thought I’d finally make the effort, and take in a view of this unique planetary object.
Visually Ceres resembles nothing more than a star even in the biggest of amateur instruments so it is worth doing your homework before you embark on an observation of it. Thankfully I had the help of some good twitter friends: @TaviGreiner @craiggold, and @LouisS who provided links to The Royal Astronomical Society of New Zealand, The Royal Astronomical Society of Canada, and Heavens Above (which I have to admit I’d completely forgotten about) to aid me in my hunt.
Locating Ceres actually proved easier than I thought it would be, and for the next 45 minutes I found myself glued to the 25×100 binoculars as I followed this bantam planet across the sky. This really was an enjoyable observation, and my thoughts began to run riot as I visualized how this diminutive world must look. It’s amazing to think that despite the exceptional efforts of the Hubble Space Telescope, and the Keck Telescope only 11 surface features have been identified; presumably some are craters, but the characteristics of most of them are still unknown. NASA’s Dawn Mission will shed more light on this mysterious world when it arrives there in 2015, but until then we will have to settle for an Earth based view, and a little imagination.
If you have not done so yet; then I encourage you to spend an evening in the company of Ceres. It may not be the most dazzling planetary object you’ll ever see, but once you’ve observed it you will be able to say that you have seen the smallest known dwarf planet in the solar system.
Tags: 1 Ceres, Dwarf Planet, Strathspey 25x100
Posted in Astro Art, Observing | 2 Comments »
Skirting the western shore of the Mare Nectaris you will find three fascinating craters: Theophilus, Cyrillus and Catharina — all of which beautifully illustrate the evolution of lunar geomorphology caused by impact erosion. Turning the Celestron Omni 120 here last week (30.04.09) really was a treat, and left me in no doubt about what I’ve been missing out on since I returned to amateur astronomy. The view just blew me away, and I spent the next hour picking my way across the wreckage of this ancient landscape. See here for details: www.lpod.org
Theophilus was the first of my targets, and the youngest of the crater trio which formed some time around the Eratostherian period. While the four jagged peaks of the impressive central mountain were clearly defined it was the intricate detail in, and around the robust terraced walls that caught my eye. The contorted ridges that I could see radiated away from the smooth crater floor like ripples in a pool of water, and made for an exceptional observation.
Lying to the south west, and slightly overlapped by Theophilus in the north east, the soft but tortured outline of Cyrillus marked itself out against the surface. This lunar relic dates from the earlier Nectarian period when the Moon was battered by massive impacts that created the major lunar basins. Looking within Cyrillus itself the three imposing mountains that rise around one kilometer from the floor of the crater stood out prominently, while the shadow filled Cyrillus A clung to the deteriorating south west verge. At this point I took a moment to examine Cyrillus’ wall’s and noted the state of deterioration, but it was nothing compared to Catharina’s decimated appearance.
An irregular, and ruinous formation; Catharina presented itself in all it’s ramshackle glory not far from Cyrillus. This crater was also formed around the Nectarian period, but it was clear to see that it had suffered extensive damage from further impacts. The shadowy veil of Catharina P made a bold impression where it had obliterated the northern wall, while little remained of the crater embankment to the north east where Catharina B, and G had impacted. Casting my gaze towards the southern interior I easily spotted the dark silhouette of Catharina S watching over the remains of the crumbling rampart, while the shadowy outline of Catharina C embedded itself into the outer exterior of the crater.
There is so much detail to be had from this region of the Moon that it will keep you coming back again, and again. If you want to study a good example of crater degradation then this trio will not disappoint. All are visible with 10×50 binoculars, and personally speaking I have had some pretty good views through my 25×100 binoculars. However for seriously good observations a telescope in the region of 90mm, and above will be needed.
To see Theophilus, Cyrillus and Catharina at their best I would recommend observing them when the Moon is either four to six days old, or when it is nineteen to twenty one days old. So make sure you mark those times in your diary, and be sure to get out and take a good look at this display of “beautiful devastation”.
Tags: Catharina, Catharina B, Catharina C, Catharina G, Catharina P, Catharina S, Celestron Omni XLT 120, Cyrillus, Cyrillus A, Eratostherian, Mare Nectaris, Moon, Nectarian, Theophilus
Posted in Observing | 2 Comments »