June 2011 – The Amazing Sky

June 28, 2011June 29, 2011

The Glowing Clouds of Solstice Appear

The glowing clouds of solstice have appeared. This was my first sighting of “noctilucent clouds” for the season.

Every northern summer in late June and early July we are often treated to bright pearly clouds glowing along the northern horizon long after sunset. Their origin remains somewhat of a mystery. These clouds form almost at the edge of space, so high there shouldn’t be much for clouds to form around. But their height is what makes them visible, as they catch sunlight streaming over the pole even in the middle of the night.

I took this shot Tuesday, June 28 just before midnight. The noctilucent clouds are the blue-white wavy bands just above the orange twilight. In front of them lie dark normal clouds low in our troposphere. But the NLCs shine from an altitude of some 80 km, well into the mesosphere. They are located over the Northwest Territories but, like aurora, their height allows us to see them even from more southerly latitudes.

The bright star Capella, circumpolar from my latitude of 51° North, shines through the clouds at right.

June 26, 2011

Centaurus, Creator of Constellations

In George Lucas mythology, Luke Skywalker went to Yoda to learn the wisdom and ways of heroes. In Greek mythology, heroes the likes of Achilles, Jason and Hercules sought out Chiron, the wise and kindly Centaur, who taught them science, astronomy, medicine, music, arts, hunting and archery.

Centaurs, the romping half man/half horse creatures, were a riotous and drunken lot, but not immortal Chiron. He was the offspring of Kronos and the ocean nymph Philyra and served as tutors to many legendary heroes. One reference in my library suggests Chiron actually invented the constellations, to make it easier for mankind to keep track of the stars and the season. To reward his work, Zeus placed Chiron in the stars, becoming by some accounts, this southern sky constellation, Centaurus.

However, most writings suggest Chiron is actually the Zodiac constellation of Sagittarius, while the constellation we call Centaurus is one of the wilder bunch, depicted in the sky as carrying the slain Lupus the wolf, drawn here in the fainter blue stars at top centre.

The bright stars at right are the main stars of Centaurus, including Alpha and Beta Centauri at lower right. Beta Centauri is the blue star, a giant some 390 light years away. But just to the left of Beta is yellow-white Alpha Centauri, a Sun-like star (or actually a pair of them orbiting each other) just 4.3 light years away.

Alpha and Beta Centauri sit at the start of a long dark rift in the Milky Way that splits into fingers of nebulosity reaching into Norma, Ara and Scorpius, here at the left edge of the frame.

I took this shot of Centaurus and Lupus in Chile last month, using a 50mm lens and a Canon 5D MkII. It’s a stack of four 6-minute exposures at f/4 and ISO 800, layered in with two exposures shot through a Kenko Softon-A filter to produce the photogenic star glows.

June 23, 2011

Summer Solstice Space Station, Part 2

Here’s a capture of the Space Station, coming over in a darker, clearer sky than last night’s shot (in the previous blog). This was June 22, 2011, a fine solstice night on the Canadian Prairies.

The time was just before midnight, with no Moon. Yet the sky is blue and the northern horizon tinged with the orange glow of twilight. It never gets truly dark now, as summer begins. To the right, on the northeast horizon, a low green aurora kicks up.

The Space Station, the dashed arc at top, tonight passed from west to southeast, across the southern sky at the top of this fisheye 360° frame.

This is a stack of 28 18-second exposures at f/4 and ISO 1600 with the Canon 5D MkII and Sigma 8mm lens.

June 22, 2011June 22, 2011

Summer Solstice Space Station

We’re currently enjoying a series of nightly (and often twice or thrice nightly) passes of the International Space Station, coinciding with the bright nights of summer solstice.

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I took this shot on the night of solstice, June 21, 2011, as the Space Station came directly overhead, flying out of the west then heading off into the east. So we’re looking a little west of north here, toward the bright northern horizon. Pity some light cloud hazed up the sky. The pass began at 11:12 pm so the sky was still quite bright, though even an hour or two later at this time of year the northern horizon is tinged with perpetual twilight glow, at least at my latitude of 51° N.

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To create the image I took a series of 100 3-second exposures (as long as the bright sky would allow) taken 1 second apart in rapid-fire fashion with the camera firing automatically with a remote timer. The 1 second gap between exposures creates the gaps in the Space Station trail.

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I processed the images in Adobe Camera Raw, and exported them all as TIFFs to their own folder. I then used Chris Schur’s excellent “Star Trails” Photoshop Action to stack all those images into one composite image showing the complete flight of the Space Station across the sky. A little application of Shadows and Highlights helped bring out the foreground and bright sky detail.

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I used the Sigma 8mm fisheye lens and Canon 5D Mk II to capture the whole sky, for a still and time-lapse sequence suitable for projection in a full-dome video planetarium … because the neat thing about this method is that the same set of images can be strung together sequentially (using Photoshop Extended’s Movie function) into a time-lapse movie of the pass, showing cloud and star motion as well as the ISS passage. The same techniques work for star trails, as indeed you can see here with the stars of the northern sky (Big Dipper at left and Cassiopeia at right) trailing around the North Star.

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June 18, 2011

The Moon in June

On one of the few clear nights of late I took the opportunity to shoot the Moon. It’s a familiar subject to be sure, but one I don’t shoot very often. Pity really, as it is rich in detail and makes for dramatic photos.

I took this shot June 12, about 4 days before the Full Moon of June, so this is a waxing gibbous Moon. Lots of terrain (lunain?) shows up at left along the terminator, including the wonderful semi-circular bay at about 10 o’clock called Sinus Iridum. At the bottom is the bright Tycho crater, with its distinctive splash of rays spreading out across most of globe. Imagine the devastating impact that caused that feature! It isn’t that old either — estimates suggest Tycho is just 100 million years old, putting its formation smack dab in the middle of the Cretaceous Period when dinosaurs ruled the Earth. They would have seen that impact, little knowing another similar-sized impact 35 million years hence, but aimed at Earth, would do them in.

For this shot I used the Astro-Physics 130mm apo refractor with a 2x Barlow lens to increase the effective focal length to 1600mm, a combo that exactly fills the frame of the Canon 7D with no room to spare. I processed this image for high contrast, to bring out the subtle tonal and colour variations in the dark lunar seas, an effect due to different mineral content of the lava that oozed out forming the lunar plains. Judicious use of Highlight Recovery (in Camera Raw) and Shadows and Highlights (in Photoshop) brings out the detail across a subject with a huge dynamic range in brightness. A liberal application of Smart Sharpening also helps snap up detail.

— Alan, June 18, 2011 / Image © Alan Dyer 2011

June 16, 2011June 16, 2011

Into the Heart of the Scorpion

Here we peer into the heart of Scorpius, to a place where the sky is painted with pastel hues unlike anywhere else in the heavens.

The yellow star at bottom is Antares, the cool supergiant star that marks the heart of the Scorpion. To the right is Messier 4, a globular cluster of thousands of stars. Wrapping the entire field are shrouds of dust, reflecting the yellow light of Antares and the blue light of hotter stars above, such as Rho Ophiuchi at top right. Glowing hydrogen gas clouds add the magenta hues.

The remarkable feature of this field are the dark fingers, clouds of dark interstellar stardust glowing with a dim yellowy-brown hue. In places the clouds become more opaque and intense, blocking any light from background stars. Those clouds must be close by in our galactic spiral arm because few stars lie between us and their dark masses. Estimates put them about 400 light years away.

The entire region is a busy factory of star making, one of the closest to our Sun. Chances are our solar system formed in a similar star factory 5 billion years ago, one that has long since dissolved away and dispersed around the Galaxy.

Like the previous shot, this is a Canon 7D/135mm telephoto image in a stack of six 2-minute exposures, taken from Chile in early May. I find it remarkable that with digital cameras just 2-minute exposures not only bring out the dark nebulas, but actually show them with colour and tonality. In the old days, film shots 20 minutes long only ever showed them as a mass of underexposed and featureless black.

June 16, 2011

Off the Stinger Stars of Scorpius

Off the tail of Scorpius lies one of the great starry regions of the Milky Way. From southern Canada the Scorpion’s Tail barely clears our horizon at this time of year, on June nights. But from farther south, Scorpius crawls high into the sky — and the sky actually gets dark at solstice, so stargazers can see the starclouds of Scorpius in all their glory.

At right, the blue stars mark the “stinger” at the end of the Scorpion’s tail. The brightest one, called Shaula, or Lambda Scorpii, is a hot blue giant star some 10,000 times more luminous than our own modest Sun. It is also a triple star, with another luminous blue star orbiting it, plus a third odd mystery star thought to be either a neutron star or perhaps a young proto-object still in the process of forming a proper “main-sequence” normal star.

To the left lie two prominent clusters of stars: at top the Butterfly Cluster (a.k.a. Messier 6), a bright group of stars sitting amid a dark bay of dust. Below it, almost lost in the stars, is Ptolemy’s Cluster (a.k.a. Messier 7), that is an obvious sight to the unaided eye – so obvious the Greek astronomer Ptolemy catalogued it in 130 AD. Several other star clusters pepper the field.

This telephoto lens shot frames the field as binoculars would show it. I took this from Chile in early May, using the Canon 7D and 135mm lens, for a stack of six 2-minute exposures at f/2.8 and ISO 1250.

June 7, 2011

A Window in the Stars

In this part of the sky the Milky Way takes on a surprising palette of hues. And it’s all due to dust.

The centrepiece of this shot is a bright star cloud in Sagittarius called, well, the Sagittarius Star Cloud! But not the Large one. This is the Small Sagittarius Star Cloud, a.k.a. Messier 24, a mass of stars with a single black eye. The dark spot, called Barnard 92, is a dense and opaque cloud of dust. Stardust — clouds of carbon soot blown out by aging stars — weaves all through this scene, creating the dark canyons winding through the stars. Obscuring dust also dims much of the background stars and discolours most of this part of the Milky Way a yellowish brown. It’s the same effect that dims the setting Sun a deep orange or red, as its light shines through haze and dust in the sky.

But here, the Star Cloud looks bluish and “cleaner.” That part of the Milky Way has less dust in front of it. And yet it is much farther away than the yellow dusty starfields around it. When we look toward the Small Sagittarius Star Cloud we are looking through a dust-free window, allowing us to see unencumbered right past our Galaxy’s nearby Sagittarius-Carina spiral arm to glimpse a dense part of the more distant Norma Arm, an inner spiral arm of our Milky Way Galaxy about 12,000 to 16,000 light years away.

To the lower right of M24 is M23, a rich cluster of stars 2,000 light years away, nearby by galactic standards, and so sits suspended in front of the fainter star background. The pinkish nebula at top is Messier 17, the Swan Nebula.

I took this shot May 2 from Chile, using the Canon 7D and 135 lens, for a stack of six 2-minute exposures.

June 5, 2011

Here Comes the Sun!

I can count on one hand how many shots of the Sun I’ve taken in the last decade that weren’t at an eclipse, or a sunrise/sunset. I just don’t do much solar shooting. But today I had to resurrect some old gear to get this shot. The Sun was putting on a fabulous show this afternoon (Sunday, June 5, 2011) with an army of huge prominences rimming the edge of the Sun. Very impressive. And looking very HOT!

After 2 to 3 years of record low activity, the Sun is picking up, returning to its normal self, with sunspots and prominences a daily occurrence. But these were especially dramatic. Each of these prominence “flames: towers tens of thousands of kilometre above the surface of the Sun. The Earth would be a dot next to one of them.

To get this shot, I created a masked composite in Photoshop of two exposures, a short 1/13s second shot to record the disk detail, and a long 1/2 second shot to record the fainter limb prominences. For a telescope I used my little Coronado PST H-alpha scope, a special scope just for solar viewing that filters out all but a narrow wavelength of red light, allowing the prominences to be seen.

Trouble is, my DSLR cameras won’t reach focus on the Coronado scope. So I dusted off the little 2003 vintage Sony DSC-V1 point and shoot camera and a Scopetronix 40mm eyepiece and “afocal” adapter, so the camera was screwed onto and looking into the eyepiece which was then inserted into the scope. I hadn’t used an afocal setup like that since the Venus transit in 2004.

It was tough to focus the stack, so focus was a bit of a guess — it was helped here with a liberal application of Photoshop’s Smart Sharpen filter! In all, it is a crude system but in a pinch it does work. Maybe I’ll have to get better gear just to take solar shots. With the Sun becoming more active, there certainly will be lots more to shoot.

June 5, 2011

Saturn Sidles Up to a Star

If you look up this week, to the southwest, you’ll see a bright star in the evening twilight that, upon close inspection, is really a tight double star. The fainter companion becomes obvious as it gets dark. The bright member of the pair is actually Saturn, and its fainter companion is the star Porrima, a.k.a. Gamma Virginis. And they are unusually close!

This week Saturn (at bottom here) sidles up to Porrima (at top), getting so close both are contained in a high-power telescope field, which is what this shot depicts. I took it Saturday night, June 4, when Saturn was about 1/4° (16 arc minutes) from Porrima. But by June 10 their separation will be a tad less, at 15 arc minutes apart. This week Saturn stops its annual retrograde motion just shy of Porrima.

The pairing made a wonderful sight in the telescope tonight, especially because of the “good seeing” — so Saturn looked very sharp. And Porrima, itself a very tight double star, was easy to split at 200x, appearing like a pair of headlights at high power. (The photo doesn’t split Porrima.)

But the nicest view is just naked eye — Saturn and Porrima are forming a rare and temporary double star easy to split with no optical aid but looking much more striking than any other naked eye double. The pairing won’t last long — Saturn turns around near Porrima this week, then begins to head east again away from its stellar partner.

The shot also picks up four of Saturn’s moons: Dione very close to Saturn, then Tethys, and Rhea in a row from left to right, and bright Titan below the trio.

This a stack of five 5-second exposures at ISO 1600 with a Canon 7D attached to my 130mm Astro-Physics refractor with a 2x Barlow, giving an effective focal length of about 1600mm and f/12. I took this in twilight to add the blue sky.

June 4, 2011

The Seven Sisters of the South

Down in the south sit many austral equivalents to namesake northern sky objects: the Southern Cross, the Southern Beehive, the Southern Pinwheel. This is the “Southern Pleiades,” a match to the famous Pleiades star cluster prominent in our northern hemisphere sky. Since our Pleiades also carries the moniker the “Seven Sisters,” I suppose that makes this object the “Seven Sisters of the South.”

The field here again duplicates what binoculars would show, and this is a lovely object for binos. Its resemblance to the northern Pleiades comes from this star cluster’s bright but scattered appearance, and the blue colour of its sorority of stars. Like its northern counterpart, the Southern Pleiades is a cluster of hot young stars which shine furiously blue in their energetic youth. This group is perhaps no more than 50 million years old, and like the northern Sisters, shines quite close by, just 480 light years away, putting it a stone’s throw away down our own galactic spiral arm.

Officially catalogued as IC 2602, and also dubbed the Theta Carinae Cluster, this clutch of blue stars shines just below the Carina Nebula (you can see both together in my earlier blog The Best Nebula in the Sky). A couple of other fainter star clusters also populate the field.

I took this shot with the Canon 7D and 135mm telephoto lens and stacked five 2-minute exposures. Stacking helps smooth out background noise, though in a wide field shot like this, the sheer number of stars tends to overwhelm any camera noise.

June 4, 2011

An Island in a Sea of Stars

This image looks toward the inner spiral arm of our Milky Way called the Norma Arm, where stars bunch together to form the rich Norma Starcloud, a prominent patch in the southern Milky Way. What you see here is all stars, lots and lots of stars.

Seemingly embedded in the sea of stars is an island of brighter stars called the Norma star cluster, or more prosaically NGC 6067. It’s about 6800 light years away, much closer to us than the more distant stars behind it. It is literally floating in front of the background sea of stars.

As with the previous image, this is a wide field shot, taken with the 135mm telephoto, to frame the field much as it would appear in binoculars. This shot is a stack of six 2-minute unguided exposures at ISO 1250 with the Canon 7D riding on the little Kenko tracking platform. It’s one of a couple of dozen fields I shot the first night of shooting on Chile in May.

June 3, 2011June 3, 2011

Rose of the Southern Sky

It’s been a month since my last post, a month with no new astrophotos from home. But I’ve got a backlog of RAW files to work through from the Chile trip a month ago. Here’s a new image from that shooting expedition. It’s of an area of the southern sky that lends itself to every focal length and framing variation — you can’t go wrong with the Carina Nebula!

This wonderful nebula in the deep-south Milky Way rewards any astrophotographer. For this shot I used a 135mm telephoto (Canon’s wonderful f/2 L-series lens) and the Canon 7D camera. The 7D is what I call a “stock” camera, used just as it comes off the dealer shelf. The 7D does a superb job capturing the red nebulosity and its faint outlying bits and pieces. It tends to record these clouds of glowing hydrogen as magenta in tone. By comparison, my other Canon camera is a “filter-modified” 5D MkII. You can see a shot of this same area of sky taken with the 5D MkII a few blogs back under The Best Nebula in the Sky, posted May 6. The 5D MkII’s modification (which replaces the filter in front of the sensor with a new astro-friendly one) allows it to record deep-red wavelengths and picks up more faint nebulosity, registering it more as red in tone. But both images look good and presentable.

This field is rich in objects — not only the main sprawling nebula but nearby star clusters and patches of dark dust clouds. It is one of the finest fields in the sky for binoculars, and this shot approximates the field of view of typical binos. I like to shoot a lot of objects with telephoto lenses — while the main subject is not frame-filling and in your face, it does match (at least in field of view) what you can see in binos, useful for illustrations and observing articles. Of course, the camera picks up more stuff and colours even your bino-aided eyes can’t see.

This shot is a stack of five 2-minute exposures at f/2.8 with the 135mm telephoto, on the Canon 7D at ISO 1250. I used the little Kenko Sky Memo tracking platform for this, letting it track without any added guiding. It’s tracking was spot on, with nary any star trailing as it followed the target for 20 minutes or so.