The Dark Clouds of Cygnus

Stare into the starfields of Cygnus and ponder what lies undiscovered in our part of the Milky Way.

You are looking down the spiral arm we live in, into clouds of stars seemingly packed together. Every one of those specks is a sun like ours. With planets? Very likely, as we now know.

Amid the stars float glowing red clouds of hydrogen gas. The North America Nebula shines at lower right.

Snaking northward from the “arctic” region of the bright nebula is a river of dust that broadens into a delta of dark nebulosity. Once thought to be holes in the sky allowing us to see deeper into space, we know now that these dark nebulas are really foreground dust clouds filled with the soot of dying stars, carbon dust that absorbs starlight and obscures the more distant parts of the Milky Way.

This dust cloud is called Le Gentil 3, named for the 18th century French astronomer who first noted its position in the sky. Le Gentil’s dust cloud is one of the easiest features of the summer Milky Way to see. Look north of Deneb, the bright star at the right of the image, and with the unaided eye on a dark moonless night you’ll see what looks like a dark hole in the Milky Way. That’s Le Gentil 3.

I use this dust cloud as a measure of sky brightness. On a truly dark night, Le Gentil 3 looks darker than any other area of sky, even relatively starless regions off the Milky Way. Most of the sky brightness we see from a dark site is really starlight. But Le Gentil’s proximity and opaqueness makes it appear darker than the more distant starlit sky background.

This image covers about the width of a binocular field. I shot it from the Cypress Hills in Saskatchewan this past weekend, using the Canon 5D MkII at ISO 1600 and Canon 135mm telephoto lens at f/2.8. It’s a stack of 10 five-minute exposures.

— Alan, August 22, 2012 / © 2012 Alan Dyer

A Cloud of Stars in Scutum

This is a binocular-sized gulp of sky in the northern summer Milky Way. Countless stars form a bright patch in the Milky Way called the Scutum Starcloud, named for the odd little constellation of Scutum the Shield that contains it.

Visible to the naked eye, this star cloud is a rich area for binoculars or a small telescope. One favourite object of stargazers lies embedded in the star cloud and can be seen here as a bright clump of stars at left of centre. That’s the Wild Duck Cluster, or Messier 11, a dense and populous cluster of stars within the already star-packed Scutum Starcloud. Look in this direction into the Milky Way and you are looking toward the next spiral arm in from ours, some 6,000 light years away.

The immensity of stars in just this small area of sky is hard to fathom. That’s why it’s called deep space!

– Alan, August 9, 2012 / © 2012 Alan Dyer


A River of Starlight and Dust


Look up on a dark summer night in the northern hemisphere and you see a river of stars flowing across the sky.

This is the Milky Way, a glowing mass of millions of distant stars populating the spiral arms of the Galaxy we live in. Lining the arms are lanes of dark interstellar dust, seen here splitting the Milky Way in two from the bright red North America Nebula at top, down to the core of the Galaxy in Sagittarius on the horizon. The dust is the soot created in stars and blown into space to form a new generation stars and planets.

This ultra-wide-angle scene takes in almost the entire summer Milky Way from the southern horizon to beyond the zenith overhead at top. I shot this a couple of nights ago from my rural backyard on a particularly transparent and dark night. It was heaven on Earth.

— Alan, July 26, 2012 / © @ 2012 Alan Dyer


The Rose of Winter

While I took this shot three weeks ago, I’ve only just got around to processing it. This is a nebula-filled region of the northern winter sky in the constellation of Monoceros, the unicorn.

The highlight is the rose-like Rosette Nebula at bottom, an interstellar flower of glowing hydrogen where new stars are forming. Above it, at centre, is a mass of pink, blue and deep red nebulosity that forms the Monoceros Complex. All lie in our local corner of the Milky Way, in a spiral arm fragment called the Orion Spur, a hotbed of star formation.

This field, shot with a 135mm telephoto lens, sits to the left of Orion and spans about a hand width at arm’s length. It would take a couple of binocular fields to contain it. Next on my astrophoto agenda – shooting some close ups of selected bits of Monoceros, shots that have eluded me till now.

— Alan, February 12, 2012 / © 2012 Alan Dyer

Celestial Pinks and Blues


Who says the dark night sky isn’t colourful? Of course, to the naked eye it mostly is, with the darkness punctuated only with a few red, yellow and blues stars. But expose a camera for long enough and all kinds of colour begins to appear.

This region is above us now, in the Northern Hemisphere evening sky for mid-winter. It’s the boundary area between Taurus and Perseus. Below are the vivid blues of the hot young Pleiades star cluster in Taurus. At top, just squeezing into the frame, is the shocking pink of the California Nebula, a glowing cloud of hydrogen gas in Perseus.

But between are the subtle hues of faint nebulosity weaving all through the Perseus-Taurus border zone. Below are faint cyans and blues from dust clouds reflecting the light of the Pleiades stars. In the middle are the yellow-browns of dark dust clouds hardly emitting light at all, but snaking across the frame to end in a complex of pink and blue straddling the border collectively known as IC 348 and IC 1333. At top, the glowing hydrogen gas of the California emits a mix of red and blue wavelengths, creating the hot pink tones, but fading to a deeper red to the left as the nebula thins out to the east. Throughout, hot blue stars pepper the sky and help illuminate the dust and gas clouds which will likely form more hot stars in the eons to come.

I took this shot last Wednesday night, on one of the few clear, haze-free nights of late. This is a “piggybacked shot,” with the Canon 5D MkII camera going along for the ride on one of my tracking mounts. This final shot is a stack of five 6-minute exposures, highly processed to bring out the faint clouds barely brighter than the sky itself. The camera was equipped with a 135mm telephoto lens, giving a field of view a couple of binocular fields wide. Hold out your hand and your outstretched palm would nicely cover  this area of sky. But only the camera reveals what is actually there.

— Alan, January 29, 2012 / Image © 2012 Alan Dyer

Milky Way Mosaic

Centre of the Milky Way Panorama (2011)

It’s taken me a few months to get around to the task, but at last! — my mosaic of the Milky Way I shot in Chile back in May.

The panorama is made up of 6 frames, stitched and blended together, extending from Crux, the Southern Cross (at right) to Aquila the eagle (at left) — a sweep of the Milky Way from Acrux to Altair! The mosaic is centred on the core of the Galaxy in Sagittarius and Scorpius.

Panoramas like this allow you to step back a distance and take in the big picture:

— You can see the large-scale structure of the dust clouds and the odd diagonal sweep of many of the clouds cutting across the plane of the Galaxy. I’ve never heard an explanation of why the dust lanes seem to have that structure and direction. I also see a 3D effect, with the nearby dust clouds hanging in front of and obscuring the bright starclouds of the distant inner spirals arms of our Galaxy.

— Also apparent are the extensive dust clouds at left extending from Ophiuchus (at top) down into Aquila, well below the plane of the Galaxy. Most wide-angle shots of the Milky Way I see tend to process out the subtle brown clouds that extend far off the Galactic plane. And they are brown, not black.

— And what really stands out is the band of bright blue stars from Scorpius (at top centre) to the right above the Milky Way through Lupus, Centaurus then down into Crux. This is a section of Gould’s Belt, a ring of hot blue stars around the sky that runs at an angle of about 20° to the Milky Way. This ring of hot, nearby stars surrounds us in our spiral arm and is thought to be only about 65 million years old, likely caused by some disturbance in our spiral arm which set off a wave of star formation close to us.

— And … as my Australian friends will point out, you can see the entire Dark Emu, made of the dust lanes from the Coal Sack in Crux at right (his head and beak), through the curving lanes in Centaurus (his neck), then sweeping up and over the centre of the Galaxy (his body) then down into Scutum and Aquila (his two feet and his tail).

I took this panorama from the Atacama Lodge in north central Chile, using the Canon 5D MkII and Canon 35mm lens. Each of the 6 segments that went into this pan was itself a stack of 4 x 6 minute exposures, plus a fifth exposure through a soft-focus filter, all at f/4 and ISO 800. The camera was on a Kenko SkyMemo tracking platform. I assembled the pan with Photoshop CS5’s Photomerge command. This is actually only half of the full panorama mosaic, which extends for another 5 segments to the right along the Milky Way to Orion, taking in the entire southern portion of the Milky Way. But this is the best bit!

— Alan, Oct 2, 2011 / Image © 2011 Alan Dyer

The Stellar Triangle of Summer

When the Summer Triangle sinks into the west, we know summer has come to an end. While the stars of the Summer Triangle are now high overhead from northern latitudes as the sky gets dark, by late evening the Summer Triangle is setting into the west.

These three bright stars are an example of stellar variety:

– At bottom is Altair in Aquila the eagle. It’s a white main-sequence star 17 light years away, fairly nearby by stellar standards. Leslie Nielson and his crew went to Altair in the 1950s movie Forbidden Planet.

– At top right is Vega, in Lyra the harp, a hotter and more luminous blue-white star than Altair, making it appear brighter than Altair, despite Vega being farther away, at 25 light years distant. Jodi Foster went to Vega in the movie Contact.

– But the third member of the Triangle, Deneb, at top left, is an extreme star. It appears a little fainter than Vega, but looks can be deceiving. Deneb is actually a luminous supergiant star, putting out 54,000 times the energy of our Sun. Deneb is about 1,400 light years away and yet, due to its fierce output of light, appears almost as bright as Vega. Light from Deneb left that star in the 6th century. I don’t know of any movie heroes who went to Deneb. The name means “tail of the Swan,” hardly a romantic destination for space-faring adventurers.

Look toward the Summer Triangle and you are looking down the spiral arm of the Milky Way that we live in. The stars of that arm appear as a packed stellar cloud running through Cygnus the swan, the constellation that contains Deneb.

I took this shot Saturday night, from home, on what turned out to be a very clear night, once some clouds got out of the way in the early evening. This is a 4-image stack of 8-minute exposures, at f/4 with the 35mm Canon lens, a favourite of mine, on the Canon 5D MkII at ISO 800. I added in exposures taken through a soft-focus filter to give the added glows around the stars to help make the bright stars and their colours more visible.

— Alan, September 25, 2011 / Image © 2011 Alan Dyer