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

Legends of the Fall


These stars are as much a part of autumn in the northern hemisphere as are the changing colours of leaves and the flying south of geese.

These are the stars of legend, outlining the mythical constellations of Queen Cassiopeia (at top left), her daughter Andromeda (arcing across the bottom half of the image), and the hero Perseus (the stars at lower left) who rescued Andromeda from the ravages of Cetus the sea monster.

These stars are now high in the east in the evening sky, heralding the start of autumn and the return of frosty nights.

There are lots to see with binoculars or a telescope in these constellations. Look around this image and you can pick out several clumps, or clusters, of stars in Perseus and Andromeda. But the most obvious object is the oval-shaped Andromeda Galaxy, visible to the unaided eye from dark rural skies. This is the nearest sizeable galaxy to our Milky Way, and yet its light still takes 2.5 million years to reach us.

I took this shot earlier this week during a run of clear and warm autumn nights, perhaps the last before the chill nights of fall come on. It’s a wide-angle shot with a 35mm lens and Canon 5D MkII camera, tracked for a stack of four 6-minute exposures plus a fifth taken with a soft-focus filter.

— Alan, October 1, 2011 / Image © 2011 Alan Dyer