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

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.

— Alan, June 26, 2011 / Image © 2011 Alan Dyer

 

 

 

 

 

Southern Spectacular


Everyone from the north who sees this area of sky for the first time quickly realizes just how much better the sky is down south. This is the most spectacular region of the deep-south Milky Way, as it passes through the constellations of Carina, Crux and Centaurus.

Dead centre here is the symbol of the southern sky, the Southern Cross. To the right of it glow the reddish nebulas of Carina and Centaurus; to the left of the Cross lie the dark clouds of the Coal Sack and the pair of brilliant stars, Alpha (on the left) and Beta Centauri. Alpha is the closest bright star to our solar system.

This one field contains much of what makes the southern sky so memorable and a mecca for any backyard astronomer. You haven’t lived an astronomical life until you’ve seen this part of the Milky Way, accessible only from southern latitudes.

I took this shot last night, May 4, 2011, using a Sigma 50mm lens and a modified Canon 5D MkII camera. The image is a stack of four 6-minute exposures at f/4 and ISO 800, plus a stack of two more 6-minute exposures taken through a soft-focus filter, with those images layered into the final Photoshop image to add the star glows and make the constellation outlines, like the Southern Cross, pop out.

– Alan, May 5, 2011 / Image © 2011 Alan Dyer