Nebulas, Clusters and Starfields, Oh My!


Centre of the Galaxy Mosaic

There’s no more spectacular region of the sky than the Milky Way toward the centre of the Galaxy.

What a perfect night it was last night. After moonset between 2 and 3:30 a.m. I shot a series of images around the centre of the Galaxy area and stitched them into a big mosaic of the Milky Way.

The scene takes in the Milky Way from the Eagle and Swan nebulas at top left, down to the Messier 6 and 7 open clusters in Scorpius at bottom. Standing out is the large pink Lagoon Nebula left of centre and the huge region of dark dusty nebulosity popularly called the Dark Horse at right of centre. It’s made of smaller dark nebulas such as the Pipe Nebula and tiny Snake Nebula.

At upper left is the bright Small Sagittarius Starcloud, aka Messier 24, flanked by the open clusters M23 and M25. There are a dozen or more Messier objects in this region of sky.

The actual centre of the Milky Way is obscured by dark dust but lies in the direction just below the centre of the frame, amid one of the bright star clouds that mark this amazing region of sky.

I shot the images for this mosaic from a site near Portal, Arizona, using a 135mm telephoto lens and filter-modified Canon 5D Mark II riding on an iOptron SkyTracker to follow the stars. The mosaic is made of 6 panels, each a stack of five 3-minute exposures. They were all stacked and stitched in Photoshop CC. The full version is 8000 by 9000 pixels and is packed with detail.

I think the result is one of the best astrophotos I’ve taken! It sure helps to have Arizona skies!

– Alan, May 5, 2014 / © 2014 Alan Dyer

 

 

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.

— Alan, June 7, 2011 / Image © 2011 Alan Dyer