The Wonder-Filled Winter Sky

The sky of December contains an amazing array of bright stars and deep-sky delights.

At this time of year we peer out toward the edge of our Galaxy, in the direction opposite to what we see in July and August. Even though we are looking away from the centre of our Galaxy, the Milky Way at this time of year contains a stunning collection of sights – for the naked eye, binoculars or a telescope.

I can’t list them all here, but most are in the lead image above! The image is a mosaic of the northern winter Milky Way, including the brilliant stars and constellations in and around Orion the Hunter.

The Milky Way extends from Perseus in the north at top, to Canis Major in the south at bottom. Throughout the scene are dark lanes and dust clouds, such as the Taurus Dark Clouds at upper right.

The Milky Way is dotted with numerous red “hydrogen-alpha” regions of emission nebulosity, such as the bright Rosette Nebula at lower left and the California Nebula at upper right. The curving arc of Barnard’s Loop surrounds the east side of Orion. Orion is below centre, with Sirius, the night sky’s brightest star, at lower left.

The constellation of Taurus is at upper right and Gemini at upper left. Auriga is at top and Perseus at upper right.

There’s an unusually bright area in Taurus just right of centre in the mosaic which I thought might be an image processing artifact. No. It’s the Gegenschein – a glow of sunlight reflected off comet dust directly opposite the Sun.

Two highlights of this sky that are great regions for binoculars are the Hyades cluster in Taurus ….

…and the Belt and Sword of Orion.

The Hyades – the face of Taurus – is one of the nearest and therefore largest open star clusters.

Orion the Hunter, who battles Taurus in the sky, contains the famous Orion Nebula, here overexposed in order to bring out the much fainter nebulosity in the region.

The magenta and blue arcs in the image below are photographic targets, but the bright Orion Nebula in Orion’s Sword is easy in binoculars, shining below the trio of his Belt Stars.

For us in the northern hemisphere, Orion and company are winter sights. But for those down under, in the southern hemisphere, this is the summer sky. So pardon the northern chauvinism in the title!

Either way, on a dark, moonless night, get out and explore the sky around Orion.

TECHNICAL:

I shot the segments for the main mosaic at top on a very clear night on December 5, 2015 from the Quailway Cottage at Portal, Arizona. This is a mosaic of 8 segments, in two columns of 4 rows, with generous overlap. Each segment was made of 4 x 2.5-minute exposures stacked with mean combine stack mode to reduce noise, plus 2 x 2.5-minute exposures taken through the Kenko Softon filter layered in with Lighten belnd mode to add the star glows. Each segment was shot at f/2.8 with the original 35mm Canon L-series lens and the filter-modified (by Hutech) Canon 5D MkII at ISO 1600, riding on the iOptron Sky-Tracker. All stacking and stitching in Photoshop CC 2015. The soft diffusion filter helps bring out the star colors in this area of sky rich in brilliant giant stars.

— Alan, December 11, 2015 / © 2015 Alan Dyer / www.amazingsky.com