The Summer Triangle Stars

Summer Triangle in the Milky Way

The trio of Summer Triangle stars flank the Milky Way in the dying days of summer.

I shot the featured image above two nights ago on a perfect late summer night from home. Skies were dark and transparent, with no aurora and little airglow to taint the sky.

The image takes in the Summer Triangle stars of Vega (top), Deneb (left) and Altair (bottom). Vega and Altair straddle the summer Milky Way, but Deneb lies right in the thick of it, way down the Local Arm that we live in. Vega and Altair are nearby normal stars, only 25 and 16 light years away. But Deneb is a blue supergiant, shining from 1400 light years away, and one of the most luminous stars in the catalog.

The Milky Way through this area of sky is riven by twisting lanes of interstellar dust. A particularly dark patch sits above Deneb at top left. Then below Deneb the Milky Way gets split by the Great Rift that continues down into Aquila and Ophiuchus at lower right.

All along this part of the Milky Way, particularly around Deneb, the camera picks up a string of glowing red nebulas where stars are forming. The red comes from hydrogen atoms emitting deep red light, as hydrogen is wont to do.

Summer Milky Way from Backyard (Sept 9, 2013)

This image is from a couple of nights earlier. I used a wider angle lens to take in the full sweep of the summer Milky Way, from Sagittarius skimming the horizon, to Cassiopeia past the zenith at the top. You can see the Summer Triangle in the top half of the image, the part of the sky now overhead on early September nights from the northern hemisphere.

I took both shots with a filter-modified Canon 5D MkII placed on a little iOptron SkyTracker for tracked long exposures (4 to 5 minutes). The main image was with a 24mm Canon lens, the bottom image with a 14mm Rokinon lens.

– Alan, September 12, 2013 / © 2013 Alan Dyer


Last of the Summer Milky Way

Milky Way over Mountains at Waterton Lakes (Aug 31, 2013)

The summer Milky Way sets behind the peaks of Waterton Lakes National Park, signalling an end to summer.

This was the scene last Saturday night, on a perfect summer night in the Rockies. The glorious starfields of the summer Milky Way are setting behind the mountains.

The Small Sagittarius Starcloud is just above the mountain ridge while above it are the red patches of the Swan and Eagle Nebulas.

Farther up the Milky Way, stars brighten into another starcloud, the Scutum cloud, flanked by two dark lanes of dust. Above it shine the stars of Aquila, Ophiuchus, Lyra, and southern Cygnus. The two bright stars are Altair (below) and Vega (top right).

Summer Milky Way over Mountains (Aug 31, 2013)

This is an alternative view of the same scene, with the camera in “landscape” orientation.

I took both from a pull-off on the Red Rock Canyon road in Waterton. Each image is a stack of four 3-minute exposures, each tracking the stars with the camera on an iOptron SkyTracker.

The Milky Way from Canada just doesn’t get any clearer or the skies any darker.

– Alan, September 3, 2013 / © 2013 Alan Dyer


The Natural Naked-Eye Milky Way

Centre of the Milky Way Panorama (2011)

In this image I’ve tried to render the Milky Way in a view that simulates what you see with your unaided eyes.

The result is a celestial portrait in subtle shades of black and white.

This is a photo mosaic, but processed contrary to the usual methods – eliminating colour rather than enhancing it, and reducing contrast rather than boosting it. The result is a view that I think quite nicely matches what your eyes see, though certainly from a dark site. And in this case, you would need to be in the southern hemisphere to see this sweep of the Milky Way, from Aquila at left, to the Southern Cross at right, with the bright star clouds around the centre of the Galaxy in Sagittarius and Scorpius in the middle.

I’ve removed colours except for the muted colours of stars. And I’ve tried to render the stars with an intensity and dynamic range that the eye sees but that is often lost in long exposures.

The dark lanes of dust seen here really do look like this under dark skies. The nearby Coal Sack next to the Southern Cross does look a little darker than the rest of the sky. This view also captures another effect you can see in the real sky – the brighter sky below the Milky Way plane beneath Sagittarius and Aquila – there are more stars there, which make the background sky brighter than above the Milky Way plane (along the top of the photo) where the sky is permeated by dark obscuring dust.

This scene also frames the “dark Emu” – the shape drawn in the dark lanes that looks like a flightless emu in the sky. It’s an important “constellation” in Aboriginal mythology in Australia. The emu’s head is the Coal Sack at far right, her neck the long dark lane curving up through Centaurus and Lupus, and her tail the dark lanes at left in Ophiuchus, Scutum and Aquila.

I shot the original images for this panoramic mosaic in Chile in May 2011. You can see the full colour version in my “Milky Way Mosaic” post from 2011. The colours are wonderful. But there’s something enthralling about “capturing” the view more as your eyes – and mind – remember it.

– Alan, February 3, 2013 / © 2013 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