circumpolar – The Amazing Sky

August 25, 2016

The Moving Stars of the Northern Hemisphere

I present a montage of time-lapses illustrating the motion of the sky in the Northern Hemisphere.

Any stargazer should be familiar with how the sky moves, with stars rising in the east and setting in the west.

From the northern hemisphere, when we look north we see the sky rotating counter-clockwise around the North Celestial Pole, near Polaris. As you’ll see in the video, even Polaris moves, though not much over the night. The stars that never set, but just move across the northern horizon, are the circumpolar stars.

When we look south we see the seasonal constellations, the ones that rise and set, and change over the seasons.

I shot the images for these sequences from southern Arizona, in early December 2015.

So the night starts with the summer stars setting in the west and the autumn stars dominating the sky. But then Orion and the winter stars rise and march across the sky over the night, setting before dawn, as the spring stars rise.

The south-looking movie is a dusk-to-dawn sequence. Note the Zodiacal Light in the west at right in the early evening, then reappearing in the east at left before dawn brightens the sky, and as Venus and the Moon rises.

Also note the moving bands of red and green airglow, a natural phenomenon of the upper atmosphere.

I posted a matching set of movies in my previous blog post, shot from the Southern Hemisphere. But here’s the link to the movie.

Both sets of movies were shot from nearly identical latitudes – about 31°, but 31° N for Portal, Arizona and 31° S for Coonabarabran, Australia.

As such the Celestial Poles appear at equal altitudes above the horizon. And the angles that the stars rise and set at in relation to the horizon are the same.

But the direction they move is opposite. When looking 180° away from the Pole, the seasonal stars move from left to right in the Northern Hemisphere, but from right to left in the Southern Hemisphere.

Visitors from one hemisphere to the other are bound to get turned around!

September 13, 2015September 13, 2015

The Dancing Lights over Dinosaur Park

The Northern Lights dance over the badlands of Dinosaur Provincial Park, a World Heritage Site.

Aurora alerts called for a fine display on Friday, September 11. Forewarned, I headed to one of my favourite shooting spots at Dinosaur Provincial Park, and aimed three cameras at the sky. It didn’t take long before the lights appeared, right on cue.

The display started out with lots of promise, but did fade after 12:30 a.m., just when it was supposed to be peaking in intensity. I let the cameras run for a while but eventually stopped the shutters and packed it in…

…But not before I captured this odd bit of aurora in the east, shown below, that appeared as an isolated and stationary band pulsing up and down in brightness, but with little movement.

I’ve seen these before and have never heard a good explanation of what process creates such an effect, with a patch of sky appearing to “turn on” and off.

You can see the effect at the end of the time-lapse compilation, linked below from Vimeo.

As usual, please enlarge to full-screen and watch in HD for the best quality.

Unfortunately, a patrolling park official checking on things, spoiled some frames with her truck’s headlights. It’s one of the hazards of time-lapse imaging.

As a final image, here are all the fish-eye lens frames stacked into one image, to create a single star trail showing the sky rotating about the celestial pole.

A composite stack of 198 images creating a circumpolar star trail image of the entire sky, with the motion of the stars and the Northern Lights over an hour recorded onto one frame. The 8mm fish-eye lens take in almost all the sky, with the camera aimed northeast to the centre of the auroral arc, with Polaris, the centre of the sky’s rotation, at left. The scene is at Dinosaur Provincial Park in Alberta, from September 11, 2015. Each exposure was 20 seconds at f/3.5 with the Sigma 8mm lens and at ISO 6400 with the Canon 6D. The ground comes from a stack of 16 images taken early in the sequence turned into a smart object and mean combined with Mean stack mode, to average out and smooth noise. The sky comes from 198 exposures, Lighten stacked using the Advanced Stacker Actions from StarCircleAcademy.com. — Each exposure was 20 seconds at f/3.5 with the Sigma 8mm lens and at ISO 6400 with the Canon 6D. The ground comes from a stack of 16 images taken early in the sequence turned into a smart object and mean combined with Mean stack mode, to average out and smooth noise. The sky comes from 198 exposures, Lighten stacked using the Advanced Stacker Actions from StarCircleAcademy.com.

It’s been a good week for auroras, with a promise of more to come perhaps, as we approach equinox, traditionally a good time for magnetic field lines to align, funnelling solar storm particles into our magnetosphere.

Keep looking up!

June 16, 2015June 16, 2015

Solstice Sky at Dinosaur Park

The stars circle the bright northern sky at solstice time over the Alberta Badlands.

I spent the evening and well into the night on Monday shooting at a favourite spot, Dinosaur Provincial Park in southern Alberta. The result of about an hour of shooting around midnight is the circumpolar star trail composite at top.

It shows the stars spinning about Polaris, while the northern horizon is rimmed with the bright glow of all-night twilight.

Particularly bright in the northwest are noctilucent clouds low on the horizon. These are high-altitude clouds near the edge of space catching the sunlight streaming over the pole at this time of year.

They are a phenomenon unique to the weeks around solstice, and for our latitudes on the Canadian Prairies.

The close-up shot above shows their intricate wave-like formation and pearly colour. They faded though the night as the Sun set for the clouds. But they returned in the pre-dawn light.

If you live at mid-northern latitudes, keep an eye out for these clouds of solstice over the next month. It’s now their peak season.

June 1, 2015June 2, 2015

Night of the Space Station

The Space Station is now continuously lit by sunlight, allowing me to capture dusk-to-dawn passages of the ISS.

On the night of May 31/June 1 I was able to shoot four passages of the International Space Station on successive orbits, at 90-minute intervals, from dusk to dawn.

The first passage, at 11:06 p.m., was low across the south. It’s the image at top.

Then at 12:45 a.m. the Space Station came over again, now directly overhead. It’s the image above. The Moon is the bright glow at bottom.

One orbit later, at 2:21 a.m., the Station came over in another overhead pass in the bright moonlight.

The final passage of the night came at 3:55 a.m. as the sky was brightening with dawn twilight and the Moon was setting. This was another passage across the south, and made for the most photogenic pass of the night.

Here’s an edited movie of the four passes, with a little music just for fun.

Seeing the Space Station on not one but two, three, or even four orbits in one night is possible at my latitude of 50 degrees north around summer solstice because the Station is now continuously lit by sunlight — the Sun never sets from the altitude of the ISS.

When the ISS should be entering night, sunlight streaming over the north pole still lights the Station at its altitude of 400 km.

To shoot the time-lapse clips and stills I used 8mm and 15mm fish-eye lenses, and a 14mm ultra-wide lens.

The bright moonlight made it possible to use short 2- to 4-second exposures, allowing me to record enough frames at each passage to make the little movies of the ISS flying across the sky. Keep in mind, to the eye, the ISS looks like a bright star. Some image processing trickery adds the tapering trails.

I used the Advanced Stacker Actions from StarCircleAcademy.com to create the trail effects, and to stack the time-lapse frames into single composite still images. The gaps in the trails are from the one second interval between frames.

May 11, 2015May 11, 2015

The Red Aurora of May 10

A strange red arc of aurora moved slowly across the sky on May 10.

All indicators looked favourable early in the evening on May 10 for a good auroral display later that night, and sure enough we got one. But it was an unusual display.

From my site in southern Alberta, the northern sky did have a diffuse glow of “normal” green aurora that never did take much form or structure.

But overhead the aurora took the form of an arc across the sky, starting as an isolated ray in the southeast initially, then reaching up to arch across the sky with what looked to the eye like a colourless band.

But the camera showed it as a red arc, with just a fringe of green curtains appearing for a few minutes.

Be sure to click HD and enlarge the video to fill your screen.

The time-lapse movie shows the sequence, over about 90 minutes, with 170 frames playing back at 12 frames per second. You can see the red arc develop, then become more narrow, then exhibit a few green curtains. Then it fades away.

Large-scale pulses also brighten the whole sky momentarily.

The other images are individual frames taken during the evening, showing snapshots of the red arc development, as it became more narrow in structure and gained green curtain-like fringes.

Presumably the red structure was very high in the atmosphere while the green curtains attached to it that did appear hung down from the high-altitude red arc.

I shot all images with an 8mm fish-eye lens to capture most of the sky. The camera is looking north toward Polaris, with the Big Dipper almost directly overhead near the centre of the frames.

The main image at top is a star-trail stack of 80 frames showing the sky’s circumpolar motion around Polaris and the aurora blurred and blended over 45 minutes of motion. I stacked the frames with the Advanced Stacker Actions from StarCircleAcademy.com

April 8, 2015April 8, 2015

Nightscapes at Double Arch

The iconic Double Arch looks great under dark skies, moonlight, or painted with artificial light.

Last night, I returned to the Double Arch at Arches National Park, to capture a star trail series, starting from the onset of darkness at 9:30 p.m., and continuing for 2.5 hours until midnight, an hour after moonrise at 11:00 p.m. The lead image is the result.

I think it turned out rather well.

The Big Dipper is just streaking into frame at top right, as I knew it would from shooting here the night before. The bright streak at upper left is Jupiter turning into frame at the end of the sequence. Note how the shadow of the moonlit foreground arch matches the shape of the background arch.

On the technical end, the star trail composite is a stack of 160 frames, each 45 seconds at f/2.8 and ISO 3200, with the Canon 6D and 14mm lens. The foreground, however, comes from a stack of 8 frames taken toward the end of the shoot, as the moonlight was beginning to light the arches. An additional 45-second exposure taken a couple of minutes after the last star trail frame adds the star-like points at the “head” of the star trail streaks.

I used the excellent Advanced Stacker Actions from StarCircleAcademy to do the stacking in Photoshop.

Before starting the star trail set, I took some initial short-exposure nightscapes while the sky was still dark. The result is the above image, of Double Arch in a dark sky. Passing car headlights provided some rather nice accent illumination.

On such a fine night I thought others might be there as well. Arches is a very popular place for nightscape imaging.

Sure enough, 6 others came and went through the early evening before moonrise. We had a nice time chatting about gear and techniques.

As expected, a few photographers came armed with bright lights for artificially lighting the arches. I kept my camera running, knowing any illumination they shone on the foreground wouldn’t affect my star trails, and that I’d mask in the foreground from frames taken after moonrise.

Here’s one frame from my star trail sequence where one photographer headed under the arch to light it for his photos. It did make for a nice scene – a human figure adds scale and dimension.

However, I always find the light from the LED lamps too artificial and harsh, and comes from the wrong direction to look natural. I also question the ethics of blasting a dark sky site with artificial light.

On a night like this I’d rather wait until moonrise and let nature provide the more uniform, warmer illumination with natural shadows.

As an example, I took this image the night before using short exposures in the moonlight to capture the Big Dipper over Double Arch. When I shot this at 11 p.m. I had the site to myself. Getting nature to provide the right light requires the photographer’s rule of “waiting for the light.”

July 29, 2014

Swirling Stars at a Star Party

The stars of the northern sky swirl in circles around the North Star.

This is admittedly a fanciful effect but an attractive one. The above image records the rotating night sky as it spins around the north celestial pole near Polaris. I stacked 250 image to create this concentric star swirl.

To produce the image I used the excellent Advanced Stacker Actions from StarCircleAcademy, using the new version 14e actions. They include this novel “elastic” effect which produces trails with point-like stars at the beginning and end of the trails.

Another variation, the Short Comets effect, produced this image, with the stars turned into swirling comets.

I took the images for these composites at the Table Mountain Star Party near Oroville, Washington last week under superb skies. The same images that went into these still image stacks can be used to create time-lapse movies.

July 11, 2014

Circling Stars Over the Open Range

The stars swirl in circles above the big sky country of the Canadian Prairies.

For these images I set the camera to take hundreds of images over the course of about 4 hours, then stacked about 100 frames for each of the composites. I stacked the images with the application StarStax.

The result shows the stars circling the North Celestial Pole and Polaris in the northern sky. The top image is from earlier in the night when the Moon was still up lighting the landscape.

The image above is from late in the night, after moonset, and with the glow of dawn beginning to brighten the northern sky. Some low noctilucent clouds are also appearing on the horizon.

This was a beautiful night at Reesor Ranch in Saskatchewan, on the edge of Cypress Hills Interprovincial Park, on the Alberta-Saskatchewan border. I’ve just wrapping up a week of shooting here with clear nights every night but two. The hard drives are full!

August 11, 2013August 11, 2013

Space Station Over a Star Party

The Space Station flies over a campground of astronomers awaiting the fall of darkness.

Last night was the main night for summer star parties, being a dark-of-the-Moon Saturday in August. As I usually am each year, I was in Cypress Hills, Saskatchewan, attending the annual Saskatchewan Summer Star Party. About 330 attended this year, a near record year.

The night was partly cloudy but stayed clear enough for long enough to allow great views. As the sky was getting dark the International Space Station flew over from horizon to horizon, west to east, passing nearly overhead. I had a camera and ultra-wide lens ready and caught the pass in 10 exposures, each 30 seconds long, here stacked in Photoshop. The accumulated exposure time also makes the stars trail in circles around the North Star at upper right.

It was one of many fine sky sights hundreds of stargazers enjoyed this weekend at the SSSP, and no doubt at dozens of other star parties around the continent this weekend.

July 28, 2013

Canola Field Stars

Stars in a blue sky wheel above a ripening field of yellow canola.

It’s been a couple of fine nights of nightscape shooting under the light of the waning Moon and clear skies.

I’ve been shooting from no more exotic location than my local rural neighbourhood, travelling for 5 minutes to spots near one of the many canola fields growing nearby. I wanted to grab some nightscapes over the fields before they lose their yellow flowers and turn green.

The feature image above looking north is from a time-lapse sequence and stacks several images with the “comet trail” effect, to show the northern stars turning about the North Star.

This image, also a frame from another time lapse with a longer lens, shows the Big Dipper above that same field but in an exposure short enough to prevent the stars from trailing. You can now make out the familiar Dipper pattern.

This is a very Canadian scene, with the Big Dipper high in a northern latitude sky, and with the foreground crop a Canadian one – Canola was developed in the 1970s at the University of Manitoba. The “can” in canola stands for Canada. Pity there was no aurora.

July 25, 2013

Star Rain

The sky seems to swirl in a rainstorm of stars.

I’ve combined several exposures of the stars in the northern sky to create a “comet trail” effect, showing them turning about the celestial pole. The top photo looks northwest to the stars around the Big Dipper and picks up the purple light of a faint aurora.

For the photo below, taken on a different night, I used a fish-eye lens to capture the entire sky, but looking north. You can see how the sky turns counterclockwise about the Pole Star. The Milky Way also appears as a blurred band of light.

I shot these last week from the cabin at Reesor Ranch in Saskatchewan during a wonderful week of nightscape photography in the Cypress Hills.

To create these images I used the Advanced Stacking Actions from Star Circle Academy.

September 3, 2012

The Windblown Stars

Here’s the “long” version of an image I posted a few days ago. This combines 430 exposures to make one long star trail image.

A bright meteor appeared in one of the hundreds of 5-second-long exposures and registers in the composite, streaking diagonally across the star trails. The stars circle around Polaris at top. The horizontal streaks are clouds blowing from left to right across the sky during the night. The blades of the windmill in the Wintering Hills wind farm are blurring by the long exposures.

It’s been a productive few nights shooting out at the wind farm, capturing scenes of harvesting the wind!

July 14, 2012

Circling Star Trails in the Rockies

Let the camera shoot for a few hours and this is what you get: stars circling the sky, turning into concentric paths around the North Star.

For this image I stacked 230 short exposures, each 50 seconds long, taken over about 4 hours time on July 7/8. My previous blog entry is one of those individual frames. But in this composite, the stars become trails rotating about the pole of the sky, near Polaris, the North Star, here over Num-Ti-Jah Lodge at Bow Lake in Banff. Moonlight provides the illumination and turns the sky blue, just as in daytime, only much dimmer. But the long exposures bring out the colours and make the scene look like daylight, because the light of the Moon is daylight, just reflected first off the Moon’s neutral grey face.

The same frames used to make this still frame composite can also be used to make a time-lapse movie of the circumpolar stars turning.

July 11, 2012

Big Dipper over Num-Ti-Jah Lodge

“Around the fire tonight Jim Simpson said that for his money this campsite was the closest one could get to heaven on Earth. And I reckon he’s not far wrong.” — Bill Peyto at Bow Lake, July 11, 1902.

Peyto penned that description 110 years ago to the day. His friend always said he’d build a shack here one day. And he did. This is Num-Ti-Jah Lodge, a classic wood log building, hand-hewn and assembled by Jimmy Simpson and his family in the 1940s. They ran the lodge for many years.

I was there this past weekend, July 6 and 7, shooting nightscape photos under the waning Moon. This view looks due north, with the Big Dipper and Polaris over the lodge. To the right, in the northeast, glows a faint red aurora. To the northwest stands Mount Jimmy Simpson, named for the pioneer who built his dream lodge at his heaven-on-Earth campsite.

Heaven is not without its dangers however. Earlier in the evening a yearling grizzly bear was wandering around the lodge and had to be scared off by a Parks official. I’m glad he did! Meeting a bear in the dark is a hazard of shooting in the mountains I have yet to encounter, and don’t wish to.

July 18, 2011July 19, 2011

Circling the Sky

It has been an incredible week for imaging. Clear skies and a bright Moon are the tickets to nightscape photography. And in the last week we’ve had clear moonlit nights in abundance.

I’ve taken advantage of the run of great weather to shoot an old farmstead down the road from my house, on several nights. This is a shot from the first night out, on Thursday, July 14. It is a fish-eye lens shot taking in most of the sky, and looking north at the bottom of the frame. The star trails, taken over 2 hours, circle around the North Star (or close to it).

So why is the sky blue? The Full Moon, just out of the frame at top, is illuminating the landscape and sky — and light from the Full Moon is the same colour as light from the Sun (because that’s what moonlight is! — reflected sunlight). It’s just that moonlight is much dimmer. Expose long enough and you get a scene that looks like daylight but has the stars in it.

To create this image I took 400 18-second exposures, taken 1 second apart, using the Canon 5D MkII camera at ISO 800 and the Sigma 8mm lens at f/5. I stacked the images using an automated “action” for Photoshop developed by astrophotographer Chris Schur. The original frames can also be strung together in sequence to create a time-lapse movie of the sky turning, suitable, in this case, for projection in a full-dome digital planetarium. I’ll post some of those shortly.

But after several nights of shooting till 3 and 4 a.m., and accumulating 100 gigabytes or more of RAW files, it’s time to take a night off and turn in early! At 1 a.m.!