The Moving Stars of the Northern Hemisphere


Arizona Star Trails - Circumpolar Looking North

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!

— Alan, August 25, 2016 / © 2016 Alan Dyer / AmazingSky.com

 

The Dancing Lights over Dinosaur Park


The Northern Lights over the badlands of Dinosaur Provincial Park, Alberta, on September 11, 2015. This is one frame from a 280-frame time-lapse sequence. Although, in this image the ground came from a later exposure in the sequence when passing car headlights lit the ground briefly on an otherwise dark, moonless night, to help sculpt the ground. This was with the Nikon D750 and 24mm lens for 15 seconds at f/2.8 and ISO 6400.

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.

An aurora and the autymn Milky Way over the Badlands of Dinosaur Provincial Park, Alberta, on September 11, 2015. The stars, constellations and Milky Way of the autumn and early winter sky are rising in the northeast, including the objects: the Andromeda Galaxy at top, and the Pleiades at bottom.  This is one frame from a 200-frame time-lapse sequence, though in this image the ground comes from a Mean Combine stack of 7 images to smooth noise but the sky is from one image, each 30 seconds at f/2.8 with the Rokinon 14mm lens and Canon 5D MkII at ISO 3200 on a dark moonless night.

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.

An odd isolated arc of aurora in the eastern sky over the badlands of Dinosaur Provincial Park, Alberta, on September 11, 2015. This arc sat stationary and pulsed up and down in brightness over a few seconds. It was in some frames but not others. The winter stars of Taurus, including the Pleiades cluster, and Auriga are rising in the east.  The sky here is from a single exposure but the ground came from a Mean Combine stack of 8 exposures to smooth noise. Each was 40 seconds at f/2.8 with the 14mm Rokinon lens and Canon 5D MkII at ISO 3200 on a moonless night.

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!

— Alan, September 13, 2015 / © 2015 Alan Dyer / www.amazingsky.com 

Solstice Sky at Dinosaur Park


Summer solstice twilight and circumpolar star trails over the badlands of Dinosaur Provincial Park, Alberta. Some bright noctilucent clouds are visible low on the northern horizon. I shot this June 15, 2015 as part of a shoot for a “star trail” video tutorial, as an example image. This is a stack of the first 200 frames of 275 shot for a time-lapse, each 15 seconds at f/2.8 with the Rokinon 14mm lens and Canon 6D at ISO 1600. I stacked them in Advanced Stacker Actions with the ultrastreak mode. The foreground comes from a mean blend of the first 8 frames, to smooth noise, and to provide a brighter foreground from early in the sequence when the sky and ground were brighter.

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.

Noctilucent clouds (NLCs) over the silhouette of the badlands of Dinosaur Provincial Park in southern Alberta, on the night of June 15/16, 2015. The clouds remained low on the northern horizon and faded as the Sun angle dropped through the night but then reappeared in the northwest prior to dawn. The bright star at left is Capella, circumpolar at this latitude of 50° N.  This is a single exposure for 10 seconds at f/3.2 with the 16-35mm lens and at ISO 800 with the Canon 60Da.

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.

– Alan, June 16, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Night of the Space Station


A pass of the International Space Station in the bright moonlight, on the evening of May 31, 2015, with the gibbous Moon to the south at centre. The view is looking south, with the ISS travelling from right (west) to left (east) over several minutes. This was the first pass of a 4-pass night, May 31/June 1, starting at 11:06 pm MDT this evening. Numerous other fainter satellite trails are also visible. This is a composite stack of 95 exposures, each 2 seconds at f/2.8 with the 14mm lens and ISO 6400 with the Canon 6D. The gaps are from the 1-second interval between exposures. The length of the trails and gaps reflects the changing apparent speed of the ISS as it approaches, passes closest, then flies away.  I stacked the exposures with the Advanced Stacker Actions from StarCIrcleAcademy.com, using the Lighten mode. The ground comes from a Mean blend of just 8 of the exposures to prevent shadows from blurring but to smooth noise.

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.

An overhead pass of the International Space Station in a bright moonlit sky on the night of May 31/ June 1, 2015, with the gibbous Moon in to the south, below. The view is looking south, with the ISS travelling from right (west) to left (east) over several minutes. This was the second pass of a 4-pass night, May 31/June 1, starting at 12:44 am MDT this morning.  This is a composite stack of 91 exposures, each 4 seconds at f/3.5 with the 8mm fish-eye lens and ISO 6400 with the Canon 6D. The gaps are from the 1-second interval between exposures. The length of the trails and gaps reflects the changing apparent speed of the ISS as it approaches, passes closest, then flies away. The stars are trailing around Polaris at top. An aircraft supplies the other dashed trail across the top and intersecting with the ISS trail. I stacked the exposures with the Advanced Stacker Actions from StarCIrcleAcademy.com, using the Lighten mode. The ground comes from a Mean blend of just 8 of the exposures to prevent shadows from blurring but to smooth noise.

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.

An overhead pass of the International Space Station in a bright moonlit sky on the night of May 31/ June 1, 2015, with the gibbous Moon in the southwest, below. The view is looking south, with the ISS travelling from right (west) to left (east) over several minutes. This was the third pass of a 4-pass night, May 31/June 1, starting at 2:21 am MDT this morning.  This is a composite stack of 66 exposures, each 4 seconds at f/3.5 with the 8mm fish-eye lens and ISO 6400 with the Canon 6D. The gaps are from the 1-second interval between exposures. The length of the trails and gaps reflects the changing apparent speed of the ISS as it approaches, passes closest, then flies away. The stars are trailing around Polaris at top. Unfortunately, I missed catching the start of this pass. I stacked the exposures with the Advanced Stacker Actions from StarCIrcleAcademy.com, using the Lighten mode. The ground comes from a Mean blend of just 8 of the exposures to prevent shadows from blurring but to smooth noise.

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

A pass of the International Space Station in the brightening twilight of dawn, on the morning of June 1, 2015, with the gibbous Moon setting to the southwest at right. The view is looking south, with the ISS travelling from right (west) to left (southeast) over several minutes. This was the last pass of a 4-pass night, May 31/June 1, starting at 3:55 am MDT this morning.  This is a composite stack of 144 exposures, each 2 seconds at f/2.8 with the 15mm full-frame fish-eye and ISO 3200 with the Canon 6D. The gaps are from the 1-second interval between exposures. The length of the trails and gaps reflects the changing apparent speed of the ISS as it approaches, passes closest, then flies away.  I stacked the exposures with the Advanced Stacker Actions from StarCIrcleAcademy.com, using the Lighten mode. The ground comes from a Mean blend of just 8 of the exposures to prevent shadows from blurring but to smooth noise.

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.

– Alan, June 2, 2015 / © 2015 Alan Dyer / www.amazingsky.com

The Red Aurora of May 10


A strange red/magenta auroral arc overhead across the sky, with a more normal green diffuse glow to the north, as seen on May 10, 2015, in a stack of 80 frames taken over 45 minutes. The Big Dipper is overhead in the centre of the frame, Jupiter is at left in the west and Arcturus is at top to the south. I shot this from home, using an 8mm fish-eye lens to take in most of the sky, with the camera looking north. The 80 exposures were stacked and blended with Advanced Stacker Actions from StarCircleAcademy.com using the Long Trails effect. Each exposure was 32 seconds at f/3.6 and ISO 3200 with the Canon 6D. An individual exposure adds the more point-like stars at the start of the tapered star trails, and add the blue from the last twilight glow still illuminating the sky at the start of the sequence.

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.

A strange red/magenta auroral arc overhead across the sky, with a more normal green diffuse glow to the north, as seen on May 10, 2015. The Big Dipper is overhead in the centre of the frame, Jupiter is at left in the west and Arcturus is at top to the south. I shot this from home, using an 8mm fish-eye lens to take in most of the sky, with the camera looking north. It is part of a 170-frame time-lapse sequence. Exposure was 32 seconds at f/3.6 and ISO 3200 with the Canon 6D.

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.

A strange red/magenta auroral arc overhead across the sky, with a more normal green diffuse glow to the north, as seen on May 10, 2015. The Big Dipper is overhead in the centre of the frame, Jupiter is at left in the west and Arcturus is at top to the south. I shot this from home, using an 8mm fish-eye lens to take in most of the sky, with the camera looking north. It is part of a 170-frame time-lapse sequence. Exposure was 32 seconds at f/3.6 and ISO 3200 with the Canon 6D.

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

– Alan, May 11, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Nightscapes at Double Arch


Star Trails Behind 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.

Dark Sky Behind Double Arch

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.

Photographer Lighting Double Arch

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.

Big Dipper over Double Arch

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.”

– Alan, April 7, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Swirling Stars at a Star Party


Table Mountain Star Trails-Circumpolar Elastic Effect

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.

Table Mountain Star Party Star Trails #1

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.

– Alan, July 29, 2014 / © 2014 Alan Dyer