The Ghostly Glow of Gegenschein


Northern Spring Sky Panorama

It takes a dark spring night to see it well, but now lurking near Jupiter is a ghostly sky glow called Gegenschein. 

This diffuse glow lies directly opposite the Sun. It is caused by sunlight reflecting off interplanetary dust particles in the outer solar system. They reflect light more effectively at the anti-Sun point where each dust particle is fully lit by the Sun.

Like the Sun, the Gegenschein moves around the sky along the ecliptic, moving about a degree from west to east from night to night. March and April provide good nights for seeing the Gegenschein as it then lies in an area of sky far from the Milky Way.

Even so, it is very subtle to the unaided eye. Look south at about 1 a.m. local daylight time.

However, this year, in early April the Gegenschein will be more difficult as it will then lie right on top of Jupiter, as that planet reaches its point opposite the Sun on April 7. Jupiter will then be superimposed on the Gegenschein.

The main image at top is a 7-image vertical panorama of the spring sky, from Corvus and Virgo above the horizon, up past Leo, into Ursa Major and the Big Dipper overhead. Spica lies below bright Jupiter, Arcturus in Böotes is at left, while Regulus in Leo is at right. The grouping of stars near centre is the Coma Berenices star cluster.

Orion over the Old Barn

Earlier in the night, I shot the sky’s other main glow – the Milky Way, as the winter portion of the Milky Way around Orion set into the southwest.

But over in the west, at the right edge of the frame, is the Zodiacal Light, caused by the same dust particles that create the Gegenschein, but that are located in the inner solar system between us and the Sun.

The Zodiacal Light is better depicted in images in my previous post from Dinosaur Park

We bid adieu to the winter Milky Way now. As it departs we are left with an evening sky without the Milky Way visible at all. As seen from northern latitudes it lies along the horizon.

But later in spring, late at night, we’ll see the summer Milky Way rising, beginning its seasons of prominence until late autumn.

— Alan, March 19, 2017 / © 2017 Alan Dyer / AmazingSky.com 

 

A Starry Night in the Badlands


Winter Milky Way Arch and Zodiacal Light

In a winter of cloud, the skies cleared for a magical night in the Alberta Badlands.

Two weeks ago, on February 28, I took advantage of a rare and pristine night to head to one of my favourite spots in Dinosaur Provincial Park, to shoot nightscapes of the winter sky over the Badlands.

A spate of warm weather had melted most of the snow, so the landscape doesn’t look too wintery. But the stars definitely belong to winter in the Northern Hemisphere.

The main image above shows the winter Milky Way arching across the sky from southeast (at left) to northwest (at right). The tower of light in the west is the Zodiacal Light, caused by sunlight reflecting off dust particles in the inner solar system. It is an interplanetary, not atmospheric, effect.

Winter Sky Panorama at Dinosaur Park (Fish-Eye View)
This is a stitch of 6 segments with the 12mm Rokinon lens at f/2.8 for 30 seconds each, with the Nikon D750 at ISO 6400, mounted portrait. Stitched with PTGui.

Above, this 360° version of the scene records the entire sky, with the winter Milky Way from horizon to horizon. With a little averted imagination you can also trace the Zodiacal Light from west (right) over to the eastern sky (left), where it brightens in the diffuse glow of the Gegenschein, where dust opposite the Sun in the outer solar system reflects light back to us.

Winter Sky Panorama at Dinosaur Park (with Labels)
This is a stitch of 6 segments taken with the 12mm full-fame fish-eye Rokinon lens at f/2.8, all 30-second exposures with the Nikon D750 at ISO 6400. The camera was aimed portrait with the segments at 60° spacings. Stitched with PTGui using equirectangular projection with the zeith pulled down slightly.

A rectangular version of the panorama wraps the sky around from east (left), with Leo rising, to northeast (right), with the Big Dipper standing on its handle. I’ve added the labels in Photoshop of course.

Winter Stars over Dinosaur Park
This is a stack of 8 x 30-second exposures for the ground, mean combined to smooth noise, plus one 30-second exposure for the sky. All at f/2.2 with the Sigma 20mm Art lens and Nikon D750 at ISO 6400.

Here, in a single-frame shot, Orion is at centre, Canis Major (with Sirius) is below left, and Taurus (with Aldebaran) is at upper right. The Milky Way runs down to the south. The clusters M35, M41, M46 and M47 are visible as diffuse spots, as is the Orion Nebula, M42, below Orion’s Belt.

Evening Zodiacal Light at Dinosaur Park
The late winter evening Zodiacal Light, from at Dinosaur Provincial Park, Alberta, February 28, 2017. This is a stack of 7 x 30-second exposures for the ground, mean combined for lower noise, plus one 30-second exposure for the sky, all at f/2 with the 20mm Sigma Art lens, and Nikon D750 at ISO 6400.

This is certainly my best shot of the evening Zodiacal Light from my area in Alberta. It is obvious at this time of year on moonless nights, but requires a site with little urban skyglow to the west.

It is best visible in the evening from northern latitudes in late winter and spring.

Here, Venus is just setting above the badlands landscape. The Andromeda Galaxy is at right, the Pleiades at left. The Milky Way runs across the frame at top.

There is a common belief among nightscape photographers that the Milky Way can be seen only in summer. Not so.

What they mean is that the brightest part of the Milky Way, the galactic centre, is best seen in summer. But the Milky Way can be seen in all seasons, with the exception of spring when it is largely absent from the early evening sky, but rises late at night.

— Alan, March 14, 2017 / © 2017 Alan Dyer / AmazingSky.com 

 

Jasper by Starlight


Taurus Rising over Mount Kerkeslin

The annual Dark Sky Festival in Jasper National Park ended with the best finale – dark skies, on a beautiful star-filled night. 

On Saturday night, October 22, I left the final set of science talks in the Big Tent at the heart of the Festival and headed out down the Icefields Parkway for a night of shooting Jasper by starlight.

The lead image is of the winter stars, including the Pleiades, rising above Mt. Kerkeslin at Athabasca Falls.

Pleiades and Taurus over Athabasca Falls
The Pleiades star cluster and the other stars of Taurus rising above Mount Kerkeslin at Athabasca Falls, in Jasper National Park, Alberta, October 22, 2016. The sky is brightening with the rising waning Moon off frame at left. Some cloud adds star glows and hazy patches to the sky. This is a stack of 15 exposures, mean combined to smooth noise, for the ground and one exposure for the sky. All are 25 seconds at f/2 with the Sigma 20mm Art lens and Nikon D750 at ISO 6400.

I shot the image above moments later, from the usual viewpoint overlooking the Falls, reduced to a trickle in late autumn. Illumination is solely by starlight – no artificial and glaring light painting here.

Perseus and Cassiopeia over Mt Kerkeslin
The autumn constellations of Perseus, Cassiopeia and Andromeda over Mount Kerkeslin at the Athabasca River Viewpoint on the Icefields Parkway, in Jasper National Park, Alberta. The Andromeda Galaxy is at upper right. The Pleiades are just clearing the mountain top at lower right. Thin clouds add the natural glows around the stars. Illumination is from starlight. This is a stack of 8 exposures, mean combined to smooth noise, for the ground and one exposure for the sky, all 25 seconds at f/2 with the Sigma 20mm lens and Nikon D750 at ISO 6400.

Earlier in the night, I stopped at the Athabasca River Viewpoint and shot the autumn stars of Cassiopeia, Andromeda, and Perseus above Mt. Kerkeslin. The Pleiades are just appearing above the mountain ridge.

Stars over Athabasca River
The autumn stars of the watery constellations of Capricornus, Aquarius, Piscis Austrinus, and Cetus over the Athabasca River and the peaks of the Continental Divide, from the Athabasca River Viewpoint (the “Goats and Glaciers” viewpoint) on the Icefields Parkway, Jasper National Park, Alberta. Thin cloud provides the natural glows around the stars. This is a stack of 8 exposures for the ground, mean combined to smooth noise, and one exposure for the sky, all 25 seconds at f/2 with the Sigma 20mm Art lens, and Nikon D750 at ISO 6400.

From that viewpoint I shot a scene looking south over the river and with the stars of Capricornus and Aquarius above the Divide.

Milky Way over Athabasca Pass
The Milky Way over the region of Athabasca Pass, as seen from the highway viewpoint on the Icefields Parkway, in Jasper National Park, Alberta, Oct 22, 2016. The Milky Way here is the section through Aquila, with Altair at top and Mars bright above the peaks of the Continental Divide. This is a stack of 8 exposures, mean combined to smooth noise, for the ground and one exposure for the sky, all 25 seconds at f/2 with the Sigma 20mm lens, and Nkion D750 at ISO 6400.

At the start of the night I stopped at the viewpoint for Athabasca Pass far in the distance. The summer Milky Way was setting over the pass. This historic pass was used by David Thompson in the late 1700s and early 1800s as his route into B.C. to extend the fur trade across the Divide. Thompson writes in his Journal about one particularly clear night on the pass:

“My men were not at their ease, yet when night came they admired the brilliancy of the Stars, and as one of them said, he thought he could almost touch them with his hand.”

The night ended with a display of Northern Lights over the Athabasca River. What a superb night under the stars in Jasper!

Aurora over Athabasca River
The Northern Lights over the Athabasca River in Jasper National Park, Alberta, Canada, on October 22/23 at about 1:30 am. I shot this from an access point to the Athabasca River by the bridge on Highway 93 on the Icefields Parkway. Pyramid Mountain is at left near the town of Jasper. Vega is the bright star at left; the Big Dipper is at right. The image is a stack of 10 exposures for the ground, mean combined to smooth noise and to smooth the water, and one exposure for the sky and aurora. All 15 seconds at ISO 1600 at f2 with the Sigma 20mm lens and Nikon D750.

As a finale, here’s a music video collecting together still images and time-lapse movies shot this night, and on two other nights during the Dark Sky Festival, including at the big Lake Annette “Beyond the Stars” star party I spoke at.

Enjoy!

As usual, enlarge to full screen and go to HD for the best view.

Thanks!

— Alan, October 24, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

A Night at Police Outpost


Milky Way in Twilight at Police Outpost Park

It was a perfect night at a dark site in southern Alberta. The Milky Way shone to the south and aurora danced to the north.

I had scouted out this location in June and marked it on my calendar to return in the fall when the centre of the Milky Way would be well-placed to the southwest.

The site is Police Outpost Provincial Park, named for the North West Mounted Police fort that once occupied the site, guarding Canada’s sovereignty in the late 1800s.

One result from the night of shooting is the opening image, the first frame from a time-lapse taken while deep blue twilight still coloured the sky. The main peak is Chief Mountain in Montana.

Twilight Aurora at Police Outpost
A fairly mild dispay of aurora in the darkening deep blue twilight over the lake at Police Outpost Provincial Park, in southern Alberta, on September 26, 2016, with the stars of Perseus rising, and with Capella low in the northeast at centre. This is a stack of 4 x 20 second exposures for the dark ground and water to smooth noise and one 20-second exposure for the sky, all with the 25mm Canon lens at f/2.8 and Canon 6D at ISO 2000. 

To the north an aurora display kicked up over the lake. While it never got very bright, it still provided a photogenic show over the still waters.

Aurora over Police Outpost Lake
A fairly mild dispay of aurora over the lake at Police Outpost Provincial Park, in southern Alberta, on September 26, 2016, with the stars of Auriga and Taurus rising, including the Pleiades at upper right. The Hyades in Taurus are the most prominent stellar reflections at lower right, in the still water this evening. Capella is the bright star above centre; Aldebaran is at right. This is a stack of 4 x 20 second exposures for the dark ground to smooth noise and one 20-second exposure for the sky and water, all with the 25mm Canon lens at f/2.2 and Canon 6D at ISO 3200. 

The waters were calm on this windless night (rare for southern Alberta), and so reflected the stars and Northern Lights beautifully.

Big Dipper Reflection
The Big Dipper reflected in the still waters of the lake at Police Outpost Provincial Park, in southern Alberta, on September 26, 2016, with an aurora to the north at right. Only in autumn can one shoot the Dipper reflected in the water in the evening sky, as it is then riding low along the northern horizon. This is from a latitude of 49° N where the Dipper is circumpolar. This is a stack of 4 x 25 second exposures for the dark ground to smooth noise and one 25-second exposure for the sky and water, all with the 25mm Canon lens at f/2.2 and Canon 6D at ISO 3200. 

Here, the Big Dipper reflects in the lake as we look north to the Lights. The movie below compiles still images and two time-lapse sequences, of the Lights and Milky Way. The sounds are the natural sounds I recorded on site, as flocks of geese were getting ready to migrate and the owls hooted.

Enjoy! — As always, for the best view, enlarge to full screen or click through to Vimeo with the V button.

— Alan, October 6, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

A Night at Moraine Lake


Aurora over Desolation Valley PanoramaWhat a night this was – perfect skies over an iconic location in the Rockies. And an aurora to top it off!

On August 31 I took advantage of a rare clear night in the forecast and headed to Banff and Moraine Lake for a night of shooting. The goal was to shoot a time-lapse and stills of the Milky Way over the lake.

The handy planning app, The Photographer’s Ephemeris, showed me (as below) that the Milky Way and galactic centre (the large circles) would be ideally placed over the end of the lake as astronomical twilight ended at 10:30 p.m. I began the shoot at 10 p.m. as the sky still had some twilight blue in it.

Moraine Lake TPE

I planned to shoot 600 frames for a time-lapse. From those I would extract select frames to create a still image. The result is below.

Milky Way over Moraine Lake
This is looking southwest with the images taken about 11:15 pm on August 31, 2016.The ground is illuminated by a mix of starlight, lights from the Moraine Lake Lodge, and from a display of aurora brightening behind the camera to the north. The starclouds of Scutum and Sagittarius are just above the peaks of the Valley of Ten Peaks. This is a stack of 16 images for the ground, mean combined to smooth noise, and one exposure for the sky, untracked, all 15 seconds at f/2 with the Sigma 20mm Art lens and Nikon D750 at ISO 6400. The frames are part of a 450-frame time-lapse.

As the caption explains, the still is a composite of one exposure for the sky and 16 in succession for the ground, averaged together in a technique to smooth noise. The camera wasn’t tracking the sky, so stacking sky images isn’t feasible, as much as I might like to have the lower noise there, too. (There are programs that attempt to align and stack the moving sky but I’ve never found they work well.)

About midnight, the Valley of Ten Peaks around the lake began to light up. An aurora was getting active in the opposite direction, to the north. With 450 frames shot, I stopped the Milky Way time-lapse and turned the camera the other way. (I was lazy and hadn’t hefted a second camera and tripod up the steep hill to the viewpoint.)

The lead-image panorama is the first result, showing the sweeping arc of Northern Lights over Desolation Valley.

Aurora over Desolation Valley #2
The Northern Lights in a fine Level 4 to 5 display over Desolation Valley at Moraine Lake, Banff National Park, on the night of August 31/Sept 1. This is one frame from a 450-frame time-lapse with the aurora at its best. This is a 2-second exposure at f/2 with the Sigma 20mm Art lens and Nikon D750 at ISO 5000.

Still images shot, I began a time-lapse of the Lights, grabbing another 450 frames, this time using just 2-second exposures at f/1.6 for a rapid cadence time-lapse to help freeze the motion of the curtains.

The final movies and stills are in a music video here:

 

I ended the night with a parting shot of the Pleiades and the winter stars rising behind the Tower of Babel formation. I last photographed that scene with those same stars in the 1980s using 6×7 film.

Aurora and Winter Stars Rising over Tower of Babel
The early winter stars rising behind the Tower of Babel formation at Moraine Lake, Banff National Park, with a bright aurora to the north at left. Visible are the Pleiades at centre, and Capella and the stars of Auriga at left. Just above the mountain are the Hyades and Taurus rising. At top are the stars of Perseus. Aries is just above the peak of Babel. The aurora in part lights the landscape green. This is a stack of 16 images for the ground, mean combined to smooth noise, and 1 image for the sky, untracked, all for 15 seconds at f/2.2 with the Sigma 20mm Art lens, and Nikon D750 at ISO 3200. All with LENR turned on.

In a summer of clouds and storms, this was a night to make up for it.

— Alan, September 4, 2016 / © 2016 Alan Dyer / www.amazingsky.com

Member of The World at Night photo group

TWAN-black

 

The Cadence of the Moving Sky


Saturn, Mars and the Milky Way over the Bow River

Saturn, Mars and the Milky Way appeared in the twilight over the Bow River.

I shot this scene on August 24 from the viewpoint at Blackfoot Crossing Historical Park, overlooking the Bow River. Mars appears between Saturn above and Antares below, in a line of objects west of the Milky Way.

The valley below is the traditional meeting place of the Blackfoot Nation, and the site of the signing of Treaty Seven between Chief Crowfoot and Colonel MacLeod of the North West Mounted Police in 1877.

The image is a panorama of two images, each 20-second exposures at f/2 and ISO 1600 with the 24mm lens. I shot them just prior to shooting time-lapses of the moving sky, using two cameras to create a comparison pair of videos, to illustrate the choices in setting the cadence when shooting time-lapses.

The movies, embedded here, will be in the next edition of my Nightscapes and Time-Lapse ebook, with the current version linked to below. The text explains what the videos are showing.

 

Choose Your Style

When shooting frames destined for a time-lapse movie we have a choice:

  • Shoot fewer but longer exposures at slower ISOs and/or smaller apertures.

OR …

  • Shoot lots of short exposures at high ISOs and/or wide apertures.

 

The former yields greater depth of field; the latter produces more noise. But with time-lapses, the variations also affect the mood of a movie in playback.

This comparison shows a pair of movies, both rendered at 30 frames per second:

Clip #1 was taken over 2 hours using 20-second exposures, all at ISO 2000 and f/2 with 1-second intervals. The result was 300 frames.

Clip #2 was taken over 1 hour using 5-second exposures also at f/2 and 1-second intervals, but at ISO 8000. The result was 600 frames: twice as many frames in half the time.

Clip #1 shows fast sky motion. Clip #2 shows slow motion.

Clip #2 exhibits enough noise that I couldn’t bring out the dark foreground as well as in Clip #1. Clip 2 exhibits a slower, more graceful motion. And it better “time-resolves” fast-moving content such as cars and aircraft.

Which is better? It depends …

Long = Fast

The movie taken at a longer, slower cadence (using longer exposures) and requiring 2 hours to capture 300 frames resulted in fast, dramatic sky motion when played back. Two hours of sky motion are being compressed into 10 seconds of playback at 30 frames per second. You might like that if you want a dramatic, high-energy feel.

Short = Slow

By comparison, the movie that packed 600 frames into just an hour of shooting (by using short exposures taken at fast apertures or fast ISOs) produced a movie where the sky moves very slowly during its 10 seconds of playback, also at 30 frames per second. You might like that if you want a slow, peaceful mood to your movies.

So, if you want your movie to have a slow, quiet feel, shoot lots of short exposures. But, if you want your movie to have a fast, high-energy feel, shoot long exposures.

As an aside – all purchasers of the current edition of my ebook will get the updated version free of charge via the iBooks Store once it is published later this year. 

— Alan, August 26, 2016 / © 2016 Alan Dyer / AmazingSky.com

 

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