The Colourful Curtains of the Northern Lights


All-Sky Aurora #1 (Feb 17, 2015)

The Northern Lights have performed beautifully the last few nights, presenting curtains of light dancing across the sky.

Two nights ago in Churchill, Manitoba we were treated to a “storm level” show of aurora, with the Lights all across the sky in green curtains waving and curling before our eyes.

The curtains tower several hundred kilometres up into the atmosphere, from the lower edge at about 80 km up (still high above the stratosphere) to the curtain tops at about 400 km altitude at the edge of space.

The camera picks up the colours far better than the eye can, recording not only the predominant green hues but also shades of pink, magenta and red.

All-Sky Aurora #5 (Feb 17, 2015)

The magentas and reds come from the sections of the curtains at the highest altitudes, from the top of the auroral curtains. Here, where the atmosphere is a near vacuum, sparse oxygen atoms can glow with a red emission line.

However, there must be a blue component as well, leading to the magenta or pink tones, as in my photos here. Nitrogen can glow in blues and purples and might be contributing to the colours.

The top two photos are from Tuesday night, Feb 17, when storm levels of 5 were in effect worldwide.

All-Sky Auroral Curtains #2 (Feb 18, 2015)

Lower down, at about 100 km altitude, the air is denser and oxygen glows with a brighter green hue, which the eye can detect more easily.

The photo above from last night, with an activity level of just 2, also shows most of the sky covered with a faint emission, with a patchy appearance, with dark “holes” also moving and flowing in the time-lapse movies I shot.

Closer to the horizon, and far to the north, the aurora brightens into the more characteristic green snaking curtains.

Red Auroral Curtains

This image from three nights ago shows an usually coloured aurora at the start of the night, glowing mostly a deeper red and orange.

The green was still off in the distance far to the east. It arrived a few minutes later as green curtains swept in over us.

But the initial red was from low-energy electrons lighting up just high-altitude oxygen. Only when the higher energy particles arrived did the sky light up green.

All-Sky Aurora #7 (Feb 17, 2015)

I shot all these images with an 8mm fish-eye lens as frames in time-lapse sequences intended for use projected in digital planetarium domes, where the 360° “all-sky” scene would be recreated on the dome as it was in real life.

If you are with a planetarium, contact me if you’d like to get aurora clips.

Our second group of aurora tourists has arrived today at the Churchill Northern Studies Centre, and the weather is warming to a high of -20° C. Balmy!

We’re hoping for more fine displays, though the space weather forecast calls for a quiet magnetic field in the next few days.

– Alan, February 19, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Waves of Northern Lights in Time-Lapse


Aurora - Feb 7, 2014 (Fisheye #3)

Watch waves of aurora wash over the sky rising out of the west to swirl overhead.

This was the spectacle we saw Friday night at the Churchill Northern Studies Centre, as the northern lights filled our sky. I set up my camera on the east side of the main building, out of the bitterly cold west wind. The fish-eye lens is aimed west but its view takes in most of the sky.

The bright object at lower left is the Moon.

The still image above is a frame from the 349-frame time-lapse movie below.

Each frame is a 7-second exposure at f/3.5 and ISO 1250. The interval is 1 second.

The movie covers about 45 minutes of time, compressed into 30 seconds. It shows the aurora peaking in intensity, then fading out behind the ever-present thin cloud drifting through all night.

What amazes me are the waves and loops of auroral curtains that come at us from the west (bottom behind the building) then swirl around the zenith overhead. They move off to the east and north at the top of the frame.

Even watching this in real-time the scene was astonishing. The curtains rippled so quickly, forming and reforming over the sky, you didn’t know where to look. As the image above shows, people just stood amazed.

— Alan, February 9, 2014 / © 2014 Alan Dyer

P.S.: You can view a better-grade version of the movie at my Flickr site.

Aurora Shining Through the Clouds


Churchill Aurora Feb 2-3, 2014

Tonight the aurora shone so brightly for a time it was visible through the cloud.

Here at the Churchill Northern Studies Centre we’ve been battling clouds all week. But on several nights the clouds have cleared for 30 minutes or more, enough to give us glimpses of the aurora and stars. Tonight, February 2/3, the clouds never did clear away enough for a great view. This was as good as it got, with the Northern Lights shining through haze and cloud but nevertheless filling the sky.

Remarkably, this was on a night when the usual indicators of auroral activity were registering all quiet. This shows the benefit of traveling north to stand right under the auroral oval, the zone of maximum activity. In this case I’m at 58° North, in Churchill, Manitoba. Even on a quiet night the Churchill sky can be filled with curtains of dancing colours.

– Alan, February 3, 2014 / © 2014 Alan Dyer

 

Flying Through a Moonlit Winter Night


ISS Pass with Astronaut Chris Hadfield (Feb 15, 2013)

Tonight the Space Station flew out of the west and overhead as it faded into the shadow of the Earth.

Because tonight the ISS was coming up high into the north, almost directly overhead, I used a fish-eye lens to shoot the entire sky, and took three exposures, each 90 seconds with the camera tracking the stars.

The bright Moon is at right, but despite its light the Milky Way still shows up. The Space Station faded into sunset just as it crossed the Milky Way.

Canadian astronaut Chris Hadfield is on board, about to take command at the next crew change. He’s been tweeting lots of comments and photos from space. Check him out at @Cmdr_Hadfield.

– Alan, February 15, 2013 / © 2013 Alan Dyer

 

Horizon to Horizon Milky Way


The view doesn’t get any wider than this. This fish-eye image takes in the entire night sky and summer Milky Way.

I shot this last weekend at the Saskatchewan Summer Star Party in Cypress Hills. Red lights of observers streak along the horizon around the perimeter of the circular image. At centre is the zenith, the point in the sky straight overhead.

The sky was very dark, but the sky close to the horizon is tinted with the faint glows of aurora and airglow.

The Milky Way is the main feature of the summer sky, here stretching from Sagittarius in the south at bottom to Perseus at top in the north. Wide shots like this really put the giant lanes of dust into proper context; you can see their full structure and faint tendrils extending well off the Milky Way band.

For these fish-eye shots (suitable for projection in a planetarium) I used a Sigma 8mm fish-eye lens and a full-frame Canon 5D MkII camera. This is a stack of five 5-minute exposures, all tracked. The landscape is from just one of the images, to minimize blurring of the ground.

— Alan, August 23, 2012 / © 2012 Alan Dyer

Calgary Lights Up


I’m getting the hang of shooting demanding day-to-night time-lapse movies!

For this clip I shot over 2.5 hours, using a fish-eye lens, to create a sequence suitable for projection in a digital planetarium dome.

But the trick with these day-to-night sequences is getting a smooth transition in exposures, which can range over 12 to 16 f-stops, from short snapshot exposures with the lens stopped all the way down at the start before sunset, to long 8-second exposures with the lens wide open at night, plus the camera’s ISO speed increasing from a slow ISO 100 to a faster ISO 400 or more at select points through the sequence as well.

The secret to doing this is a control box called the Little Bramper, an intervalometer that fires the shutter automatically at set intervals but also gradually ramps the exposure time a tad longer with each successive exposure. This was my third time out with the Bramper, and I more or less got it right this time!

While the Bramper does a great job running the camera, it still takes a lot of manual oversight to control its ramping rate so the exposures don’t get too long and overexpose the scene, or fail to get long enough to track the darkening sky.

At several points in the sequence it is also necessary to quickly (in one exposure cycle) half the exposure time, while at the same time opening up the lens a stop, or doubling the ISO, so that the ever-lengthening exposure doesn’t get too long and collide with the interval between exposures. In this case, shots were taken about 12 seconds apart, so the maximum exposure for each frame couldn’t be much more than 8 to 10 seconds.

The end result of the work is a time-lapse movie that shows the setting Sun, then the lights of Calgary coming on as the sky darkens. Clouds lit by the yellow glow of streetlights move in, then blow away again to reveal a few stars in the urban sky.

— Alan, October 16, 2011 / Movie © 2011 Alan Dyer

Space Station Over the Rockies


This was the view Friday night, August 19, 2011, as the International Space Station flew over Banff, Alberta and the Canadian Rockies.

I took this shot (actually this is a composite of three successive exposures) from the viewpoint on Mt. Norquay overlooking the Banff townsite and the Trans-Canada Highway interchange, unfortunately all too well lit. This might well be a case study in light pollution as well.

But the lights in the valley don’t diminish the Milky Way above, and the sky-wide streak created by the passage from west to east of the Space Station. What looks like a brilliant star to the eye turns into a streak here due to the three 45-second time exposures I used to capture this scene. The lens is the 8mm fish-eye, and these frames are from a 400-frame time-lapse movie for the planetarium dome.

— Alan, August 20, 2011 / Image © 2011 Alan Dyer