Conjunctions, Satellites & Auroras, Oh My!


Friday the 13th Aurora Title

October has brought clear skies and some fine celestial sights. Here’s a potpourri of what was up from home. 

We’ve enjoyed some lovely early autumn weather here in southern Alberta, providing great opportunities to see and shoot a series of astronomical events.


Conjunctions

Venus & Mars in Close Conjunction #2 (Oct 5, 2017)
Venus and Mars in close conjunction in the dawn sky on October 5, 2017. Venus is the brightest object; Mars is below it; while the star above Venus is 4th magnitude Sigma Leonis. The foreground is illuminated by light from the setting Full Moon in the west. This is a single 1-second exposure with the 135mm lens at f/2 and Canon 60Da at ISO 800. 

On October 5, Venus and Mars appeared a fraction of a degree apart in the dawn twilight. Venus is the brightest object, just above dimmer but red Mars. This was one of the closest planet conjunctions of 2017. Mars will appear much brighter in July and August 2018 when it makes its closest approach to Earth since 2003.


Satellites: The Space Station

Overhead Pass of the Space Station in Moonlight
An overhead pass of the ISS on October 5, 2017, with the Full Moon rising in the east at left. The ISS is moving from west (at right) to east (at left), passing nearly overhead at the zenith at centre. North is at the top, south at bottom in this fish-eye lens image with an 8mm Sigma fish-eye lens on the Canon 6D MkII camera. This is a stack of 56 exposures, each 4 seconds long at an interval of 1 second. 

The Space Station made a series of ideal evening passes in early October, flying right overhead from my site at latitude 51° N. I captured it in a series of stacked still images, so it appears as a dashed line across the sky. In reality it looks like a very bright star, outshining any other natural star. Here, it appears to fly toward the rising Moon.


Satellites: Iridiums

Twin Iridium Satellite Flares (October 9, 2017)
A pair of nearly simultaneous and parallel Iridium satellite flares, on October 9, 2017, as they descended into the north. The left or westerly flare was much brighter and with a sharp rise and fall in brightness. While it was predicted to be mag. -4.4 I think it got much brighter, perhaps mag -7, but very briefly. These are Iridium 90 (left) and Iridium 50 (right). This is a stack of 40+ exposures each, 2 seconds at 1-second intervals, with the Sigma 24mm lens at f/1.4 and Nikon D750 at ISO 6400.

Often appearing brighter than even the ISS, Iridium satellite flares can blaze brighter than even Venus at its best. One did so here, above, in another time-lapse of a pair of Iridium satellites that traveled in parallel and flared at almost the same time. But the orientation of the reflective antennas that create these flares must have been better on the left Iridium as it really shot up in brilliance for a few seconds.


Auroras

Aurora and Circumpolar Star Trails (Oct, 13, 2017)
A circumpolar star trail composite with Northern Lights, on October 13, 2017, shot from home in southern Alberta. The Big Dipper is at bottom centre; Polaris is at top centre at the axis of the rotation. The bottom edge of the curtains are rimmed with a pink fringe from nitrogen. This is a stack of 200 frames taken mostly when the aurora was a quiescent arc across the north before the substorm hit. An additional single exposure is layered in taken about 1 minute after the main star trail set to add the final end point stars after a gap in the trails. Stacking was with the Advanced Stacker Plus actions using the Ultrastreaks mode to add the direction of motion from the tapering trails. Each frame is 3 seconds at f/2 and ISO 6400 wth the Sigma 14mm lens and Nikon D750.

Little in the sky beats a fine aurora display and we’ve had several of late, despite the Sun being spotless and nearing a low ebb in its activity. The above shot is a composite stack of 200 images, showing the stars circling the celestial pole above the main auroral arc, and taken on Friday the 13th.

Aurora from October 13, 2013
A decent aurora across the north from home in southern Alberta, on Friday the 13th, October, 2017, though these frames were taken after midnight MDT. 3 seconds at f/2 and ISO 6400 wth the Sigma 14mm lens and Nikon D750.

This frame, from some 1300 I shot this night, October 13, captures the main auroral arc and a diffuse patch of green above that pulsed on and off.

You can see the time-lapse here in my short music video on Vimeo.

Friday the 13th Aurora from Alan Dyer on Vimeo.

It’s in 4K if your monitor and computer are capable. It nicely shows the development of the aurora this night, from a quiescent arc, through a brief sub-storm outburst, then into pulsing and flickering patches. Enjoy!


What all these scenes have in common is that they were all shot from home, in my backyard. It is wonderful to live in a rural area and to be able to step outside and see these sites easily by just looking up!

— Alan, October 16, 2017 / © 2017 Alan Dyer / AmazingSky.com 

 

Dawn Sky Delights


Aldebaran About to be Occulted by the Moon

It was one of those mornings when the sky was full of wonder.

After days and nights of smoke from unfortunate fires burning not far away, including in my favourite national park of Waterton Lakes, the sky cleared enough this morning, September 12, to reveal some fine sights.

At 6 a.m. the waning gibbous Moon passed in front of the star Aldebaran in Taurus. It is performing many such occultations of Aldebaran this year, but most aren’t well seen from any one location. This one was ideal, right from my backyard.

The lead image is a “high dynamic range” stack of several exposures showing the waning Moon and star set in some high haze adding the sky colours.

The star winked out behind the Moon’s bright limb as the Moon advanced from right to left (west to east) against the background sky.

Occultation of Aldebaran
Aldebaran nearing the limb of the Moon.
This shows a composite sequence, with images of the star taken every four minutes blended with a single image of the Moon. While it looks like the star is moving, it is really the Moon that is edging closer to Aldebaran.

The star reappeared from behind the dark limb of the Moon, but five minutes after sunrise, with the Moon in a bright blue sky. Still, the star stood out nicely in binoculars and in the telescope for this view.

Aldebaran Near the Moon in Day Sky
Aldebaran off the dark limb of the Moon.
Aldebaran is the point of light at right, just off the invisible edge of the Moon.

I shot stills and video, and compiled them into this short video.

Enlarge it to full screen to view it properly.

Meanwhile, over to the east the twilight sky was awash in planets.

Rocky Planets at Dawn with Labels (Sept. 12, 2017)
The line of dawn planets, with labels.
All the three inner terrestrial worlds were there: Venus, at top, Mercury below Regulus, and Mars lowest of the trio. Of course, a fourth terrestrial world is in the photo, too – Earth!

Mercury was at its greatest western elongation this morning, placing it as far from the Sun and as high in the sky as it gets, with this autumn appearance the best of 2017 for a morning showing for Mercury. Even so, you can see how Mercury is always low and easy to miss. However, this morning it was obvious to the naked eye.

Mars and Mercury will be in close conjunction at dawn on the morning of September 16.

Rocky Planets at Dawn (Sept. 12, 2017)

It was a fine morning to be up early and enjoy the solar system show.

— Alan, September 12, 2017 / © 2017 Alan Dyer / amazingsky.com

 

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

 

Mars and the Milky Way at Emerald Lake


The Milky Way over Emerald Lake, Yoho

The nights were short and never fully dark, but early June provided a run of clear nights in the Rockies to enjoy Mars and the Milky Way.

Weather prospects looked good for a run of five nights last week so I took advantage of the opportunity to shoot nightscapes from Banff and, as shown here, in Yoho National Park across the Continental Divide in B.C.

The lead image above is a sweeping panorama at Emerald Lake, one of the jewels of the Rockies. Though taken at 1:30 a.m., the sky still isn’t dark, but has a glow to the north that lasts all night near summer solstice. Even so, the sky was dark enough to reveal the Milky Way arching across the sky.

The mountain at centre is Mt. Burgess, home of the famous Burgess Shale Fossils, an incredible collection of fossilized creatures from the Cambrian explosion.

The image is a panoramic stitch of 24 segments but cropped in quite a bit from the original, and all shot with an iPano motorized panning unit. Each exposure was 30 seconds at f/2.2 with the Sigma 24mm lens and Nikon D750 at ISO 4000. One short exposure of the lodge was blended in to reduce its light glare. The original, stitched with PTGui software, is 15,000 x 9,000 pixels.

The Milky Way at Emerald Lake, Yoho
The Milky Way over the side pond at Emerald Lake, Yoho National Park, BC., from the bridge to the Lodge. This is a stack of 8 x 25-second exposures for the foreground (mean combined to smooth noise), and one untracked exposure for the sky (to minimize trailing), all at f/2.8 with the Rokinon 14mm lens and Canon 6D at ISO 6400.

The view above, a single frame image, shows the view to the south as the Milky Way and galactic centre descend toward the horizon over the south end of the lake. Lights from the Lodge illuminate the trees.

Reflections of Mars at Emerald Lake
Mars, at right, reflected in Emerald Lake at twilight in Yoho National Park, BC, June 7, 2016. This is a single 6-second exposure at f/3.2 with the Sigma 20mm lens and Nikon D750 at ISO 100.

The next night (above) I was at the same spot to shoot Mars in the deepening twilight, and reflected in the calm waters of Emerald Lake, with Cathedral Peak at left.

Reflections of Cassiopeia at Emerald Lake
This is a vertical panorama of 4 segments, taken with the iPano unit, and with each segment a 30-second exposure at f/2.2 with the Sigma 24mm Art lens and Nikon D750 at ISO 4000. Stitched with Adobe Camera Raw.

Another multi-frame panorama, this time sweeping up from the horizon, captures Cassiopeia (the “W”) and the rising autumn constellations reflected in the lake waters.

Vega is at top, Deneb below it, while the stars of Perseus and Pegasus are just rising.

It was a magical two nights in Yoho, a name that means “wonderful!” Both by day and by night.

— Alan, June 9, 2016 / © 2016 Alan Dyer / AmazingSky.com

 

Glows and Streaks in the Spring Sky


The Spring Sky over the Pioneer Farmstead

How many sources of skyglow can you pick out here?

There are at least five:

• the Milky Way (at left),

• green airglow (below the Milky Way),

• all too prevalent light pollution (especially reflected off the clouds coming in from the west at right),

• lingering blue twilight across the north (at left and right), common in May and June from my northern latitude,

• and even a touch of aurora right at the northern horizon at far left.

In this scene from May 28, the Milky Way arches over an abandoned pioneer farmstead from the 1930s and 40s near my home in southern Alberta.

Mars (very bright and in some clouds) and Saturn shine at lower centre, while Jupiter is the bright object in clouds at right just above the old house.

Arcturus is the brightest star here at upper right of centre, made more obvious here by shining through the clouds. The Big Dipper, distorted by the map projection used in the this panorama, is at upper right.

Technical: This is a 360° horizon to zenith panorama taken with the iPano motorized panning unit, using the 24mm lens at f/2.8 and Nikon D750 at ISO 6400, for a stitch of 28 panels, in 4 tiers of 7 segments each. Stitched with PTGui. South is at centre, north to either end. The original is 25,700 x 7,700 pixels.

Just after I shot the panorama I captured the International Space Station passing directly overhead in one of several passes this night.

ISS Pass #2 (May 28/29, 2016)
The second Space Station pass of May 28/29, 2016, at 1:40 a.m., with cloud moving in adding the glows to all the stars. Taken with the 8mm fish-eye lens from home. The Big Dipper is high in the west at right. Mars is bright at bottom, to the south. Several other satellites are in the sky as well. This is a stack of 3 exposures, each 2.5-minutes with the camera on the Star Adventurer tracker.

At this time of year the ISS is lit all night by the Sun that never sets for the astronauts. We see the ISS cross the sky not once but several times in a night at 90-minute intervals.

While the sky near solstice is never dark at my latitude, it does have its compensations and attractions.

— Alan, May 29, 2016 / © 2016 Alan Dyer / AmazingSky.com

 

Mars Bright in the Spring Sky


Spring Sky over the Badlands Panorama

Mars is now shining brightly in the evening sky, as close and as bright as it has been since 2005.

Look southeast to south after dark and you’ll see a brilliant reddish “star.” That’s Mars, now at opposition, and retrograding slowly westward each night through Scorpius into Libra.

My image above captures Mars set in the entirety of the northern spring sky, complete with the arch of the Milky Way, twilight glows to the north (at left), some satellite trails …

… and Mars itself as the brightest object just right of centre shining above the landscape of Dinosaur Provincial Park.

Just to the left of Mars is Saturn, while below both is the star Antares in Scorpius, for a neat triangle of objects. Jupiter is the bright object in Leo at far right.

Technical: I shot the lead image on the evening of May 25. It is a 360° and horizon-to-zenith panorama stitched from 44 images, taken in 4 tiers of 11 panels each, shot with a motorized iOptron iPano mount. I used a 35mm Canon lens at f/2.8 for 30-second exposures with the Canon 6D at ISO 6400. I stitched the images with PTGui. The original image is a monster 32,500 pixels wide by 8,300 pixels high.

Mars at Opposition Rising over the Badlands
This is a stitch in Adobe Camera Raw of 9 segments, each with the Canon 35mm lens at f/5.6 and Canon 6D at ISO 800.

I shot the panorama above earlier in the evening, when Mars and Saturn were just rising in the southeast at left, and the sky to the northwest at right was still bright with twilight.

This shows the geometry of Mars at opposition. It lies opposite the Sun and is so rising at sunset and directly opposite the sunset point. The Sun, Earth and Mars are in a straight line across the solar system with Earth in the middle and as close to Mars as we get.

Actual date of opposition was May 22 but Earth is closest to Mars on May 30. That’s when it will look largest in a telescope. But to the unaided eye it appears as a bright red star.

Whether with eye or telescope, have a look!

— Alan, May 27 / © 2016 Alan Dyer / www.amazingsky.com 

Mars in the Moonlight


Mars in the Badlands

Mars is approaching! It now shines brightly in the midnight sky as a red star in Scorpius.

You can’t miss Mars now. It is shining brighter than it has since 2005, and is about to come as close to Earth as it has in 11 years as well.

Mars is now approaching opposition, when the Earth comes closest to Mars, and the Sun, Earth and Mars lie along the same line. Opposition date is May 22. That’s when Mars shines at its brightest, at magnitude -2.1, about as bright as Jupiter. Only Venus can be a brighter planet and it’s not in our sky right now.

A week later, on May 30, Mars comes closest to Earth, at a distance of 75 million kilometres. That’s when the disk of Mars looks largest in a telescope. And you will need a telescope at high power (150x to 250x) to make out the dark markings, north polar cap, and bright white clouds on Mars. 

Mars in the Moonlight (May 13, 2016)
Mars above Antares, with Saturn to the left, low in the south on May 13, 2016, in the moonlight of a waxing quarter Moon, from home in Alberta. This was one week before opposition and two weeks before closest approach, so Mars is particularly bright and red. However, from my latitude of 50° N Mars appears low in the south. This is a single 15-second exposure, untracked, at f/2.5 with the 35mm lens and Canon 6D at ISO 2000.

In these views, I show Mars shining as a bright reddish star low in my western Canadian sky. I shot the lead image from Dinosaur Provincial Park on May 16. The image just above was from my backyard the night before.

This week, Mars is passing between Beta and Delta Scorpii, two bright stars in the head of Scorpius, as the red planet retrogrades westward against the background stars.

Saturn shines to the east (left) of Mars now, with both planets shining above the red giant star Antares in Scorpius. In these photos they form a neat triangle.

Even without a telescope to magnify the view, it’ll be rewarding to watch Mars with the unaided eye or binoculars as it treks west out of Scorpius into Libra this spring and summer. It stops retrograding on June 30, then starts looping back into Scorpius, for a rendezvous with Antares and Saturn in late August.

This little compilation of time-lapse movies shows Mars, Saturn, and the rest of the sky, rising into the southeast and across the south on two nights this past week.

Be sure to explore Mars this month and next, whether by eye or by telescope. It’s the best we’ve seen it in a decade.

It’s next close approach in 2018 will be even better, though Mars will appear even lower in our northern sky.

– Alan, May 17 / © 2016 Alan Dyer / amazingsky.com