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 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 

 

Toward the Centre of the Galaxy


Toward the Centre of the Galaxy

From southern latitudes the most amazing region of the sky shines overhead late on austral autumn nights. 

There is no more spectacular part of the Milky Way than the regions around its galactic centre. Or at least in the direction of the galaxy’s core.

We can’t see the actual centre of the Galaxy, at least not with the cameras and telescopes at the disposal of amateur photographers such as myself.

It takes large observatory telescopes equipped with infrared cameras to see the stars orbiting the actual centre of the Milky Way. Doing so over many years reveals stars whipping around an invisible object with an estimated 4 million solar masses packed into the volume no larger than the solar system. It’s a black hole.

By comparison, looking in that direction with our eyes and everyday cameras, we see a mass of stars in glowing clouds intersected by lanes of dark interstellar dust.

The top image shows a wide view of the Milky Way toward the galactic centre, taking in most of Sagittarius and Scorpius and their incredible array of nebulas, star clusters and rivers of dark dust, all located in the dense spiral arms between us and the galactic core.

Starclouds and Stardust – Mosaic of the Galactic Centre
This is a mosaic of 6 segments, each segment being a stack of 4 x 3-minute exposures at f/2.8 with the 135mm Canon L-Series

Zooming into that scene reveals a panoramic close-up of the Milky Way around the galactic centre, from the Eagle Nebula in Serpens, at left, to the Cat’s Paw Nebula in Scorpius, at right.

This is the richest hunting ground for stargazers looking for deep-sky wonders. It’s all here, with field after field of telescopic and binocular sights in an area of sky just a few binocular fields wide.

The actual galactic core area is just right of the centre of the frame, above the bright Sagittarius StarCloud.

Centre of the Galaxy Area
This is a stack of 5 x 5 minute exposures with the Borg 77mm f/4 astrograph and filter-modified Canon 5D MkII at ISO 1600, taken from Tibuc Cottage near Coonabarabran, NSW, Australia.

Zooming in again shows just that region of sky in an even closer view. The contrast between the bright star fields at left and the dark intervening dust at right is striking even in binoculars – perhaps especially in binoculars.

The visual impression is of looking into dark canyons of space plunging off bright plateaus of stars.

In fact, it is just the opposite. The dark areas are created by dust much closer to us, hiding more distant stars. It is where the stars are most abundant, in the dust-free starclouds, that we see farthest into the galaxy.

In the image above the galactic centre is at right, just above the small diffuse red nebula. In that direction, some 28,000 light years away, lurks the Milky Way’s monster black hole.

Milky Way Overhead Through Trees
This is a stack of 5 x 6-minute tracked exposures with the 15mm fish-eye lens at f/4 and Canon 5D MKII at ISO 1600. The trees appear to be swirling around the South Celestial Pole at lower right above the Cottage.

To conclude my tour of the galactic centre, I back out all the way to see the entire sky and the Milky Way stretching from horizon to horizon, with the galactic centre nearly overhead in this view from 3 a.m. earlier this week.

Only from a latitude of about 30° South can you get this impressive view, what I consider one of the top “bucket-list” sights the sky has to offer.

– Alan, April 17, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

Red Rivals in Scorpius


Red Rivals in Scorpius

Mars outshines his rival red star Antares in the heart of the Scorpion.

This was the view last night from my observing site in Australia, of red Mars shining near the red star Antares, whose very name means “rival of Mars.” But as Mars nears its closest approach to Earth next month it is already far brighter than Antares, easily winning the rivalry now.

The view takes in the head of Scorpius, one of the most colourful areas of the night sky when photographed in long exposures. Uniquely, Antares illuminates a nearby dust cloud with its light which is more yellow than red.

Other dust clouds reflect the blue light of hot young stars in this section of the Milky Way. Red nebulas are emitting their own light from glowing hydrogen.

The area around Antares is also streaked with lanes of dark dust that absorb light and at best appear a dull brown.

Mars reaches its closest point to Earth since 2005 on May 30. All through May and June Mars will shine as a brilliant red star near Antares. A telescope will provide the best view of the red planet we’ve had in a decade.

Saturn and Mars in Scorpius
This is a stack of 4 x 3 minute exposures with the 135mm telephoto lens at f/2.8 and filter-modified Canon 5D MkII at ISO 1600, shot April 14, 2016 from Tibuc Cottage, Australia.

While you are in the area aim your telescope a little to the east to catch Saturn, also in the area, though technically over the border in the constellation of Ophiuchus the Serpent Bearer.

In the view above, Saturn is the bright “star” to the left of Mars. Saturn reaches its closest to Earth in early June. Its rings are now wide open and a spectacular picture postcard sight in any telescope.

Scorpius Rising in Moonlight
This is a stack of 2 x 30-second exposures for the sky and ground, both tracked, plus a 30-second exposure through the Kenko Softon A filter to add the star glows to make the constellation pattern stand out. All with the 35mm lens at f/2 and Canon 6D at ISO 1600. Taken from Tibuc Cottage, Australia.

This final view shows Mars and Saturn rising with Scorpius in the moonlight from two nights ago. From my current latitude of 32° south, Scorpius comes up on his side.

— Alan, April 15, 2016 / © 2016 Alan Dyer  / www.amazingsky.com

Planets in the January Dawn


Waning Moon with Venus & Saturn in Twilight (Jan 6, 2016)

The waning Moon joined Venus and Saturn on a cold winter dawn.

This was the scene this morning, January 6, as the waning crescent Moon met with Venus (bright, at centre) and Saturn (below and left of Venus) in the cold morning twilight.

The grouping appeared above the stars of Scorpius. Antares is just above the treetops.

The top image is with the Canon 60Da and 50mm lens.

The view below, with the 135mm telephoto and Canon 6D camera, is from a half hour earlier before the sky began to brighten with morning twilight.

Waning Moon with Venus & Saturn (Jan 6, 2016)
The waning crescent Moon above Venus and Saturn (dimmer and below Venus) in the pre-dawn sky on January 6, 2016, taken from home on a cold winter morning at -20° C. This is a composite of a long exposure (8s) for the ground, a slightly shorter exposure (6s) for the sky, and shorter exposures for the Moon to avoid it being totally overexposed and to preserve the Earthshine. All with the 135mm lens and Canon 6D.

Venus passes very close to Saturn this weekend, with the two worlds appearing within a telescope field on the mornings of January 8 and 9. Get up early before sunrise and look southeast. Binoculars will provide a superb view.

Venus is hard to miss, but is now dropping lower each morning and will soon be gone from view as it ends its wonderful appearance as a morning star.

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

 

Evening Planet Parade in May


May 21 Venus & Moon

Three planets now shine in the evening sky, including Saturn now at its best for 2015.

Look west in the early evening to sight brilliant Venus in the twilight, and slightly dimmer Jupiter above it. On the evening of Thursday, May 21, look for the waxing crescent Moon below Venus in a wide pairing of the night sky’s two brightest objects.

The Moon appears between Venus and Jupiter on Friday, May 22, and near Jupiter two nights later on Saturday, May 23.

Meanwhile over on the other side of the sky, Saturn is rising at sunset.

May 20 Saturn

As the illustration shows, look southeast after sunset to see Saturn rising along with the stars of Scorpius. Saturn now outshines all the stars of Scorpius, including the red giant star Antares, shining below Saturn.

Saturn is at opposition this weekend, meaning Sun, Earth and Saturn are now lined up with Earth directly between the Sun and Saturn. That puts Saturn as close to us as it gets for 2015, and as bright as it gets.

Being opposite the Sun, Saturn is now rising in the southeast as the Sun sets in the northwest.

A nightscape of antique farm combines illuminated by starlight, with the Milky Way behind. The galactic centre area of Sagittarius and Scorpius lie to the south, with Saturn the brightest object at right. I shot this at the Visitor Centre at the Old Man on His Back Conservation Area in southwest Saskatchewan. The sky is a single 30-second exposure at f/2.8 with the 24mm lens and Canon 5D MkII at ISO 6400. The ground comes from a stack of 8 exposures to smooth noise, all part of a time-lapse/star trail sequence.
A nightscape of antique farm combines illuminated by starlight, with the Milky Way behind. The galactic centre area of Sagittarius and Scorpius lie to the south, with Saturn the brightest object at right. I shot this at the Visitor Centre at the Old Man on His Back Conservation Area in southwest Saskatchewan. The sky is a single 30-second exposure at f/2.8 with the 24mm lens and Canon 5D MkII at ISO 6400. The ground comes from a stack of 8 exposures to smooth noise, all part of a time-lapse/star trail sequence.

Here’s a shot of Saturn, Scorpius, and the Milky Way from early this morning, May 20, taken about 2:30 a.m. when Saturn and Scorpius lay due south. From the latitude of southern Saskatchewan where I am this week, Saturn and Scorpius graze the southern horizon, even in the middle of the night.

– Alan, May 20, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Moon and Twilight Planets over the Bow River


Moon with Antares, Mars & Saturn over Bow River

The waxing Moon shines between Saturn and Mars over the waters of the Bow River.

It was a beautiful autumn evening for watching the twilight showing of the crescent Moon accompanied by Saturn (at right of centre) and the pairing of Mars (at left, above) with his rival red star, Antares in Scorpius (at left, below).

The river is the Bow, with its headwaters at Bow Glacier in Banff.

To shoot this scene I drove to the grounds of the Blackfoot Crossing Historical Park south of Cluny, Alberta to take advantage of its viewpoint overlooking the Bow River and the heart of the traditional Siksika First Nations tribal lands.

It was here, in the valley below, that Treaty Seven was signed between Chief Crowfoot and Colonel James Macleod in September 1877. Today, a beautiful interpretive centre sits on the hillside at the heart of Blackfoot country.

– Alan, September 28, 2014 / © 2014 Alan Dyer