Zodiacal Band – The Amazing Sky

April 1, 2019April 1, 2019

Dinosaur Park in the Dark

Winter Sky Setting in Twilight at Dinosaur Park

There’s a slogan used in the U.S. National Parks that “half the Park is after dark.” It is certainly true at Dinosaur Provincial Park in Alberta.

Last Friday night, March 29, I spent the evening at one of my favourite nightscape sites, Dinosaur Provincial Park, about an hour’s drive east of my home. It was one of those magical nights – clear, mild, dry, and no mosquitoes! Yet!

I wanted to shoot Orion and the photogenic winter sky setting into the evening twilight over the Badlands landscape. This was the last moonless weekend to do so.

I shot some individual images (such as above) and also multi-panel panoramas, created by shooting a series of overlapping images at equal spacings, then stitching them later at the computer.

Winter Sky Setting at Dinosaur Park Panorama — This is a 240° panorama stitched from 17 segments, all with the 24mm Sigma Art lens and Nikon D750 in portrait orientation, each segment 20 seconds at f/1.4 and ISO 3200. Stitched with Adobe Camera Raw.

There’s a narrow window of time between twilight and full darkness when the Milky Way shows up well but the western sky still has a lingering blue glow. This window occurs after the normal “blue hour” favoured by photographers.

The panorama above shows the arch of the winter Milky Way but also the towering band of the Zodiacal Light rising out of the twilight and distant yellow glow of Calgary. Zodiacal Light is sunlight scattering off meteoric and cometary dust orbiting in the inner solar system, so this is a phenomenon in space not in our atmosphere. However, the narrow streak is an aircraft contrail.

Spring Sky Panorama at Dinosaur Park — A 360° panorama of the spring sky over the Badlands of Dinosaur Provincial Park, Alberta. This is a panorama of 12 segments taken with the 14mm Sigma Art lens and Nikon D750 in portrait orientation, all for 30 seconds at f/2.8 and ISO 4000. Taken at 30° spacings. Stitched with PTGui.

Later that night, when the sky was fully dark I shot this complete panorama showing not only the Milky Way and Zodiacal Light to the west, but also the faint arc of the Zodiacal Band continuing on from the pyramid-shaped Zodiacal Light over into the east, where it brightens into the subtle glow of Gegenschein. This is caused by sunlight reflecting off interplanetary dust particles in the direction opposite the Sun.

Both the Band and Gegenschein were visible to the naked eye, but only if you knew what to look for, and have a very dark sky.

The Winter Stars and Zodiacal Light at Dinosaur Park — This is a panorama stitched from 3 segments, all with the 24mm Sigma Art lens and Nikon D750, for 20 seconds at f/2.2 and ISO 4000. Stitched with Adobe Camera Raw.

A closeup shows the Zodiacal Light in the west as the subtle blue glow tapering toward the top as it meets the Milky Way.

It takes a dark site to see these subtle glows. Dinosaur Park is not an official Dark Sky Preserve but certainly deserves to be. Now if we could only get Calgary, Brooks and Bassano to turn down and shield their lights!

Spring Sky RIsing at Dinosaur Park Panorama — A 180° panorama of the spring sky and constellations rising in the east over the Badlands of Dinosaur Provincial Park, Alberta on March 29, 2019. This is a stitch of 6 segments, each with the 14mm Sigma Art lens and Nikon D750 in portrait mode, each 30 seconds at f/2.8 and ISO 4000. Stitched with PTGui.

A closeup facing the other way, to the east, shows the area of sky opposite the Milky Way, in the spring sky. The familiar Big Dipper, now high our spring sky, is at top with its handle pointing down to Arcturus and Spica (just rising above the horizon) – remember to “arc to Arcturus, and speed on to Spica.”

Leo is at right of centre, flanked by the Beehive and Coma Berenices star clusters.

Polaris is at left — however, the distortion introduced by the panorama stitching at high altitudes stretches out the sky at the top of the frame, so the Dipper’s Pointer stars do not point in a straight line to Polaris.

The faint Zodiacal Band is visible at right, brightening toward the horizon in the Gegenschein.

I shoot images like these for use as illustrations in future eBook projects about stargazing and the wonders of the night sky. Several are in the works!

Clear skies!

March 15, 2015

The Ghostly Glows of a Truly Dark Sky

A truly dark sky isn’t dark. It is filled with glows both subtle and spectacular.

Last night, March 10, I drove up into the heart of the Gila Wilderness in southern New Mexico, to a viewpoint at 7,900 feet in altitude. I was in search of the darkest skies in the area. I found them! There was not a light in sight.

The featured image is a 180° panorama showing:

– the Zodiacal Light (at right in the west)
– the Milky Way (up from the centre, in the south, to the upper right)
– the Zodiacal Band (faintly visible running from right to left across the frame at top)
– the Gegenschein (a brightening of the Zodiacal Band at left of frame, in the east in Leo)

The Zodiacal Light, Zodiacal Band, and the Gegenschein are all part of the same phenomenon, glows along the ecliptic path – the plane of the solar system – caused by sunlight reflecting off cometary and meteoric dust in the inner solar system.

The Gegenschein, or “counterglow,” can be seen with the naked eye as a large and diffuse brightening of the sky at the spot exactly opposite the Sun. It is caused by sunlight reflecting directly back from comet dust, the scattering effect greatest at the point opposite the Sun.

The Zodiacal Light requires reasonably dark skies to see, but the fainter Zodiacal Band and Gegenschein require very dark skies.

Now is prime season for all of them, with the Moon out of the way, and the Zodiacal Light angled up high in the western as twilight ends. In March, the Gegenschein is now located in a relatively blank area of sky in southern Leo.

The Milky Way is much more obvious. Along the northern winter Milky Way here you can see dark lanes of interstellar dust, particularly in Taurus above and to the right of Orion. Red nebulas of glowing gas also lie along the Milky Way, such as Barnard’s Loop around Orion.

– Orion is at centre, in the south, with Canis Major and the bright star Sirius below and to the left of Orion. Canopus is just setting on the southern horizon at centre. It barely clears the horizon from 32° North latitude.

– To the right of Orion is Taurus and the Pleiades star cluster at the top of the Zodiacal Light pyramid.

– Venus is the bright object in the Zodiacal Light at right, in the west, while fainter Mars is below Venus.

– At far right, in the northwest, is the Andromeda Galaxy, M31.

– Jupiter is the bright object at upper left, in the east, in the Zodiacal Band, and near the Beehive star cluster.

– The Zodiacal Light, Band and Gegenschein all lie along the ecliptic, as do Mars, Venus and Jupiter.

Glows on the horizon are from distant SIlver City, Las Cruces and El Paso. The brighter sky at right is from the last vestiges of evening twilight. Some green and red airglow bands also permeate the sky.

I shot this March 10, 2015 from the summit of Highway 15, The Trail of the Mountain Spirits, that twists and winds through the Gila Wilderness.

It was a stunning night, clear, calm, and silent. Just me under the ghostly glows of a truly dark sky.

NOTE: I first published this March 11 but had to republish this blog March 15 after WordPress deleted the original post in a software bug. Thanks WordPress!

March 20, 2013

The Ghostly Glow of Gegenschein

The band of light at right is the familiar Milky Way. But what’s that faint stream of light to the left? It’s called the Gegenschein.

My last blog showed an image of the Zodiacal Light in the west. In fact, that glow extends up and continues all the way across the sky as a very faint stream of light at the threshold of vision called the Zodiacal Band. But at the place in the sky 180° opposite the Sun the Band intensifies to become a diffuse patch of light. It’s easy to see with the naked eye from a dark site if you know to look for it, and where it is likely to be. Last week, it was sitting below the constellation of Leo, in an area of sky that is pretty blank. So any faint glow stands out.

As with Zodiacal Light, what you are seeing is sunlight reflected off comet and asteroidal dust, but for the Gegenschein (German for “counterglow”) the light is coming from dust opposite the Sun that is scattering light back toward us and the Sun, mirror-like. The back-scattering effect makes the dust appear a little brighter at the point opposite the Sun.

Spring is a good time to spot the Gegenschein (true for the northern or southern hemisphere) as it then lies in a sparse area of sky away from the Milky Way. But you need a moonless sky and a dark site free of manmade light pollution. It and the fainter Zodiacal Band are among the sky’s most subtle sights. Again, Atmospheric Optics has more details.

A bonus with this shot are some short streaks of light below and to the right of the Gegenschein. I think those are from geostationary satellites flaring at the anti-solar point as they, too, acted as mirrors briefly catching the sunlight. Being geostationary – likely communications satellites you aimed fixed dishes at – they stayed still while the stars and tracking camera moved, and so created streaks.

August 20, 2012August 21, 2012

Star Party Panorama

This image depicts a 360° panorama of the field and sky at the Saskatchewan Summer Star Party.

This was my first time shooting a nighttime panorama but it was easy. Just 12 exposures taken at 30° intervals panning around on a levelled tripod, in classic planetarium panorama style. Each exposure was 30 seconds at f/2 and ISO 3200 with the Canon 5D MkII and 24mm lens. It helps to have a high-quality fast lens.

North is at centre, south on either end.

The sky contains some interesting and subtle features that show up well in a wide-angle panorama like this:

– The bright summer Milky Way is setting at left in the southwest while the fainter winter half of the Milky Way is rising opposite, at right in the northeast.

– Jupiter and the Pleiades rise at right just off the Milky Way

– A meteor streaks over the trees at centre

– At centre, to the north, glows a faint yellow and magenta aurora

– The larger green glow left of centre is, I suspect, airglow rather than aurora. It has a striated structure, particularly at right of centre above the trees where it appears as subtle green and red bands arching across the northeast.

The sky this night was dark but did have a brighter than usual background, likely due to the presence of this faint airglow that the camera picks up better than the eye.

Even so, I can see another faint glow:

– A whitish band coming up from the northeast passing through Jupiter and below the Pleaides. That’s the Zodiacal Band, an extension of the brighter Zodiacal Light and caused by sunlight reflecting off cometary dust in the ecliptic plane.

The location of the panorama and star party was the Cypress Hills Interprovincial Park in southwest Saskatchewan, one of the darkest places in southern Canada.