Right Angle Moon


Saturday night was a fine evening for witnessing the geometry of the night sky.

This is sunset on the evening of the autumnal equinox, September 22, 2012, with a first quarter Moon in the sky. The image illustrates the geometry of the quarter Moon’s position, which is always 90° away from the Sun, a quarter of the way around its orbit in its monthly cycle.

In this case, because the Sun (at right) was on the equinox position on the ecliptic, it was setting due west this night (something it does only on the dates of the fall or spring equinox). This put the quarter Moon (at left) 90° away, due south at sunset.

Draw a line from the Moon to your eye (the camera) and then back out to the Sun and it forms a 90° right angle. This geometry holds true for any quarter Moon, but being equinox the Sun and Moon were nicely aligned due west and south, making their right angle arrangement more obvious.

I took this shot from the grounds of the Rothney Astrophysical Observatory on the occasion of their monthly Open House.

– Alan, September 23, 2012 / © 2012 Alan Dyer

 

Star Party Sunset in the Badlands


A hundred or so stargazers were treated to a beautiful sunset in the badlands of the Red Deer River valley on Saturday night.

This was the setting for the annual Alberta Star Party, at a campground north of Drumheller, Alberta, amid the late Cretaceous sediments of the badlands. This is big sky country.

Earlier in the week the night sky was clear and inviting. But this night the clouds served only to provide a fine sunset. They failed to disappear after nightfall. However, on a such a night, a good time is still had by all as everyone enjoys the company of fellow stargazers during the last of the fine weather before star party season ends for another year.

I took this 360° panorama with a handheld camera, and stitched the segments in Adobe Photoshop CS6.

– Alan, September 16, 2012 / © 2012 Alan Dyer

 

Mercury Rising Over Calgary


Mercury is elusive but here it is, showing up as a speck over the skyline of Calgary, as it begins its best evening appearance of the year, rising a little higher into the twilight sky each night for the next few evenings.

To find it, follow the line down from the Moon and then bright Jupiter and Venus at upper left and continue that line to the lower right. Just to the right of the tallest building (the new Bow tower) and just above the rooftops there’s a tiny dot of light. That’s the inner planet Mercury. It’ll get higher in the first week of March but not by much. Mercury is bright. It’s just not very high and is easy to miss.

But with Mercury coming into view, and with Venus and Jupiter so prominent now in the evening, and Mars now bright in the east after sunset – look for a red star – we have a nice array of 4 naked eye planets across the sky at once. Saturn comes up later after midnight now. So you can see 5 naked eye planets in one night.

It’s a great evening sky show now in early March.

– Alan, March 1, 2012 / © 2012 Alan Dyer

A Prairie Palette of Earth and Sky Tones


Following up on my previous post, here is the wide-angle scene of that same winter moonrise, taken at sunset on January 8, 2012.

This was a spectacular and truly “amazing sky,” with the last rays of the setting Sun illuminating the clouds and the rising Full Moon coming up in the pinks and blues of twilight. It is the big prairie sky at its best.

The wide scene captures dark cloud shadows converging toward the point opposite the Sun, near where the Full Moon sits. These are “crepuscular rays,” a common sight at sunset or sunrise.

— Alan, January 8, 2012 / Image © 2012 Alan Dyer

 

Sunset in the City — This is Only a Test!


This is one for the time-lapse geeks!

One of the trickiest subjects for a time-lapse sequence is a smooth and seamless day-to-night transition. Exposure times vary from fractions of a second before sunset to several seconds at night fall.

How to do it? Manually shifting exposures is too much work and prone to error. Putting the camera on Automatic can work but inevitably results in an effect known in the time-lapse world as “flickering.” The camera’s automatically-judged exposures aren’t consistent from frame to frame so the final movie shows minor bright/dark flickering, making it look jerky.

For this test sequence of sunset over the Calgary skyline, I tried a new toy for the first time, as a solution.

The device is called the Little Bramper (for Bulb Ramping). It is a custom-made intervalometer that fires the camera shutter every few seconds (at whatever interval you desire). Nothing new there. But what’s unique is that it can be set to slowly increment the exposure time by as little as 1/1000th of a second from frame to frame, gradually increasing the exposure (“ramping” it) to accommodate the darkening scene. The result is a smooth transition from day to night with no flickering.

This was my first use of the Bramper and it wasn’t without its glitches. The shortest exposure the Bramper can provide (it always controls the camera thru its Bulb setting) is about 1/10th of a second (I had no idea camera shutters can fire as quickly as that even on Bulb).

But at the beginning of a sequence like this, with a bright sky, achieving that exposure (still quite long) means using a small f-stop, a slow ISO speed, or a neutral density filter, or all of the above. But as the sky darkens and exposures lengthen, exposures would become too long to fit within the desired interval between frames (typically no more than 5 to 10 seconds for a smooth sequence). So, to shorten the exposures you then have to open up the lens, switch to a faster ISO, or remove the ND filter, while also commanding the Bramper to quickly reduce its exposure time, all in one exposure cycle (i.e. 5 to 10 seconds) so as not to lose or ruin frames. Takes some coordination and practice (hit the Bramper’s button, adjust the camera, all within 5 seconds), and I didn’t get it right the first couple of times.

But overall, for a first test, the sequence turned out very well. The $80 Little Bramper does the job, though it does take careful monitoring through the sequence, not just to perform the exposure swaps, but to also watch that the ramping rate (adjustable on the fly) matches what the scene is doing and you aren’t under- or over-exposing. It’ll take a little more practice, but the results certainly are worth it.

It’s another neat tool in the time-lapse arsenal.

— Alan, August 10, 2011 / Movie © 2011 Alan Dyer

The Great Lone Land


This is one of the great places for evoking the wide open spaces of the high plains. Here we are looking south over the Milk River and the rock formations of Writing-on-Stone Provincial Park in Alberta to the peaks of the Sweetgrass Hills in Montana. The buildings at right are the modern reconstructions of the late 1800’s North West Mounted Police outpost that guarded Canada from the illegals from the U.S. (!) coming up Police Coulee smuggling whiskey from Montana into Canada.

The time is just after sunset, as the last light of the Sun still illuminates the clouds. This is the magic hour for photography, and for taking in the solitude of the “Great Lone Land” as author William Francis Butler described it in his book of that title in 1872.

As Butler wrote, “No ocean of water in the world can vie with its gorgeous sunsets; no solitude can equal the loneliness of a night-shadowed prairie…”

— Alan, July 27, 2011 / Image © 2011 Alan Dyer