Lake O’Hara is one of the gems of the Canadian Rockies. O’Hara is the biggest of several stunning lakes in the area, and is a popular year-round destination. In the summer, it is accessible by bus or foot, 12km up a road. In the winter the road is a few hours by ski, and makes a great destination with light touring gear or even ultra-light cross-country skis.
For fans of the great outdoors, the months between summer and winter – October, November and December – are generally known as Shoulder Season, Drinking Season, or Renovation Season. The days are rapidly getting shorter, and by mid November it’s dark by 7 in the evening, making it a great season to get out and enjoy the night sky!
Elizabeth Parker Hut
There are several places to stay in the Lake O’Hara area, including the historic lodge, the campsite, and two Alpine Club of Canada Huts. Abbot Pass Hut is a fantastic stone building perched at the col between Mt. Victoria and Lefroy, but is only accessible in the summer. On this trip we stayed at the Elizabeth Parker Hut, built in 1919 and located a few 100m from the lake, which is easily reached by ski during the winter.
Skiing in up the road the sky is mostly clear and weather sunny and beautiful, with a few puffy clouds sticking around to give some colour to the sky during sunset.
Before scrolling down too far, having a properly adjusted monitor is key to viewing these night photos accurately. Adjusting the Contrast and Brightness of your monitor should allow you just barely distinguish between the different shades of gray on the following strip.
This time of year the days are short and the nights long, so after a relaxing dinner and some sitting around swapping stories and drinking wine I pop my head out the door, around 7:30, to find that the sky to the SE is now completely clear of clouds and thick with stars. The Milky Way is a glowing band rising above Odaray Mountain to the SW and arching straight overhead to disappear behind Mts Huber and Lefroy to the east. Stunning!
It takes about 15 minutes to setup the tripod, align the AstroTrac to north, setup the camera and start shooting. Capturing all 30 frames takes at least two hours, during which time a few Taurid meteors sail overhead, and a few folks from the hut come out to enjoy the spectacle with me.
Click to zoom into the high-resolution image.
This image was built up from about 30 frames taken with a 50mm lens, set at f4.5 to increase sharpness, and guided for 3 minutes at ISO 400. The sky conditions were nearly perfect, with minimum sky glow, not much condensation, and no clouds or wind. Even the temperature was pleasant, maybe -10C.
This view covers about 90 degrees from south (right) to east (left) and about 90 degrees up to the zenith.
How Many Stars?
With your naked eyes on a clear night, far from any source of light pollution, you can see roughly 4000 stars. More like 4500, actually, depending on your latitude, time of year, sky darkness and atmospheric conditions.
Star brightness is measured in stellar magnitude, a logarithmic brightness scale established, like much of astronomy, in ancient Greece. Under very dark skies (more than 50km from a town and 200km from a city) the human eye can see stars to about magnitude 6. This image is comprised of 3-minute exposures, in which I was able to see stars and galaxies to about magnitude 11. According to this page, that means the camera captured about 200x as many stars as are visible to the naked eye.
To estimate the number of stars visible here, I took 100×100 pixel samples of the image and counted the stars in each of those little boxes. Tedious, yes.
The density of stars varies tremendously across the sky, from the very rich regions looking into the plane of the Milky Way, around Cygnus, to the sparser regions around Pisces, looking about 60 degrees out of the galactic plane.
The full image is about 80 megapixels, and by dividing it roughly into regions by density of stars and then plugging the sample counts into a spreadsheet… results in an estimate of about 1 million stars in this image. Not bad! But still only 1/500,000th of the estimated 100-1000 billion stars in our galaxy.
Humans have been mapping the stars for thousands of years, well before the invention of the telescope. The classic work is the famous Almagest, written by the Greek scholar Ptolemy in the 2nd century AD, and contains a catalogue of 1022 stars.
The Royal Observatory, in Greenwich, England was founded in 1675 with the purpose of measuring the celestial longitude (east/west angle) and declination (north/south angle) of stars for use in maritime navigation. The Atlas Coelestis was published in 1729 and contained over 3000 stars.
A 44-year long project by the Bonn Observatory in Germany from 1859 to 1903 resulted in the Donner Durchmusterung (BD) catalog containing approximately 325,000 stars.
The first satellite-based star survey mission was Hipparcos, launched in 1989 and in operation until 1993, which resulted in a catalog of over 2.5 million stars published in 2000.
The successor to the the Hipparcos mission is the Gaia satellite, which was launched in December 2013 and is designed to measure the location, distance and proper motion (velocity of the star within the galaxy) of 1 billion stars. The accuracy of measurement is astonishing, with the brighter stars being located to the width of a hair at 1000km!
The completely-misnamed planetary nebulae have nothing to do with planets at all, but are actually the remnants of stellar explosions, and usually appear small, round and faintly coloured; hence looking like a planet in small telescopes.
Messier 27, the Dumbbell Nebula, was captured clearly in these exposures. It was the first planetary nebula to be discovered, by Charles Messier in 1764, and is one of the youngest deep-sky objects, between 10,000 and 48,000 years old.
NGC 6826 (Cygnus right arm) and NGC 7662 (Pegasus north) are much smaller and dimmer nebulas, barely visible in this image, but both have the same green/cyan colour. With much bigger optics than a 50mm lens, their true nature as massive stellar explosions is revealed.
The green colour is ionized oxygen (double-ionized actually), from the deeper parts of the original star, where oxygen was created through a variety of nuclear reactions that start with the fusion of hydrogen, the most basic element.
It is this stellar nuclear fusion that is responsible for the creation of all the heavier (than hydrogen) elements. These elements are then blown out into space during a nova or supernova explosion, and seed the Universe for the next generation of stars and solar system formation.
You and I, the oxygen we breath, the food we eat, and everything else around us was formed in the heart of stars that died billions of years ago; one of the most astounding revelations of modern physics!
Around the constellation of Andromeda are three of our galactic neighbours. The largest and most easily visible is M31, the Andromeda galaxy, a truly magnificent spiral galaxy with roughly twice as many stars (1000 billion) as our Milky Way (100-400 billion). At 260,000 light-years, it is also roughly 2.5x as wide as our galaxy, although according to a recent study, the Milky Way is thought to have roughly the same mass, apparently containing more dark matter.
Orbiting the great Andromeda galaxy is a satellite galaxy, M110, the faint smudge to the right in the above image. It is an elliptical galaxy, 15,000 light years in diameter, only 1/20 the size of Andromeda.
A much “deeper” image (22 hour exposure instead of only 3 minutes!) reveals the vastness of this whirlpool of 1000 billion stars. Galaxies, made of billions of stars, look like hazy fog for the same reason that clouds do, which are made of billions of water droplets.
Messier 33, the Triangulum galaxy is both both physically and visually smaller than Andromeda. About 50,000 light-years in diameter, it is about half the size of our own Milky Way, and the third-largest galaxy in our local group of galaxies, after Andromeda and the Milky Way. With “only” 40 billion stars, it is considered a small (but not dwarf) galaxy, but because it’s relatively close to us and angled nicely, it is much-studied and imaged by professional and amateurs alike.
Our solar system sits about 1/2 way from center of the Milky Way, which is why it appears as a hazy band across the sky: we are looking into the pancake.
Until the 1920s it was not clear whether the other spiral-shaped nebula visible in the sky were within our galaxy or outside of it, a great debate on the nature of the universe which was resolved in 1925 when Edwin Hubble was able to measure the distance to the Andromeda Galaxy and determined that it was much further away than any of the stars in our galaxy, thus proving that it was it’s own “island universe”.
Unlike star catalogs, we only started making galactic catalogs in the 1960s, with the first catalog containing over 29,000 galaxies. The currently running Galaxy Zoo project, launched in 2007, is a crowd-sourced effort to classify galaxies that were imaged as part of the Sloan Digital Sky Survey, and has over 50 million galaxies in their database to date.
The total number of galaxies in the Universe is truly mind-boggling, and by staring a dark patch of sky for a long time, the Universe reveals itself. This summer, July 2014, NASA released an update to the Hubble Ultra Deep Field image, containing around 5500 galaxies from a patch of sky that is much, much smaller than the moon. The total exposure time was 2 million seconds (over 555 hours!) taken over 10 years by the Hubble telescope. And each one of those fuzzy spots is a galaxy containing billions of stars…
A view into the (nearly) infinite!
– Darren Foltinek, 2014