Hazy Astronomy

As I've mentioned before, this year is designated as International Year of Astronomy (IYA). To that end, the Royal Astronomical Society of Canada (RASC - I've been a member for more than 30 years) is undertaking many public activities, free for all to take part in. Worldwide, there are many astronomy associations and educational institutions involved in the same activities.
After several locally scheduled events were "rained out" lately, last night turned out to be more promising. A clear evening was predicted by Attilla Danko's "ClearDarkSky" program which uses data from Environment Canada's weather forcasting system.
Things turned not quite as clear as predicted - there were thin, hazy clouds drifting across the sky all evening. However, they were transparent enough to show the brighter objects, one of which was the planet Saturn. Three of us were slated to run this meeting, and two of us had committed to set up our own telescopes at the H.R. McMillan planetarium for this date, so I set up my Celestron C-8 in front of the Gordon Southam observatory. The third member in our group operated the observatory telescope itself.
This year, Saturn's rings are seen almost edge-on. That's a consequence of the tilt of Saturn's axis of rotation with respect the plane of its orbital plane and generally all the major planets' orbits. This presents some interesting viewing since some of Saturn's moons, most of which orbit Saturn in the same plane as its rings, can occasionally be seen crossing Saturn's disk, along with their respective shadows. Since the hazy clouds had a detrimental effect on seeing some of the very fine details through the telescopes, such an event would be somewhat difficult to perceive. However, the rings and Saturn's bright moon Titan were easily visible. To the left you see what Saturn and Titan looked like as seen through a telescope, at a magnification of about 90 power. Click on the picture for a larger view.
There were more than 100 people who took advantage of the occasion - some had been attending a show at the planetarium, others just happened to be out for a walk. Many had never had a look through an astronomical telescope, and were very impressed about what could be seen. It's amazing how interested people are in what's going on in space; many just don't know how to meet people with similar interests. So this get-together fulfilled its primary purpose of bringing these people together. Some enquired about how they could get more involved. Here is one possibility: the RASC member meetings and sky observing sessions are open to the public, and are free. If you become a member, there are a number of privileges which you'll enjoy. In Canada, for more information, go to http://www.rasc.ca/, and pick the link to your closest local centre. If you live elsewhere, look for an astronomy club in your area - IYA is a worldwide effort.

Turning 3000

About 3 years ago, my brother-in-law's brother and wife gave us an exercise bike which they were replacing with a more up-to-date version. At the time, it's speedometer indicated about 300 miles. It is a totally mechanical bike, with an adjustable tension roller pressing against the wheel, which makes it possible to simulate mountain "grades" and, if adjusted properly, will make us work hard. On the days when weather or a particluar time commitment prevents us from going for our walk, we use this bike for about one half hour - and for myself, I adjust it so that I work up a real sweat. On average, I cover about 9.3 miles in that half hour (according to the odometer). If I do any less, I'm not working hard enough. Both my wife and I are making pretty good use of it, but since she gets quite a bit of exercise around the house, it is I who does the bulk of the pedalling on the bike (90%, or so).



In the winter, the bike is used almost daily. In the summer we're much more likely to walk - our neighbourhood is hilly, and a good walk is good exercise. In any case, the other day, when I was doing my usual half hour on the bike, the odometer turned 3000 miles (it's an older bike, and still calibrated in miles). This means that we've added about 2700 miles (a bit more than 4300km) to its total use. That's the distance from Vancouver, BC (our city) to Halifax on the East Coast. It also means that the bike has been used about 320 times by us (it's getting close to the equivalent of one year's worth of half-hour per day pedalling). I never thought we'd "bike" all the way across Canada - we did it "virtually", of course. Luckily, the bike doesn't simulate any inclement weather "along the way".

The bike works just fine - I've oiled the various bearings, chain, and especially the pressure roller about 3 times. I expect it to last a lot longer still.

Looking for Life

Most of the mainstream media don't pay much attention to the efforts being made regarding our search for the possibility of life elsewhere in the universe - including our own solar systems. Now and then, you are made aware of temporary highlights (the Kepler space telescope launch just yesterday, for example), but in general, ongoing coverage is not available.

You can find this kind of information on the websites maintained by the space agencies involved in these endeavours.

Here are some links for proposed space missions related to this topic:

Europa Jupiter System Mission
http://www.jpl.nasa.gov/video/index.cfm?id=808

Titan Saturn System Mission
http://www.jpl.nasa.gov/video/index.cfm?id=810

This is the International Year of Astronomy. Astronomy is closely involved with the search for life elsewhere. Amateur and professional astronomers are making many varied efforts to promote the awareness of this ancient science. Here, for the area where I'm at home, are a couple of links indicating the locations where observation of the sky, seminars on various astronomical topics, and other related efforts are taking place :

The Royal Astronomical Society of Canada, Vancouver Centre
http://www.vancouverastronomy.com/

Local meetings
http://astronomy.meetup.com/131/

There are similar events scheduled all over the world. Check you local astronomy club or association for more details.

More window views

A few days ago, during one of the frequent rain squalls which are common in our city, a momentary break in the clouds was the cause of a beautiful rainbow. The picture on the left was taken from the front stairs. The rainbow appears high in the sky, because it was late in the day, around 20 minutes before sunset.






This picture was taken through the living room window. Notice the secondary rainbow, the intense colours, and the difference of the sky colour inside and outside the rainbow.











Last night, Venus (at the moment the evening star) and the Moon were in conjunction, an astronomical term for the appearance of two or more objects close to each other in the sky. It does not mean that they were physically close, it is just a view from our perspective on Earth. In reality, Venus was about about 140 times further away than the Moon. Click on the picture for a larger view. The view is through my double-paned office window. It was taken with a 200mm Sigma zoom lens, set at 200mm. This is an enlarged section of that image.


Venus also shows a crescent, just like the Moon (both somewhat distorted, due to the window glass). If you have a reasonable pair of binoculars (7x50 or 10x50, say), and mount these on a photo tripod, or hold them very steady, you'll also see the tiny crescent of Venus. You'll be able to look at Venus for the next couple of weeks, or so - weather permitting. Look for the brightest star in the west after sunset. Its crescent will grow a bit larger and get thinner as Venus moves closer to Earth towards the line between Earth and the Sun. This also means that Venus will set in the west sooner and sooner after sunset. On March 27, it will pass north of the Sun (don't try to look for it then - you could damage your eyesight if you look directly at the Sun!) and then become the morning star.

A Picture Postcard day

Today is one of the days which keep my wife and me "glued" to the window. The scenery is one of the reasons why we love living in our house.

At left, you see a picture of Grouse Mountain, one of the "North Shore mountains" in Vancouver, taken with a 200 mm lens, through our double-paned living room window. The triangular area slightly above centre is the upper ski area, sometimes called the "upper cut".




This is the same area taken through a C-90 Celestron telescope, for which I have the appropriate adapters to attach my Canon Rebel XT digital SLR camera. This turns the telescope into a 1000mm f11 lens. Because there is no electrical connection between the telescope and the camera, the automatic features built into the camera cannot be used - manual focussing and exposures are required. The exposure for this picture was 1/4000 of a second at ASA 400. If you click on the picture to enlarge it, and look closely, you can see some tiny dots (skiers) near the lower left of the ski area, and the plume (or dirty exhaust?) from a (snowmaking?) machine at the top. Being a creature of comfort, I took this picture through the living room window as well. That affects the "definition" of the image, because the window glass is optically not perfect. I used Photoshop to increase the contrast somewhat, and also sharpened the picture a bit, to help overcome the effects of the window on the image.

Regarding the skiers visible in the picture, I'm always amazed about how small people are when compared to the grandeur of nature. Even Grouse Mountain, at about 1250m (4000 ft) a modest mountain, dwarfs a human being by a huge margin.

Woodpeckerwar

As Derek mentioned in his blog, the woodpecker which last year decided to use our kitchen stove exhausts on the roof as territorial markers, has come back to re-establish his claims. I had wrapped the exhausts with bubble-wrap to discourage this "disturbing" behaviour (the 'pecker sometimes "rings the bell" just a little after sunrise), but the ravages of time destroyed that wrap. I removed the remnants some time ago.

For the last couple of days, the 'pecker has again made sure that we couldn't sleep in. So today I decided to frustrate him - and to allow us to extend our morning bedtime. I purchased some wire mesh and fashioned it into a kind of "cage" which now covers the exhausts (see picture of one). The cage is secured to the exhaust by means of an appropriate piece of wire coathanger, so that this undoubtedly clever little monster can't lift it up and out of the way. We'll soon see whether peace has returned.

More on the lens adapter

In my previous post, Derek's comment regarding the labelling of the focal length of the lenses involved in my test of the new adapter I bought for my Rebel XT, I came to the conclusion that the labelling on my Sigma 18-200mm zoom lens was the "full-frame" equivalent value. Yesterday, I repeated a couple of the flower basket shots, but in addition, I also took some long-distance shots to compare the Bausch and Lomb and Sigma 200mm performance.

Figure 1 shows the flowers taken with the Sigma lens at 200mm again, and figure 2 is an image of the same flowers, taken the Bausch and Lomb 200mm from the same position. The B&L image is obviously larger.

In figure 3 (the Grouse Mountain ski area as seen from our front window), taken with the Bausch and Lomb lens at 200mm, and the same picture (figure 4) taken with the Sigma lens at 200mm, there is no difference in scale. What's the reason?

Well, I neglected to take account of something I routinely do when I use the Rebel XT on one of my telescopes to take pictures. Depending on the accessories used in the process, the effective focal length of the telescope changes considerably, depending on the focussing adjustments required to get a sharp image. The pictures of the flowers were taken at a distance of about 2.5 meters (appr. 8 ft.), which is the closest distance to which the B&L lens can be focussed. The B&L lens focuses by moving the entire set of lens elements forward for close-up work; the Sigma lens adjust focus by changing relative positions of its internal lens elements. You can see the difference in the pictures of the B&L lens in its long distance (infinity) focus position (figure 5), and its close-up focus position (figure 6).

As you can see, the barrel length of the B&L lens in its close-up focus position is appreciably longer than when it is focused at infinity. The effect of the close-up position is that the lens appears to have a focal length of about 230mm, not 200mm. This naturally results in a larger image. The Sigma lens does not physically move lens "outward", and therefore maintains the 200mm distance from the camera's CCD. When both lenses are set to infinity, the scale of the pictures is identical.

This means, contrary to what I said to Derek in my reply comment, that both the Sigma and the B&L lenses are labelled with their correct focal length - there is no full-frame equivalent marking on the Sigma lens. Click on each picture to see it in larger format.

Figure 1
200mm Sigma zoom lens (flowers are 2.5 meters away)

Figure 2
200mm Bausch and Lomb lens from the same position as Sigma lens.

Figure 3
Grouse Mountain taken with the B&L lens at 200mm

(notice the snow-making plume near the top of the "cut")

Figure 4
Grouse mountain taken with the Sigma lens at 200mm
(snow-making plume has changed)

Figure 5

Bausch and Lomb at infinity (figure 3 focus)

      Figure 6

Bausch and Lomb at closest focus (figure 2)

Some examples of using a lens adapter

On January 16, Derek pointed to some interesting links. One of them relates to lens adapters. As Derek has mentioned in a previous blog, I used to be a studio photographer many years ago, and I have a 35mm film camera among my "collection" of things optical. That camera uses Pentax screw-mount type lenses, so it is about 40 years old. Derek's article prompted me to order a lens adapter for my Canon EOS XT Rebel digital SLR camera. At left, you see the adapter (bottom), and the three screw-mount lenses which I used in the photographic experiment described in more detail below. Not shown is a 2x "teleconverter" - an additional screw-mount lens which can be attached to any of the lenses shown, it "doubles" the focal length of all the lenses. The largest lens is a 200mm, f3.5 Bausch and Lomb lens, the smaller one is a 135mm f2.8 Bausch and Lomb, and the smallest a 55mm f1.8 Asahi Pentax lens.

The pictures below show is the effect of using the "full frame" screw-mount lenses have on the scale of the pictures generated in the Rebel XT, which has a "crop-factor" (APS-C dimensions are 25.1 × 16.7 mm and have an aspect ratio 3:2) type of CCD (it plays the role of the film in film cameras, see Derek's post on Aug 16, 2008). In general, the full-frame lenses act as lenses which appear to have a larger focal lengths, when used with a crop-factor cameras. The effect of a crop-type CCD is equal to "cropping" a 16x25mm section of a full (24x36mm) frame, seemingly "enlarging" a section of the full-frame image. Here are some examples:

This is picture taken with a 18-200 Sigma zoom lens at 200mm and f6.3 - the "upper limit" of what this crop-frame lens is designed for. This lens has optical stabilization features, which makes hand held, longer exposure less like to be blurred by camera motion caused by my hand.

For comparison, this is the image from the full-frame 135 mm Bausch and Lomb lens, also set to f6.3 (nowhere near its "upper limit" of f2.8). The scale of the image is almost identical to that of the 200mm Sigma lens, above (just a tiny amount smaller). This lens has no image stabilization. Exposures are calculated and made just like I used to do in the days of "non-electronic" film cameras. There is no electrical connection to the automatic features of the EOS Digital Rebel. There is no automatic focus - it's done through the viewfinder.

Here we have the image from the 200mm full-frame Bausch and Lomb lens, again at f6.3 (also not the limit of f3.5). You can see the image is larger than the 200mm Sigma image. The "cropping" effect shows - the 200mm Bausch and Lomb lens acts more like a 300mm crop-factor lens..

Here we have a picture taken with the 200mm Bausch and Lomb lens to which the 2x teleconverter has been attached. This makes it 400mm full-frame lens, which acts like 600mm crop-frame lens. Of course, the use of the teleconverter makes the f-stop markings on the lens incorrect. The doubling of the focal length requires a fourfold increase in exposure. In this case, to achieve the approximate equivalent of f6.3, I set the lens itself to f3.5 (its upper limit).

This is a picture taken with the 55mm Asahi lens, again at f6.3 (the upper limit if f1.8). This is a reasonably scaled standard image, with a reasonable angle-of-view. The effect is that of a 80mm crop factor lens. Derek presented me with a 50mm f1.8 Canon EF lens a couple of years ago, which gives a wider view angle, at the same speed (f1.8) as this lens.

The conclusion I draw from all this is that for the price of the lens adapter (about $75.00 after shipping and exchange rates are factored in), I have gained the ability to use my high-quality full frame lenses on my Digital Rebel. The equivalent Canon lenses would cost many hundreds of dollars. It's true that the "old" lenses do not have any of the interactive features of the lenses designed for use with EOS cameras, but this only means that I have to fall back on the techniques which I had to use in the the days of mechanical film cameras (calculating light levels, depth of field, exposure times, etc. in my head), before taking the picture. One advantage of the digital camera is the ability to display the picture just taken on the view screen, in the days of film, you had to wait until the film was developed and printed. In many ways, mentally calculating the required parameters prevents the "mental laziness" to which I succumb too readily when using the automatic features on my digital camera.

The use of the teleconverter effectively doubles the number of focal length capabilites, but there is a fair overlap with my crop-factor lenses, so that some of the combinations are essentially available twice. In any case I now have a fair number of possibilities. Generally, fixed focal length lenses tend to have a better optical quality, and much lower f-ratios - i.e. they are "faster", than the zoom lenses that commonly come with digital cameras of the Digital Rebel level, so if a given picture has to have critical definition, or is taken in low-light conditions, the use of the full-frame lenses may be a better option.

A Planetary Perspective

As I mentioned yesterday, we spent a few days in Mexico (Puerto Vallarta) recently. During that time, and considering my interest in things astronomical, I took a picture of a loose alignment of three planets, and the Moon, visible for a short period after sunset. The planets were Jupiter, Mercury, and Venus (in order of increasing distance from the horizon).

To see the details better, click on each picture.

Jupiter, the largest planet is closest to the horizon, actually seen through a light cloud. Mercury is slightly to the left of, and a little higher than Jupiter. The bright spot to the left of the Moon at the top of the picture, and somewhat lower, is Venus. The leftmost picture shows the actual scene; the right picture is the annotated version.

This is an interesting demonstration in planetary perspective. In this picture, Jupiter, the Solar System's largest planet (it has a mass equal to 318 times Earth's mass), is six times farther away from us than Mercury. Mercury is the planet closest to the Sun, Venus is next closest (our Earth is third) and Jupiter is the fifth of the major planets orbiting the Sun. Jupiter orbits five times farther out from the Sun than Earth. As shown in the picture, even that far away (we're talking about 900 Million km - 560 Million miles), Jupiter shows up brighter than Mercury. Mercury is around 160 Million km - 100 Million miles away. Venus (almost equal in size to Earth) is at this time about 110 Million km - 70 Million miles away. The closest is the Moon, "only" about 380 thousand km - 236 thousand miles away.


Quite apart from these scientific aspects, it was a pretty picture in its own right - certainly quite different from our wintery scene; the temperature at the time I took these pictures was about 22 degrees Celsius (72 F). On the left, you see a wider-angle view. Both Jupiter and Mercury are located to the left of the topmost dark cloud in the lower right (which seems to point straight to them).

We were staying with close friends, one block away from the beach, a couple of minutes' walk to this beautiful scene on Banderas Bay.

^

Away from the snow

I haven't posted anything since Christmas - we were away until yesterday, in Puerto Vallarta, Mexico. To our surprise, on our return, we still found nearly as much snow near our driveway as the day we left. Highly unusual for this city.

Derek had shovelled the snow out of our driveway, so it was easier to get back into the house. He said it was good exercise, and we certainly appreciated his efforts.

Derek had seen no reason for us not to go on this trip - he said that he felt well enough, and also took a little trip to Victoria while we were away. While he didn't enjoy the same kind of weather we had, it is nice to see that he can take some "time off", too.

Common sense?

I haven't written a "letter-to-the-editor" type of note to the media in a very long time, but today I wrote one to the "opinion page" of our local newspaper. It concerns the meteor seen in the sky over Alberta and Saskatchewan on November 20 of this year. Here's the gist of my (expanded for this blog) note:

On Tuesday, Dec.23, page B2 - "Metorite fall could yield scientific gold" - the article regarding the Nov. 20 meteor seen in Alberta/Saskatchewan (picture at left), I read with great interest, and a sense of sad dismay, that the more than 100 meteorites collected are all "...part of a 10-tonne, 10-kilometre-wide meteorite that broke up on impact with the atmosphere, spawning brilliant flashes of light that caught many eyes" (from the 9th paragraph in that article).

To begin with, a meteorite is defined as that part of a meteoroid which is found on the ground after travelling through the atmosphere. A meteoroid is the solid, original body before it encounters the atmosphere. The process by which this body disintegrates when it travels through atmosphere and which results in the 'brilliant flashes of light', and other associated phenomena (heat, ionization, occasionally sound) is called a meteor.

If the meteoroid (taken as a cube to make the basic calculations easy) had indeed been 10 km (about 6.2 miles) diagonally across, it would have had a mass of millions of tons (around 500 million - roughly equivalent to 1 trillion pounds); it would have struck the Earth almost totally intact, and caused a conflagration similar to what many scientists think happened on the Yucatan peninsula 64 million years ago, with the subsequent extinction of many species. If the 10-ton mass (about 20,000 pounds - i.e. about three GM Hummers) is taken as approximately correct, then the meteoroid that hit us, again taken as cube, would have been about 1.6 metres along each side. The meteorites shown in the newspaper's picture with Dr. Hildebrand appear to be of a "stony" nature - approximately 2.5 times the density of water. 10 tonnes of water is equal to 10 cubic metres of water, by definition - 1 cubic metre of water is equal to 1 ton. A 10-ton cube of water would measure about 2.15 metres along each edge. The "stony" equivalent cube of stone would therefore be 1/2.5th of 10 cubic metres, i.e. about 4 cubic metres. This would be a cube measuring about 1.6 metres on each side. How can one equate 500 million tons with 10 tons, or a cube of approximately 5.8 kilometers (5,800 meters) along one edge to 1.6 meters along the edge, or a trillion pounds to twenty thousand?

In reality, of course, the meteroid would not be a cube, but of some irregular shape. That makes calculations like these far more complex, but there is no getting away from the masses of material and the orders of magnitude involved.

What dismays me is the apparent incomprehension of and lack of innate feeling for the relationships between size, mass, weight and other physical characteristics and properties of the things that surround us, perhaps mixed in with lack of understanding regarding the metric system. It is as though common sense has left the authors and/or editors involved in the kind of published nonsense seen in the media far too often.

I gain little consolation from knowing that this kind of "innumeracy" is all too common. Not a month goes by in which I don't see such misrepresentation and misunderstanding in the newspapers or other media. Is this due to a lack of teaching in school?

This whole thing may be of no interest to anyone, but I had to vent my spleen here.

Merry Christmas

This year, we used only the top two/thirds of our artificial Christmas tree (Derek opted for a natural tree this year). We think it looks just as nice this year, and we did not need to move a lot of furniture to accommodate it. The heirloom decorations (many handmade) make it beautiful.

Merry Christmas, and a Happy and Healthy New Year to all of you!

The "full" Christmas tree

The tree this year



















A hand-made decoration. This one came from Erlyne's mother. Erlyne was a bridesmaid at our wedding, 44 years ago, and my wife and she are still in almost daily contact. She's family.

A quick year

It seems that each year goes by faster. It seems like last week that the previous winter was here. Right now, the snow is falling and I'll have to shovel some of it to clear the sidewalk. The grandchildren went off to school, taking along their snow slider board - they'll have a great time at school, where there is a small hill.

I have a theory why the years appear to go faster as you get older: each minute that goes by is a larger percentage of the rest of your life. So, enjoy what you can, you may not have the chance again.