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)