View Full Version : APOW: Astronomy Picture Of the Week

05-20-2009, 11:53 AM
This was taken last night looking north to Williams Lake. Over the years the city and the mills have installed thousands of street and yard lights, many of them sodium vapour. When the night started it was very clear and there was almost no sky glow even in the direction of town so I set up for an all night time lapse sequence similar, but longer, than the one I made recently.

As is often the case not long after I started taking frames clouds began to move in. In this case they came in from the northwest over the town first and are strongly illuminated by the mixture of mercury vapour and sodium vapour lighting. While it spoiled my time lapse session to some degree I did get an interesting contrast of colours between the night sky and the clouds.

I wonder how long it will take for those responsible for the design of lighting to realize that lighting up the sky is a total waste of energy?


05-20-2009, 12:51 PM

doesn't the camera have to rotate so the stars look stationary in your timelapse photos? if so, how come the trees aren't blurred?

you do take some cool photos!

andy b.

05-20-2009, 12:54 PM
It's a fairly wide angle lens and the exposure is only 40 seconds. With that lens it isn't enough time for the stars to show trails.

05-20-2009, 08:21 PM
When I first bought my house in Bolton, MA, in 1982, when I came home at night it was DARK and I had trouble finding the porch stairs. When I sold the place in 2007, it was so light in the sky at night you could see to walk around easily.

It's a big loss. In 1986 I went to Ayers Rock in Australia, and at night a multitude of stars came down to the horizon. An awe-inspiring sight.

05-20-2009, 08:25 PM
Cosmic Energy is free i heard evan.

05-20-2009, 08:27 PM
Yes it is Mike. I will be posting about that soon. I am still collecting performance data.

tony ennis
05-20-2009, 10:45 PM
I wonder how long it will take for those responsible for the design of lighting to realize that lighting up the sky is a total waste of energy?

As soon are their compensation is based upon energy conservation.

05-20-2009, 11:53 PM

Nice complementary colors, with the bluish night sky and the orange-tinged clouds.

I imported your photo into Elements and blew it up 32X to see the pixels as squares. The star colors really become apparent at this magnification. What causes the different colors?

05-21-2009, 12:47 AM
The color is an indicator of the age of the star. As fusion proceeds up through the elements the color of the star changes to reflect the spectographic lines of those elements. Young stars are fusing hydrogen and that produces copious amounts of high energy photons in the blue end of the spectrum. Old stars are green as they are loaded with iron and iron plasma gives off strong green lines. Red stars are old stars that are expanding, cooling off and no longer fusing so they are radiating according to their black body temperature as they expand.

Give me a few minutes to find one and I will post a picture that really shows the different colors.

05-21-2009, 01:57 AM
Here is a good example. It's short exposure but at high magnification with no drive on so the stars formed trails. The scope was very slightly out of focus which actually enhances the colour by expanding the area for the eye to see.


05-21-2009, 02:28 AM
Isn't that cool? I love it when I'm working on the farm. It's several thousand acres with no lights and all the neighboring farms are the same way. You can actually see the blurry band from the milky way. Coming from the city, I had no idea how magnificient the night sky is.

I was really surprised at how fast the stars move when looking through a 16" catadioptric telescope. I bumped the switch for the tracking while climbing the latter one night and was puzzled when the star seemed to float out of the eye piece in a matter of a few seconds. I though the mount locks were loose and the whole scope was moving.

05-21-2009, 02:40 AM
I have the camera running again tonight. It's looking like it might stay clear all night so as long as I don't have a serious dew problem I just might get a dusk 'til dawn movie tonight. I have the camera running on an ac adapter and an 8 gig card so that won't be a problem. Hopefully it will work as this is the last chance with no moon and dark sky until August.

05-21-2009, 03:08 AM
Nothing beats the magic of a clear night sky.
I am lucky to be out in the boonies far enough to appreciate the beauty of a dark and clear night sky just about any time the weather permits. Sometimes I whine and moan about living in the sticks when I can't find tooling locally, but when I look up at night I realize I am truly blessed.

I do take some trips, especially in the winter, that take me to places without a light bulb for at least a hundred miles...simply amazing!
Hard to describe to someone who has not had the good fortune to observe it first hand.

Have fun Evan, we appreciate you sharing the photos.

05-21-2009, 10:13 AM
Oh well, no luck last night. We had a lot of snow and rain yesterday so even though it was clear last night the camera first developed a severe amount of dew and then froze up solid. It doesn't hurt the camera but it sure doesn't take pictures well in that conditon.

That is one of the things that makes this hobby both challenging and satisfying. It isn't easy to get the perfect shot but when you do it is worth the trouble. It's also a very handy excuse for making things you can't buy.