Three Galaxies and Comet - question (APOD 30 Mar 2007)

Post a reply


This question is a means of preventing automated form submissions by spambots.
Smilies
:D :) :ssmile: :( :o :shock: :? 8-) :lol2: :x :P :oops: :cry: :evil: :roll: :wink: :!: :?: :idea: :arrow: :| :mrgreen:
View more smilies
BBCode is ON
[img] is ON
[url] is ON
Smilies are ON
Topic review
   

Expand view Topic review: Three Galaxies and Comet - question (APOD 30 Mar 2007)

by mttghew » Fri Mar 30, 2007 8:44 pm

Just think, up until around the turn of the 20th century, every human being who had ever lived, no matter the location, could see the night sky unhindered by artificial light. Now it's almost the opposite. We have to travel to remote places simply to see the night sky as it really is. Amazing. Have we actually blotted out the stars, like in those corny old movies in which the villain inevitably says something like "I will blot out...THE SUN...mwhahah." In this case the stars, but you get the idea.

Anyway, thanks for the response (my first post on this board). I got the heads up about the "picture of the day" web page from the bad astronomy site (http://www.badastronomy.com/intro.html). I'm still trying to get over that video from several days ago that showed the moon crossing the sun. :shock:

by iamlucky13 » Fri Mar 30, 2007 5:33 pm

The photographer says that except for the color contrast, the picture is very much like what he saw:
This image is, from my point of view, very realistic and is very near to what I have in my mind with only one exception. The human vision has very low ability to see colors in low light conditions and therefore my sensation during the night was mostly B&W.
http://www.zam.fme.vutbr.cz/~druck/Astr ... 0-info.htm

by iamlucky13 » Fri Mar 30, 2007 5:30 pm

It's not embedded in the image, but the link on the photographer's name will take you to his personal webpage.

The particular image and basic photo data is here:
http://www.zam.fme.vutbr.cz/~druck/Astr ... 0-info.htm
This image is a composition of 13 images in total taken with super wide angle lens covering approximately 100°×100° angle of view. The lower part of the image consists of 7 images, the upper part of 6 images. Except for the Milky Way and the McNaught comet, both Small and Large Magellanic Clouds are visible in this image. This image is, from my point of view, very realistic and is very near to what I have in my mind with only one exception. The human vision has very low ability to see colors in low light conditions and therefore my sensation during the night was mostly B&W.
That page also says it was 30 seconds at F/2.8, ISO 3200 with a 17mm lens on a Canon EOS 5D.

He's got a lot of other great pictures of McNaught here:
http://www.zam.fme.vutbr.cz/~druck/Astr ... 0-info.htm

Comet and Three Galaxies (APOD 30 Mar 2007)

by golana » Fri Mar 30, 2007 4:16 pm

Hi,
Do you know the camera exposure info for this picture?

Regards,

Golana

by Andy Wade » Fri Mar 30, 2007 4:11 pm

NoelC wrote:I don't mean to go against Andy, but under truly dark skies and after an hour or two for one's eyes to adjust to the dark (i.e., become maximally sensitive to light) the sky can seem almost as bright and the Milky Way as detailed as what's being shown in this image. It's not like a neon sign, but it's amazing to see nonetheless.

The key is not to look at any bright light - not even that from a flashlight - for at least an hour.

And the moon must be nowhere in the sky. This is why astronomy parties are held on new moon weekends.

It is true that there are very few places left on the planet with virtually no light pollution. Astrophotographers routinely subtract the light pollution in their photos digitally, as not everyone enjoys skies like those shown in the photo.

There is actually a scale of light pollution levels called the "Bortle" scale. Note the wording of the two darkest levels:

Bortle level 1 (darkest): Gegenschein visible. Zodiacal light annoyingly bright. Rising milkyway confuses some into thinking it's dawn. Limiting magnitude 7.6 to 8.0 for people with exceptional vision. Users of large dobsonian telescopes are very happy.

Bortle level 2 (second darkest): Faint shadows cast by milkyway visible on white objects. Clouds are black holes in the sky. No light domes. The milky way has faint extentions making it 50 degrees thick. Limiting magntiude 7.1 to 7.5.

The only time I've ever seen skies as good as Bortle level 2 was at the Grand Canyon over a decade ago.

This might interest you:
http://www.inquinamentoluminoso.it/worl ... s/fig2.htm

-Noel
I'd agree with that actually. :)
Most people cannot see anything like as much detail because of the amount of light pollution, and bl00dy clouds of course.
However, stick with it for a bit and allowing your eyes to adjust until you get your night vision, and yes it's still pretty amazing. 8)
I've yet to see any colours, which are also depicted in the picture. And Of course there's the question of concentration. You really have to concentrate to see that level of detail. Its quite hard to keep up with the naked eye. You often have to just shut your eyes to rest them for a bit.
I've spent an evening or two over the years watching for Leonid meteors etc and it can be quite a strain. We were well prepared too. We laid in the open air in sleeping bags on camp beds and were up on the moors well away from car headlights, which are the worst offendors IMO.

by NoelC » Fri Mar 30, 2007 3:54 pm

I don't mean to go against Andy, but under truly dark skies and after an hour or two for one's eyes to adjust to the dark (i.e., become maximally sensitive to light) the sky can seem almost as bright and the Milky Way as detailed as what's being shown in this image. It's not like a neon sign, but it's amazing to see nonetheless.

The key is not to look at any bright light - not even that from a flashlight - for at least an hour.

And the moon must be nowhere in the sky. This is why astronomy parties are held on new moon weekends.

It is true that there are very few places left on the planet with virtually no light pollution. Astrophotographers routinely subtract the light pollution in their photos digitally, as not everyone enjoys skies like those shown in the photo.

There is actually a scale of light pollution levels called the "Bortle" scale. Note the wording of the two darkest levels:

Bortle level 1 (darkest): Gegenschein visible. Zodiacal light annoyingly bright. Rising milkyway confuses some into thinking it's dawn. Limiting magnitude 7.6 to 8.0 for people with exceptional vision. Users of large dobsonian telescopes are very happy.

Bortle level 2 (second darkest): Faint shadows cast by milkyway visible on white objects. Clouds are black holes in the sky. No light domes. The milky way has faint extentions making it 50 degrees thick. Limiting magntiude 7.1 to 7.5.

The only time I've ever seen skies as good as Bortle level 2 was at the Grand Canyon over a decade ago.

This might interest you:
http://www.inquinamentoluminoso.it/worl ... s/fig2.htm

-Noel

Re: Question about March 30 Picture of the Day

by Andy Wade » Fri Mar 30, 2007 7:25 am

mgton wrote:So I was wondering if that picture is representative of what the naked eye would see. That's probably a pretty idiotic question, but I have never seen a sky like that. I've always been told that in order to really see the nights sky you must view it from a secluded area free of artificial lights, but I have never actually done it. If that is what can be seen, I have really been missing out.
No. The picture requires a long exposure to gather all the light.
You can see similar 'detail' through a telescope, but not all the details in that picture at the same time.
I've 'star gazed' right in the middle of the Australian desert where the nearest light source is over 100 miles away, and the amount of stars visible is staggering, but you can't really see the detail shown in very long exposure pictures like this with the naked eye.
Shame really.

Three Galaxies and Comet - question (APOD 30 Mar 2007)

by mttghew » Fri Mar 30, 2007 5:36 am

So I was wondering if that picture is representative of what the naked eye would see. That's probably a pretty idiotic question, but I have never seen a sky like that. I've always been told that in order to really see the nights sky you must view it from a secluded area free of artificial lights, but I have never actually done it. If that is what can be seen, I have really been missing out.

Top