Dark Skies

[glenc]

Are you looking for some dark skies?
These maps will help you find it.

They are from:
The World Atlas of the Artificial Night Sky Brightness
http://www.lightpollution.it/worldatlas/pages/fig9.htm

[Lee]

My problem isn't not knowing where it is, it's finding the time to get out there! Isn't hard to find dark skies in Australia, only need to really avoid about 10 cities....

[Ric]

Very interesting maps indeed, it looks like my areas of dark skies are slowly being overtaken, hopefully I will be safe from it for a few more years to come.

cheers

[okiscopey]

Here's part of the 'dark sky' image superimposed on a map of NSW - I was curious to see exactly where the 'dark grey-black' boundaries were located.

Expected this to be an easy job in Photoshop - semitransparent layer on top of base map and just re-size to make big light pollutions coincide with population centres. In fact had to use 'warp' transform (CS2) - the scale seemed to vary from place to place, but not in any way that seemed to do with different map projections.

The NSW composite map took an hour ... tried it with the whole of Australia but gave up - too many misalignments to cope with!

[Ric]

Thats fantastic Mike, you have done a great job with the superimposing of the two maps.

great work

[glenc]

Thanks Mike.
Why is Parkes so bright?

[Ric]

I noticed that Merimbula is a nice looking dark area, we have a holiday house down there with the C8. No imaging though just visual.

cheers

[okiscopey]

Yes, that's a bit odd. I've looked at another set of images and it looks like there's a top secret 'light pollution factory' a few km ENE of Parkes. I'm still working on it, will post images later, unless ASIO or SPECTRE gets to me first.

[okiscopey]

Glenc,

Attached is the Parkes area from Google Maps with bits of both the NASA 'Earthlight' map (http://antwrp.gsfc.nasa.gov/apod/ap001127.html) and the recent 'sky brightness' map superimposed.

As you can see in this more detailed view, Parkes (arrowed) produces the brightness you'd expect from a town of its size .. but what on earth is causing the big blob (and the one to the NW) 20 km ENE?

I looked at the satellite views of the areas on Google maps but there's nothing obvious there.

Interestingly, there's no sign of any brightly-lit area 20km ENE of Parkes on the NASA 'Earthlight' view, only on the 'sky brightness' map.

Anyone got any ideas?

[glenc]

Great stuff for ufo or conspiracy theories :rofl:

Probably a mistake on The World Atlas of the Artificial Night Sky Brightness

[Calin]

Yep, its a shredded weather balloon, though I hear tell of someone having seen some odd looking little green fellow with large eyes darting about the place - apparrently left in a hurry coz' there was no crops to play in and make some odd symmetrical shape on account of the drought.:whistle:

[okiscopey]

Hmmm! More investigations. The attached image shows the terrain E of Parkes with what I reckon is the approx location of the unexplained source of sky brightness (red circle). Possible contenders (dam, quarry - white arrows) seem too far north. I'm sure nobody else is following this thread, but it's got me so intrigued my next trip to darker skies than Sydney might include a side-trip to this UFO landing site.

Had trouble posting image recently, hope this one works.

[glenc]

Mike it might be the quarry or road works at night.

[Rodstar]

Thanks to all of those who have contributed to this most interesting thread.

I note with interest that Ilford (SPSP, near Rylstone) falls well within the second darkest patch only. Coonabarabran (other than in the immediate vicinity of the town) falls into the darkest category. Goes to show that there are darker skies than I have ever experienced still to enjoy. As others have said, shame they are so far away!

[h0ughy]

guys note the area near mururundi between muswellbrook and tamworth, its in the black, its high, has a few pubs, caravan parks hotels and has dark skies... lostock is also near dungog and gloucester, they are in the grey but closer to the edge than Illford

[ving]

interesting... whats the really polluted area off the east coast fo the south NZ island?

another ufo landing spot? ;)

[okiscopey]

Another anomaly!?!? Could be gas burn-off from an oil platform ... but I can't imagine such a thing exists in that location. Couldn't find any leads on the Internet. This is getting silly! I'm considering e-mailing Dr Perantonia Cinzano, the author of the 'night sky brightness' atlas to see if he has any answers.

[glenc]

It is probably a fishing fleet.

[okiscopey]

Yes that must be it.

I'd previously overlooked the FAQ page on the light pollution web site where this is mentioned:

http://www.lightpollution.it/worldatlas/pages/faq.html

Q: "What's all that light near the Falkland islands? For a small set of islands with more sheep than people, how can they possibly generate so much light?

A: Satellite data also record the offshore lights where oil and gas production is active (visible e.g. in the North Sea, Chinese Sea and Arabic Gulf), other natural gas flares (visible e.g. in Nigeria) and the fishing fleets (visible e.g. near the coast of Argentina, in Japan Sea and near Malacca). Note that their upward emission functions likely differ from the average emission function of the urban night-time lighting that we use so that the predictions of their effects have some uncertainty."

Still leaves the Parkes blob to be explained!

[Kal]

Great link.

For those of you that have google earth installed, it only takes about 3 minutes to overlay this picture onto google earth, and you can then switch the overlay on or off in the sidebar at your pleasure. Simply:

*Save the picture you want to overlay from the first thread in this post
*Open google earth and move the map over Australia/New Zealand, whichever is relevant for the overlay map you are pasting
*Click 'Add > Image overlay'
*In name field write 'Light Pollution', and click browse at the end of the 'Link' field. Browse to the .jpg file of the light pollution that you saved in step 1. Move the 'Transperancy' Bar to halfway between clear and opaque.
*To line up the picture, you can move the overlay by dragging it in the centre green box on your google map. You can adjust the size and line it up properly by dragging the four corners. Adjust it so that it lines up nicely.
Refer to this image for what it should look like: http://img180.imageshack.us/img180/8421/step1rw0.jpg
*Click OK and Voala!


For those that don't have google earth installed it can be downloaded for free from http://earth.google.com/

Here is a screenshot of what it looks linke now when I zoom into Sydney. My house is in the middle of the red zone :doh:

http://img218.imageshack.us/img218/9074/step2ur8.jpg

[Kal]

The patch to the NW looks like it is caused by a couple of quarries that are in the area. That very bright patch is bizarre, all I could think of was a bushfire at the time of mapping? On my google map overlay it appears to be directly over some forest area.

http://img295.imageshack.us/img295/6370/upload3mq0.png

[okiscopey]

I've e-mailed Dr Perantonia Cinzano to find out if the Night Sky Brightness Atlas is using 'averaged' or 'single date and time' data. If the latter, roadworks, bushfires and other ephemeral events could maybe affect the results. I've asked if he's come across any similar inland 'anomalies' which might help explain the Parkes one.