APOD: Earth at Night (2012 Dec 07)

[Bernard C Rooney]

Its not a problem. See my earlier post. Consider how far the light from the fire of stars travels to be seen. Its about the intensity of the light and the fact that the light source is exposed, whereas electric lights will often be shrouded because of being inside or under covers, and are often directional light (automobiles), which are not directed toward the Zenith. If all the human light was directed skyward without imediments of rooves, light covers and such the map would be far more brilliant. Because fires can give off such intense light, which is directed straight up as well as everywhere else, its easily picked up by the satellite camera and looks larger than what it is. We don't see the vast majority of stars that we should be able to because their direct light is obscured by dust, nebulae, etcetera. Line of vision is what its all about.

I light bonfires in my paddock every now and then and they light up paddock like the Sydney Cricket Ground!

I'm a little confused by the extraordinary patterns of illumination shown for north western Australia over a vast area of what we know is largely uninhabited desert. I know we are experiencing a mining boom in this region but accordingl to Google Maps ( yes, even if their aerials are five or more years old, that amount of infrastructure would surely be visible) there's little evidnet development to account for all the energy infrastructure. Compare the region's illumination with say, Indonesia? Anyone care to enlighten me, so to speak, and relieve me of my ignorance?

[Reynardo]

Wild fires?

You have to be joking. There isn't that much out there to burn! There's the odd stand of spinifex and similar desert flora, but not enough to have great sweeping quantities of light like that.

http://www.flickr.com/photos/67507070@N00/8254456210/ for a good look - you'd have a lot of trouble sustaining a fire out there, let alone getting the flames hot enough to show up on the camera.

[owlice]

Reynardo, really? You think others are kidding?? Evidence for wildfires in Australia is so easily found online that I think you must be joking (or something) to suggest they are impossible. Googling "Australian wildfires" will demonstrate that yes, they do occur, sometimes resulting in great devastation.

Check out these images of bushfires from other satellites; these are from NASA’s Aqua satellite:

Click to view full size image

Click to view full size image

And, you know, the other links already provided upstream. Plus many many more online.

[Wombat]

owlice - that first link are for the highly populated, and wooded east coast.

Your second link is for the tropical area of Northern Territory - while sparcely populated it is certainly very lush country up there!!

The "fires" in the middle of West Australia are in the Great Sandy Desert, Little Sandy Desert and the Gibson Desert.

http://upload.wikimedia.org/wikipedia/c ... eserts.PNG

They are called deserts for a reason and Sandy for a reason. Seriously anyone who has done the Gun Barrel Highway will tell you there are no trees out there only spinifex and small scrub at the utter best. I'm with Reynardo in asking for more detail please.

Bernard states that only intense light will show up therefore the movement of the bush fires are/is irrelevant hence no blured "lights' from the moving fires. There is way too much 'intense light in the picture given that if there is a fire out there it doesn't spot fire well. Spinifex does burn fast and hot therefore you would expect to see only the fire front and not too much behind.

Lastly Bush fires are usually finished in a few days. i would have thought from the point of accuracy they could have waited? (from previous apod pictures I have come to expect a high degree of pedantic thoughtfullness towards making sure anything posted I can rely on)

IMHO of course. (and please excuse spelling / grammer mistakes)

Cheers

(edited for typos)

[neufer]

Click to view full size image 1 or image 2

Thick Vegetation Fuels Australia Fires
October 7, 2011

<<Australia may be in for an intense fire season this spring and summer as the warm temperatures settle in. In late 2010 and early 2011, La Niña dumped flooding rains over the southern continent. The moist soil allowed thick grass to grow; now that the grass is drying out, it is fuel for fires. In Northern Australia, more than 150,000 square kilometers (58,000 square miles) have already burned.

These vegetation maps show the build-up of grasses and other plants during the autumn (April) and the return to more normal conditions in the spring (September). The images were made with data from the Advanced Very High Resolution Radiometer on the NOAA-18 POES satellite and show plant growth in April and September as compared to the average, long-term growth for each month.

The measurement is an indication of how dense and leafy plants are and how much photosynthesis is going on. In April, Australia was covered with much denser growth than normal as thick grasses grew, especially in the interior of the country. Growth was still high in September, but conditions were closer to average in many areas.

What happened to all of the plants during the winter? They are still there, but the satellite now sees fewer green, photosynthesizing leaves. And all that dead or dry plant matter could fuel fires. In fact, emergency authorities in Australia are warning residents that the risk of grassland fires is very high this year. Fuel loads may reach their highest levels in 30 years, said news reports. Though not as hot or intense as forest fires, grass fires spread very quickly and can be erratic, making them extremely dangerous.>>

[owlice]

I'm with Reynardo in asking for more detail please.

Did you read the information here? I had provided some of the relevant text from that page in an earlier post but not all of it; I assumed those interested would follow the link, which I had also supplied.

[BDanielMayfield]

I light bonfires in my paddock every now and then and they light up paddock like the Sydney Cricket Ground!

Yesterday morning when I saw this apod for the first time I too was going to post a question about the outback lights in western Australia, but by then several others already had. The wild and in some cases as shown by our mate Mr. Rooney manmade fires provide ample explanation.

[BDanielMayfield]

But IMO all this talk about lights were they ordinarily aren’t has diverted much of the discussion away from what the main point should have been:

Two words: Light Pollution!

No wonder I can't see more than half a dozen stars from my backyard.

This apod shows that billions of people cannot and may never be able to see the splendor of the Milky Way with the naked eye, a sight that is far more impressive than even the best photograph could ever be. If you don’t believe me then you’ve never seen it for yourself, which is sad. We need dark skies ya’ll.

Bruce

[rstevenson]

I see that the spacecraft passes "over the same point [on Earth] twice a day at about 1:30am and 1:30pm local time." So there will be just 22 night time images to work with, for any one spot on Earth, from those 22 days of data collection. So those who insist on the bushfire explanation for the many areas of bright light in Western Australia are effectively saying that a large part of the country was on fire during those two short spans of time. Yet a search of the web yields no such alarming sounding news. And both April and October are in the off-season for bushfires.

No, I'm not suggesting a conspiracy. But the image seems to be exaggerating a relatively minor natural occurance. An image of a single night (if the world was entirely clear that night) would show the same human presence on Earth without over-emphasizing the natural fires, and lightning storms, and other such movable occurrances.

Rob

[owlice]

~~~~~ sigh ~~~~~

The extent of the night lights in this area ["this area" being western Australia] is also a function of composite imaging. These new images were assembled from data acquired over nine days in April 2012 and 13 days in October 2012. This means fires and other lighting (such as ships) could have been detected on any one day and integrated into the composite picture, despite being temporary phenomena.

Because different areas burned at different times when the satellite passed over, the cumulative result in the composite view gives the appearance of a massive blaze. These fires are temporary features, in contrast to cities which are always there.

Emphasis mine, and that from the link I've supplied twice earlier in this thread.

I'll sit quite happily next to the NOAA and NASA scientists ("scientists have confirmed, there were fires in the area when Suomi NPP made passes over the region. This has been confirmed by other data collected by the satellite."), thank you very much.

If others want to seek out alternative explanations, have at it, but at this point IMHO it's on you to prove what is shown is something different than the explanation already given. Have fun with that!

[rstevenson]

~~~~~ sigh ~~~~~

...and other such disrespectful comments will not endear you to those scientists you want to sit next to. I said...

No, I'm not suggesting a conspiracy. But the image seems to be exaggerating a relatively minor natural occurance.

I don't think that rather mild stance warrants such a response.

Rob

[neufer]

Click to play embedded YouTube video.

~~~~~ sigh ~~~~~

...and other such disrespectful comments will not endear you to those scientists you want to sit next to. I said...

No, I'm not suggesting a conspiracy. But the image seems to be exaggerating a relatively minor natural occurance.

I don't think that rather mild stance warrants such a response.

Especially considering what owlice is being paid to do this

[owlice]

~~~~~ sigh ~~~~~

...and other such disrespectful comments will not endear you to those scientists you want to sit next to. I said...

No, I'm not suggesting a conspiracy. But the image seems to be exaggerating a relatively minor natural occurance.

I don't think that rather mild stance warrants such a response.

Rob

Rob, I agree with you: the image seems to be exaggerating a natural occurrence, and why it seems to be was explained -- to my satisfaction anyway -- on the page that says "the cumulative result in the composite view gives the appearance of a massive blaze." Did you follow the link to that page? Did everyone else who questioned that image on this thread?

I'm thinking that the answer to at least one of those questions is "no," hence the sigh. I'm weary.

I don't know that the point of the imaging is to "show the ... human presence" on our planet; I think rather it is one of the results of, rather than the reason for, the imaging, but fully acknowledge I could be completely wrong about that.

Especially considering what owlice is being paid to do this

I often have questions about APODs, and when I do, 99% of the time, following the links provided answers those questions, and if they don't, following subsequent links takes care of most of the remaining 1%. But maybe I'm incurious, gullible, or easily satisfied if I think the source (NASA, NOAA [even retirees from NOAA], etc.) reliable.

[ta152h0]

Si !

[rstevenson]

Rob, I agree with you: the image seems to be exaggerating a natural occurrence, and why it seems to be was explained -- to my satisfaction anyway -- on the page that says "the cumulative result in the composite view gives the appearance of a massive blaze." Did you follow the link to that page? Did everyone else who questioned that image on this thread?

I'm thinking that the answer to at least one of those questions is "no," hence the sigh. I'm weary.

You're weary because you do such a good job.

Yes, I followed all the links, and I learned a lot doing so. But I found others, one which told me the 22 passes by the satellite didn't occur during the usual fire season, another that told me this isn't even a particularly bad year for fires -- yet. Which is the only reason why I kept wondering about the extent and brightness of the fires as shown in this image. I'll give it a rest now, but only because I can't find anything else worth saying at this point.

Australia is on my short list of places to visit if I ever stop working long enough. Maybe I'll just go and see those fires in the desert for myself. I might come back converted!

Rob

[ta152h0]

it is also the home of the deadliest snakes..

[tekic545]

Fires don't sit in the same place when they burn. They move. Kind of like a comet. Taking 22 images of a comet 24 hours apart then combining the image stack would give the improbable impression of 22 comets all in a row.

So perhaps the earth at night image recorded 22 times (or some smaller but significant multiple) as many fires as actually existed. That wouldn't be a problem with the other components of the image. Well-gas flares and cities don't move.

Bob Gillette

[geoffreybrent]

Reynardo, really? You think others are kidding?? Evidence for wildfires in Australia is so easily found online that I think you must be joking (or something) to suggest they are impossible. Googling "Australian wildfires" will demonstrate that yes, they do occur, sometimes resulting in great devastation.

You may not have intended it as such, but when you start lecturing Australians about how "Australian wildfires" work based on your five minutes of Googling, that comes across as quite unnecessarily patronising.

We are very aware that Australia has a lot of wildfires. (We call them "bushfires", BTW). The reason we're finding the "fires" explanation rather baffling is that we also know enough Australian geography to be aware that those lights on the map are mostly in areas with names like "Gibson Desert", "Great Sandy Desert", "Little Sandy Desert", and "Great Victoria Desert", which don't have a lot of vegetation to burn.

I'm not saying the explanation is impossible - some parts of those deserts have enough vegetation to allow grass fires - but something as spectacular and widespread as depicted in this photo seems a little hard to believe, unless there's some quirk of the image creation process that acts to exaggerate them.

[one_iota]

WRT the West Australian fire explanation: this is plausible.

From the Australian Government's Sentinal web site (http://sentinel.ga.gov.au/acres/sentinel/index.shtml) is this screen shot of the continent of Australia showing "hotspots" during the month of October 2012. Note the density over the subject area.

[scruffy1]

i was amazed enough to finally subscribe to the site, having been a keen watcher of apod since last century

and as an australian i too am bemused at such illumination that is in the arse end of nowhere, but accept the explanations i have read

sadly it means that the value of such mapping to recognise how "city lights identify major population centers, tracking the effects of human activity and influence across the globe" when accuracy is significantly diminished by spurious light sources

and it demonstrates as others have said why we don't get to see the real marvel of space from where we mostly congregate (cities), as light pollution directly ruins the seeing

[Anthony Barreiro]

I live in San Francisco, in the middle of one of the bright patches on the west coast of North America. Fortunately there are relatively dark skies within an hour's drive of my home, and very dark skies within a day's travel. Even in the middle of the city, my back yard is dark enough to see a lot. This morning before dawn I was looking at M13 and M51 through binoculars. The Moon, planets, double stars, and star clusters show up well even through light pollution.

I've talked to my immediate neighbors about my skywatching hobby and they've been helpful in turning off outdoor lights when they're not using them. I convinced the local park supervisor to turn off the playground lights at 10 pm.

Everybody who's interested in skywatching and astronomy should join the International Dark Sky Association.

[ta152h0]

if you work the words well, you may coinvince them to have a telescope night tailgate party with no lights the enrire block and have the kids ( all of us have the kids in us ) to come out and see jupiter while having a hot dog , just like campind. SWho knows, the great poohbah may even throw a large pebble overhead and give a show

[Anthony Barreiro]

if you work the words well, you may coinvince them to have a telescope night tailgate party with no lights the enrire block and have the kids ( all of us have the kids in us ) to come out and see jupiter while having a hot dog , just like campind. SWho knows, the great poohbah may even throw a large pebble overhead and give a show

That's a great idea, Wolf. Fortunately there's another park on a nearby hill that's above all the street lights and considerably darker. I often take a small telescope up there and accost unsuspecting passersby with views of the cosmos.

[ccheers]

I find it hard to believe wildfire as an explanation for the lights over Central Australia. When were the images taken? I know there were grassfires around Alice Springs this summer (our summer) but most of the area is desert with insufficient fuel to light up the night sky.

[Perk Cartel]

Thanks to all for the education regarding this image of the world at night tending to exaggerate the depiction of the intensity of constant global illumination. The almost comical interpretation by myself and others of the West Australian lights indicating invisible infrastruture and therefore querying the reliability of the data, when instead were depicting transient wild fires, fleeting in general time scales, suggests the same method applies to the rest of the image mapping, recording all transient nightime photopic events as apearing constant. A fascinating lesson in critical analysis well learned, many thanks again to all. The world just isn't any where near as bright on any one at night as the image suggests, and is as correctly described, an image compositally accumulated over time.