Earth at night

Check out the cool picture of Earth at night.

Link.

(Click on the picture for a full size image).

I have seen that before... Its pretty kewl and amazing. I wonder how long it took to make that picture as well. Not everyday is the whole earth cloudless/ubbthreads/images/graemlins/wink.gif. It must have really taken weeks for the satellites that did that to go around the earth countless amount of times and finally get pictures of a single area without clouds. Kewl Stuff...
Cameron

And those are just the CPF members!

I'm surprised that there are lights visible in northern Alaska and even in southwest Greenland.

I'm surprised at how little of our planet is "unlit", so to speak.

The lghts in northern Alaska are Point Barrow and Prudhoe Bay. More interesting is the contrast between North and South Korea...

That is a great picture. I've had the image for about 2 years and it gets set as my wallpaper on a rotating basis.

In addition to the contrast between North and South Korea, Afganistan and Pakistan are also very dark compared to their neighbors. Notice also the Carribean sea - Puerto Rico (most affluent island) is almost glaring bright and Haiti (arguably the poorest nation in the region) on the western half of Hispanola almost is not visible. The Dominican Republic on the eastern half is much more developed. Also compare Mexico to Canada. I just can study this image all day long.

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Lurker said:
And those are just the CPF members!

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We can recognize Mr Bulk in the middle of the Pacific very easily /ubbthreads/images/graemlins/grin.gif

wow, it looks like up here in Northern Maine is the least lit place on the East Coast, haha.

Goes up to a 6 A4 sheet print quite nicely, thank goodness for compatible ink, Pacific is big and black, and special offer photo paper ;-)

Adam

I've had this on my desk top for the past half year. It's probably easy on the CRT with a mostly dark screen.

I'm assuming the image isn't in true color, or perhaps the response of the cameras saturates past a certain light level. Most of the artificially illuminated areas appear pure white rather than the yellowish color of HPS or LPS street lights. I'm also surprised at how many dark areas there are. It looks like most of the world's 6+ billion people are concentrated in less than 20% of the available land.

As an amateur astronomer and someone who enjoys the simple pleasure of a sky full of stars, this image always makes me sad. It is a good indicator of just how out of control light pollution has gotten. Light pollution robs us of our view of the stars in the night sky. Also makes our flashlights look much less impressive because it is so darned bright outside at night. In fact, if you really want to be impressed by your greenie, try it out a couple hundred miles away from the nearest city. Even an unmodded 5mw unit looks really impressive.

Begin soapbox mode...

What you see in the picture represents a tremendous waste of light and energy because you are seeing light that is simply going up into space and not serving any useful purpose (other than to make cool satellite images). This is primarily the result of crappy lighting fixture designs that spew light out in all directions. The ironic thing about all this is that the lighting is actually less effective (less safe) because the user has a direct line of site with the light source. Imagine how ineffective and annoying our flashlights would be if the light source were not hidden behind a housing and reflector. Kind of like trying to walk around in the woods at night using a bare Side Emitter LS as your light source. When possible, light should always be directed only towards the area it is intended to illuminate and nowhere else.

Fortunately, newer streetlight fixtures that prevent light from going upwards (full cutoff housings) are being developed and implemented. I find it much easier to see the areas these lights are intended to illuminate because I am not distracted by the direct glare of the light source. Many communities have started using these new fixtures with great results. You can even use a lower wattage bulb because the light is being focused only where it is needed.

Some of the results of improper lighting techniques:
- less effective lighting
- wasted energy and higher municipal electric bills (wasted tax dollars)
- light trespass (lots of unwanted light coming into our homes at night)
- fewer stars visible in the sky at night
- less fun with our Flashaholic toys

For more info about this subject, check out this site: web page

End soapbox mode...

Sorry Photon, I did not intend to hijack your thread, but every time I see folks discussing this image I feel compelled to discuss what it truly represents.

look in ga ya will see me and mt vip

Right near my window are some milky glass globes with HPS (high pressure sodium) bulbs in them. They generate light down, sideways, and up, with pretty much equal intensity at all axes.
How wasteful. /ubbthreads/images/graemlins/frown.gif /ubbthreads/images/graemlins/jpshakehead.gif /ubbthreads/images/graemlins/frown.gif

Well, I agree with Craig that Non-cutoff fixtures (like the round globes)are pretty wasteful. Most of the light just heads up for the sky.

Hey, I remember that I used to be a streetlight nut myself a while back until streetlights.net "ran out of business"
so I guess I might be getting back into my streetlight intrest

Anyway, back to my topic; here in my neighborhood, we have both semi-cutoff and full cutoff fixtures. The semi-cutoff fixtures do create some glare but there are not many streetlights in my neighborhood.(In fact, I can acutally see stars leaning out my window). There are quite a few full-cutoff fixtures appearing here and there where I live and new neighborhoods are useing full-cutoff fixtures. Most of the streetlights in Chino Hills are full-cutoff as well.

Yes, I do know that few people in large cities get even get to see stars because of the light pollution. I still remember the blackout in the Eastern US last August and read that one woman saw the Big Dipper for the first time during the outtage.

Most cities are starting to switch to full-cutoff fixture (mine already has them) so it may be possible to see the stars again. (About my own experience-I can look straight up and see stars at night but if I look south-west the "sky-glow" over Orange County is very pronounced (dark sky and then light) and I can also look North-East and see the sky glow above San Bernardino and Ontario as well.

Couple sites I know:
Streetlight Optics

Los Angeles from Mt Wilson-1908

LA from Mt Wilson-Present

Look at how much the city has grown

Found this picture as well from http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=14772



Look at where I live!