World-at-Night satellite cam

[reg373]

Hope it's ok to post this link I found, absolutely awesome satellite
view of the earth at night, in rotation;

www.Balkingpoints.com

-

[mike_c]

1. just looking at that awakened a serious nighttime desert jones....

There are still lots of places on the planet-- even in the tropics and temperate zones-- with little or no nighttime light pollution. High deserts are best, IMO.

[reg373]

2. deserts at night

Absolute best place to see the stars!

[MineralMan]

3. Deserts are great. But my favorite star-gazing place, ever,

was a little bowl with a small lake in it in the Sierra Nevada mountains. I had packed in alone, and it was way off-trail. It had a small population of planted golden trout, which I fished for during the day. That night, on the lake shore, I slept outside my tent, or was going to. Lying on my back, I watched a broad circle of sky, full of stars, for hours. It was incredibly dark and there was no moon, no clouds, and absolutely zero light polution at 11,000 feet.

One of my pinnacle experiences, to be sure.

[Vinnie From Indy]

5. I did a solo camp at the north rim of the Grand Canyon during the 1990s Hale-Bopp Comet

It was spectacular!!!

[tangent90]

4. It's an interesting image but it isn't a photograph...from a satellite or anywhere else.

:D

[Terran]

6. I was kinda wondering about that.

It shows the eastern half of the US looking like solid urban/suburban development, and that's just not true. Missouri, where I live, is mostly empty rural land and should appear dark except for a few blobs of light. Plus the "lights" are far too bright to be real...

[reg373]

7. enhanced image, probably

It looks like a cobbled together set of sattelite pics, then enhanced.
All of the civilized areas of the globe, seem to be accurate

[tangent90]

8. Well, I'm pretty sure nobody makes a lens that takes a Mercator Projection snapshot.

:D :rofl:

[Terran]

9. Oh yeah, good point!

:dunce:

[elleng]

11. PROLLY not!

.

[SmileyRose]

13. Plus it's not night on the whole planet at the same time.

[muriel_volestrangler]

10. Original is from NASA, explained here:

http://apod.nasa.gov/apod/ap001127.html

A composite from hundreds of pictures.

includes a link to a high res (400M!) version (they ask you to use BitTorrent to download it), if you want.

[Xithras]

14. Actually, it's not really even a composite photograph.

The generic Earth photograph is a composite of thousands of photographs similar to those used on Google Maps or Google Earth. The photos were normalized to make them look consistent, and then tinted to make it look like a "night" shot.

The actual light dots weren't taken as photos, or in those satellite images. The DMSP satellites have sensors that detect and log light sources on the ground. A number of years ago, someone at NASA took the DMSP light source data, fed it into a computer, and generated a "map" of all the detected sources of light emissions on the surface. This "map" was overlaid on the composite satellite image mentioned above to create the "Earth At Night" shot.

One big thing to keep in mind is that the light sources are NOT proportional to actual intensity. A 10 watt bulb in a dark desert was rendered in the map with the same relative intensity as a 5000 watt floodlight in downtown L.A. Infrared light emissions were also detected and included, and the vast majority were rendered with higher intensity levels than the original emissions source had.

The real Earth at night isn't nearly as bright as that photo would lead you to believe. The lights of the big cities are easily visible from space, but aside from Chicago, St. Louis, and a few other large cities, the midwest looks extremely dark from orbit. In fact, most of the world looks extremely dark from orbit...only major urban areas and a handful of extremely bright emissions sources are actually visible from space using the naked eye. Smaller towns are only visible as dull glows, and only if you're looking for them.

[muriel_volestrangler]

15. Interesting - thanks

I was surprised that you'd see some lights in the Sahara, while large parts of the more heavily populated parts of Africa, like Congo, were just about as sparse. The 'not proportional to intensity' might explain that.

[reg373]

16. lost in the desert...

Perhaps they only use 40 watt bulbs in the Congo... ;^)

[SmileyRose]

12. You might enjoy this link better.

http://www.fourmilab.ch/cgi-bin/Earth?imgsize=320&opt=-l&lat=48.9167&ns=North&lon=2.91667&ew=West&alt=957&img=learth.evif

[and-justice-for-all]

17. The planet looks like it has a disease..nt

[reg373]

18. well...

if the sun really went out, that would be the mother of all diseases... ;^)