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View Full Version : Pale blue dot: what causes the bands?


dotancohen
Oct15-09, 11:31 AM
In the famous photo "Pale Blue Dot" of the Earth from outside the solar system, one can see "bands" of colour around the Earth. What causes these bands? Is that an optical illusion? Does the band in which Earth is found describe the Earth's orbit? What are the other coloured bands? What gives them their colour? Here is the photo for reference:
http://upload.wikimedia.org/wikipedia/commons/7/73/Pale_Blue_Dot.png

Thanks in advance.

Hurkyl
Oct15-09, 11:57 AM
From NASA's page (http://visibleearth.nasa.gov/view_rec.php?id=599): (found in Wikipedia references)
Coincidentally, Earth lies right in the center of one of the scattered light rays resulting from taking the image so close to the sun.

dotancohen
Oct16-09, 04:59 PM
Thanks, Hurkyl! So the band is an artefact of the photograph and would not be seen by an observer at Voyager's location?

DavidFix
Nov13-09, 07:28 PM
Correct. You'd have a hard time looking that way without a filter, though... The sun would be very bright, and quite large. :)

A nice little comparison is here:
http://www.messenger-education.org/Interactives/ANIMATIONS/Planet_Size_Comparison/planet_size_comparison_full.htm

It's just glare, in other words. :)

dotancohen
Nov14-09, 09:35 AM
Thanks, Davidfix. That Messenger site is great!

DavidFix
Nov14-09, 06:42 PM
No problem. :) Yeah, that site has some cool stuff... Gives you a good idea of the relative size of the planets, for sure. :)

Damn, the sun is BIG! :D