Strange Earth Science PoD

The cosmos at our fingertips.
User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1448
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Strange Earth Science PoD

Post by JohnD » Mon Oct 03, 2011 8:59 pm

The EarthPoD for toady 3rd Oct 2011 shows a green flash.
But the cloud scape around the Sun is strange, making it look as if the Sun is popping up through the clouds.

http://epod.usra.edu/blog/

Explanations for this illusion?

JOhn

User avatar
geckzilla
Ocular Digitator
Posts: 9158
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: Strange Earth Science PoD

Post by geckzilla » Tue Oct 04, 2011 5:04 am

The atmosphere grows thicker and thicker toward the bottom of the sun until the light is dimmed enough that it can no longer penetrate the clouds. The gradient from thinner at the top to thicker at the bottom creates the illusion. /layman's understanding
Just call me "geck" because "zilla" is like a last name.

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1448
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: Strange Earth Science PoD

Post by JohnD » Tue Oct 04, 2011 6:27 am

Thanks, geckzilla, but if I may explain the appearance that puzzles me?

There is a clear line of cloud that delimits the lower visible edge of the Sun. But the horizon is, apparnetly, also a line of cloud, and that is higher up the Sun, making it appear that the Sun is in front of the horizon!. The hulking mass of cloud to the right also appear to be further away than the sun, perhpas because dark objects always recede.

ThIs is clearly an aillusion, but a remarkable one. Any one else see it?
John

User avatar
geckzilla
Ocular Digitator
Posts: 9158
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: Strange Earth Science PoD

Post by geckzilla » Wed Oct 05, 2011 3:35 am

Oh, I definitely see what you mean. Once, there was an APOD with a similar illusion which showed the moon and also Jupiter and its moons... All behind clouds. Check it out: http://apod.nasa.gov/apod/image/0907/lu ... 4_riou.jpg

Somehow that photo still baffles me.
Just call me "geck" because "zilla" is like a last name.