Re: CO2 and the martian
No, 99% of spiders are raised above the ground not depression. The sun in E1201762 is coming from 159 degrees clockwise from straight up.
We researched this quite thoroughly for out paper. Each image has these details at MSSS, there's no way to mistake it.
Sun azimuth: 68.89
and add 90 degrees.
http://barsoom.msss.com/moc_gallery/e07_e12/images/E12/E1201762.html
