Mars images: NASA/JPL/Cornell University/University of Arizona. Earth images: Bill Dunford.
Can you tell which is Earth and which is Mars? On the left, images from the Red Planet as captured by the Opportunity rover and the Mars Reconnaissance Orbiter. On the right, locations of roughly the same scale in and around Canyonlands National Park, Utah. Click the image for a longer caption and more details.
From top to bottom:
On the left, the edge of Victoria Crater on Mars as seen by the robotic geologist Opportunity. On the right, an overlook of Shafer Canyon at Utah's Dead Horse Point, near Canyonlands National Park.
An orbital view into Mars' Becquerel Crater. On the right, Shafer Canyon again.
Layers of sandstone in Victoria Crater. Layers at the side of the “Park Avenue” trail in Arches National Park, Utah. (Both images in natural color.)
Another section of the wall in Victoria Crater. Sandstone layers found in the backcountry of Canyonlands National Park.
A Martian mesa seen from orbit by the Mars Reconnaissance Orbiter. Another view looking down from Dead Horse Point.