Features:
- Original caption:
"Global mosaic
made from 102 Viking 1 Orbiter
images of Mars, taken on orbit 1,334,
1980 Feb22.
The images are projected into point perspective, representing what a viewer would see
from a spacecraft
at a vertical altitude
of 2,500 km.
At the center is the huge canyon
Valles Marineris.
Note the channels running up (north) from the central
and eastern portions of Valles Marineris
to the area at upper right,
Chryse Planitia.
At the left is the Tharsis Montes
(3 giant shield volcanoes
of the Tharsis region: the southernmost one is
hard to see),
and to the south is ancient, heavily impacted terrain.
Viking 1 Orbiter image MG07S078-334SP."
(Slightly edited.)
- Valles Marineris is the largest
canyon (or
more accurately system of canyons) on
Mars by far.
It extends over 4000 km (almost a quarter way
around the equatorial region), reaches to about 7 km deep, and is up to
200 km wide
(see Wikipedia: Valles Marineris).
It is considered to be a
rift valley system.
- Some impact craters,
channels (probably mainly
Martian outflow channels), and
Martian dark regions
can also be seen.
The Martian dark regions
are regions of exposed volcanic
basalt.
The regions are exposed in being
NOT heavily covered by
Martian dust
(see Wikipedia: Syrtis Major Planum)
which is reddish due to
iron oxide mineral content
i.e., rust).
The old rusty dust of Mars.