Mars, the Red Planet is aptly named as it is a cold desert world covered in red-brown rust-coloured sands rich in
oxidised iron. In short, loosely speaking, Mars is covered with powdered rust. Its red colour led to its mythical
association with the Roman god of war, Mars.
Planet type: terrestrial, cold desert planet.
Equatorial Diameter: 6795 km.
Mass: 0.107 Earth masses.
Surface gravity: 0.376 g.
Orbit: Mars orbits Sol at 1.38-1.67 astronomical units with a year lasting 686.98 Earth days and a day length of 24
hours and 37.4 minutes.
Atmosphere: Thin, low pressure (about 0.007 times the pressure of Earth's atmosphere). An ionosphere is present
at 100-300 km. Mars has a diverse cloud system.
Surface Temperature: night-time temperatures: -140 degrees C, daytime temperatures rarely rise above zero
degrees C, though may reach 20 C in summer.
Magnetic Field: weak (about 0.2% of the Earth's), Mars has no radiation belts.
Life: none as yet discovered. Although the surface is too dry and blasted by ultraviolet rays, there may be liquid
water and life beneath the planet's surface.
Some key tourist attractions:
Active sand dune-fields are abundant on Mars, for example those that surround the North polar cap, and visible in
the images above as dark regions around the cap. These dunes are taller relative to the distance between
successive dunes than on Earth. Ripples six metres tall have also been observed.
A dust devil is a desert whirlwind that carries dust and is accompanied by strong electric fields. Mars has much
larger dust devils than those found on Earth - Martian dust devils may be several kilometres across and may reach
the size of Mount Everest! This compares to those on Earth which are typically about 10 metres across and 100-200
metres tall. Martian dust devils are also extremely common and criss-cross the planet's deserts on a daily basis.
Click on the imageabove to see the position of
the Valles Marineris canyon system (outlined).
Olympus Mons Volcano
The largest volcano on Mars, Olympus Mons is more than 600 km wide at its base and terminates in a 90 km
caldera at an altitude of 26 km. This dwarfs Earth's largest volcano, Mauna Kea, Hawaii, which is 120 km wide at its
base and 9.3 km high.
Global Dust Storms
Not only are dust devils enormous and frequent on Mars, but dust storms are also much more vast - in fact they are
frequently global and shroud the whole planet in dust for about a month at a time. These vast storms only require a
single day to develop. Dust particles have reached recorded speeds of 100-160 kilometres per hour (60-100 miles
per hour) in such storms. It is hard to explain all this aluvial activity on a planet that has a thin atmosphere, but the
dust may be very fine and it is hypothesised that it may also be driven into the planet's atmosphere by a build up of
electric charge, since Mars has no thunderclouds to dissipate excess charge electricity must dissipate in other ways.
Debate continues as to what drives dust devils and dust storms - the wind or the electric charge, or both.
Carbon Dioxide Geysers
The ice caps of Mars contain both water ice and frozen carbon dioxide. In summer the carbon dioxide ice thaws and
in winter frost deposits more frozen carbon dioxide. Recrystallisation of this deposited carbon dioxide is thought to
sort the particles, causing dust trapped in the ice to slowly sink downwards, leaving a top layer of clear ice about
one metre deep. This is thought to act like a lens, magnifying the Sun's light and heating the underlying soil. This
causes carbon dioxide gas to build up beneath the ice layer. Eventually this gas escapes through vents in the ice as
geysers that jet hundreds of metres into the atmosphere. Heavier darker material gets blasted out with the gas and
this material falls back down and deposits to form a cone around each vent with dark downwind streaks. The gas
tends to escape through the same vent sites each summer, and beneath the ice river-like channels are excavated in
the soil by the gas, forming a spider web of channels that radiate toward each vent.
Valles Marineris Canyon System
This vast equatorial canyon system measures 4500 km from east to west and 150 to 700 km from north to south.
Individual canyons may be up to 200 km wide and 7 km deep. This makes Earth's Grand Canyon look tiny (at 28 km
maximum width and 2 km depth).
|Above: A Martian Dust Devil - Click image to enlarge
|Star System Sol - Planet Mars: The Red Planet
North polar view.
South polar view
All planet graphics were rendered in Pov-Ray using image maps of Mars provided courtesy of NASA JPL.
Above: Mars modelled in Pov-Ray using an image map courtesy of NASA.
Above and below: a simulated Mars scape, modelled in Pov-Ray. This view is of a crater rim from a crater floor.
4th sept 2015
5th Sept 2015
Dry River Beds
Mars apparently once had plenty of liquid water running freely over its surface, since many dried-up river channels
still meander across its surface and sedimentary rocks that formed in water are to be found. Recently new streams
of liquid, probably water, have been discovered that flow momentarily across the surface of Mars after springing
forth from slopes (crater rims, hills etc.). This adds weight to the hypothesis that Mars contains a subsurface
reservoir of liquid water. It is already known that layers of water ice exist beneath the Martian surface, but evidence
suggests that further down there may be liquid water. Also, methane has been detected in the Martian atmosphere,
which presumably came from beneath the planet's surface by some out-gassing process. This methane could be of
geochemical or biological origin. It is looking as if conditions on Mars are suitable for several forms of life on Earth,
but whether or not life has actually evolved or currently exists on Mars is still unknown.
Equatorial View: mars is tilted on its axis by 25.19 degrees.
North Polar View