MARS
Viewed from Earth, Mars has a reddish color, and so was named after the Roman God of War. Its distance from the sun is about 1.5 times that of Earth. Its axis of tilt is 24 degrees. It rotates once every 24.5 hours, and its period of revolution is 687 days (about 23 months). It has two very small satellites Phobos (fear) which is 32 km in diameter, and circles Mars in 7 hours and 39 minutes and Deimos (panic) which is 16 km in diameter, whose period of revolution is 30 hours and 18 minutes.
For more dimensions: Mars dimensions
The mass of Mars is about one tenth the mass of Earth. It has a lower density (3.9 g/cm3) compared to Earth's 5.5g/cm3). So Mars probably does not an iron core at its center. Its internal composition is believed to be rocky and metallic with an extremely weak magnetic field (less than 0.004 times that of Earth) The surface temperatures range from 130 K (-143 C) at the South Polar Cap to 290 K (17 C) at the equatorial regions. The surface also has many impact craters. Mars also has polar caps and at least 12 extinct volcanoes, the largest Olympus Mons (Mount Olympus) is three times the size of Earth's largest volcano, Mauna Loa. Another interesting feature is the large canyon Valles Marineris four times as deep as the Grand Canyon and having the same length and width.
There was probably water on the surface of Mars, but the low atmospheric pressure precludes any now, although traces have been found in the atmosphere. It is also possible that life existed about 3.6 Billion years ago.
For more information including evidence of water on Mars, click below
How do people look for water on Mars? Click here for answers. Looking for water on Mars
For information on the rocks found on Mars, click here. Mars Rocks!
For Pictures of Mars Click Below
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Pictures of Mars
For details of Mars click below
Details
of Mars
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Mars pictures reveal frozen sea |
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A
huge, frozen sea lies just below the surface of Mars, a team of European
scientists has announced. Their assessment is based on pictures of
the planet's near-equatorial Elysium region that show plated and rutted
features across an area 800 by 900km. The team think a catastrophic event flooded
the landscape five million years ago and then froze out. They tell a forthcoming edition of Nature magazine
that sediments covered the ice, locking it in place. Large reserves of water-ice are known to be
held at the poles on Mars but if this discovery is confirmed by follow-up
observations, it would be a first for a region at such a low latitude. Dust covering "It's been predicted for a long time
that you should find water close to the surface of Mars near the
equator," Jan-Peter Muller, from University College London, UK, said.
"This is an area where
there are a lot of river features but no-one has ever seen a sea before, and
certainly no-one has ever seen pack ice before," he told the BBC News
website. The interpretation is based on images taken
by the High Resolution Stereo Camera on Europe's Mars Express spacecraft.
These show extensive fields of large, platy features - reminiscent of the
fractured ice floes found in polar regions on Earth. Finding exposed ice at the equator would be
unlikely. Very low pressures on the planet would lead to sublimation - the
ice would erode over time straight to water vapour. But the research group, led by John Murray,
from the Open University, UK, tells Nature that a crust of dust and volcanic
ash, perhaps just a few centimetres thick, has prevented this happening. "The story runs that water flowed in
some kind of massive catastrophic event; pack ice formed on top of that water
and broke up, and then the whole thing froze rigid," explains Professor
Muller. "Large amounts of dust then fell over
that area. The dust fell through the water and on top of the pack ice, which
explains why the pack ice is a different hue to the area around it." Feeder channels The water that formed the sea in the
southern Elysium, five degree north of the equator, appears to have
originated beneath the surface of Mars, erupting from a series of fractures
known as the Cerberus Fossae. Many of the features seen by Mars Express
have also been pictured by the Mars Orbiter Camera on the US Mars Global
Surveyor probe.
Further data is now required
to support the initial observations but already other scientists think the
interpretation is reasonable. "I think it's fairly plausible,"
commented Michael Carr, an expert on Martian water at the US Geological
Survey in Menlo Park, California, who was not part of the team. He told New Scientist magazine that a past
water source north of the Elysium plates had previously been suspected. "We know where the water came from...
You can trace the valleys carved by water down to this area." Mars Express has now been in orbit around
the Red Planet for a year. It has already confirmed US observations
that substantial water-ice lies at the poles, on its own and mixed with
carbon dioxide ice and dirt. Lander target The probe will soon deploy its Marsis (Mars
Advance Radar for Subsurface and Ionospheric Sounding) instrument, which has
been designed to find the planet's subterranean permafrost. This underground ice is thought to be the
major reservoir for water on Mars today. However, the way the instrument is set up
means it may not be able to see the Elysium sea because it is simply too near
the surface. Only if the ice mass extends down many tens of metres will it be
able to detect the sea-bottom boundary. The presence of so much recent (in the
geological timeframe) liquid water will excite the speculation that life
could have thrived in this area. "The fact that there have been warm
and wet places beneath the surface of Mars since before life began on Earth,
and that some are probably still there, means that there is a possibility
that primitive micro-organisms survive on Mars today," Professor Murray
said. "This mission has changed many of my
long-held opinions about Mars - we now have to go there and check it
out." Professor Muller added: "What we'd
like is for the European Space Agency (Esa), with UK support, to send its
next lander there." Details of the frozen sea were given at the
Mars Express science conference, taking place at Esa's European Space
Research and Technology Centre (ESTEC), in Noordwijk, the Netherlands.
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What
we'd like is for the European Space Agency (Esa), with UK support, to send
its next lander there 
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