Transcript Earth, Venus, Mars

Earth versus Mars:
The two planets have striking similarities. They have …
 roughly the same amount of land surface area;
 relatively similar atmospheric chemistry; and
 large, sustained polar caps comprising water ice;
and show
 similar tilts in
their rotational
axes that give
them strong
seasonal
variability; and
 historic evidence
of changes in
climate.
In this animation, we see both planets
in true color first, then draped in false
color, showing relative altitudes of surface features. Blues indicates
low features; reds and whites indicate high features.
http://svs.gsfc.nasa.gov/stories/mars_earth_20040421/images/item02.mpg
Indeed, Earth’s dry valleys do look similar to those on Mars. For instance,
in this animation, we plunge from space down to a remarkable scene in
Antarctica, the Don Juan Pond, one of the saltiest, coldest bodies of water
on Earth. In the first scene the camera slides down the valley slope and
stops above the actual pond of sub-freezing water at the base. We see the
crinkled folds and
dug out rivulets
and gullies eroded
into the landscape.
They serve as the
signs of surface
erosion and are
analogous to the
kinds of tell-tale
signatures that
Mars experts want
to study more
thoroughly for the
signs of a wetter
Martian past.
http://svs.gsfc.nasa.gov/stories/mars_earth_20040421/images/item04b.mpg
Evidence of Surface Water: Earth Deltas, Martian Deltas
These images compares how evidence of water appears on Earth,
offering clues as to where we might look for itspresence on Mars.
 The first two sequences here depict (a) the mouth of the Colorado
River in the Mexican Baja, and (b) the Lena River Delta in Russia. Data
for these scenes come from the Landsat 7 spacecraft.
 As for Mars, we see here
the so-called “Distributary
Fan” located northeast of
Holden Crater. As seen
from Martian orbit by the
Mars Orbiting Camera
flying on the Mars Global
Surveyor spacecraft, this
dramatic visualization
shows us where liquid
water likely flowed across
the Martian surface
sometime in the planet’s
past.
http://svs.gsfc.nasa.gov/stories/mars_earth_20040421/images/item06.mpg
The Earth bursts with life, with carbon as life’s proxy, because life as we
know it basically implies transactions in carbohydrates (CH2O). A thorough
understanding of the Earth’s carbon cycle is therefore vital to a search for
life elsewhere in the universe. The undulating colors in these scenes come
from NASA’s SeaWiFS instrument. They show the cycle of life as it ebbs
and flows through the carbon cycle. The pulse of this carbon uptake is
reflected in the oscillation of chlorophyll concentrations, depicted by this
intuitive false color representation.
On Mars, scientists are
looking for signs of life in
the planet’s past. Unlike the
Earth, Mars is no longer a
hospitable place for life,
because it is generally
bathed in a lethal dose of
cosmic radiation, not to
mention high energy the
particles blown by solar
wind. It is also cold and dry,
with no ready availability of
water. http://svs.gsfc.nasa.gov/stories/mars_earth_20040421/images/ElanVital.mpg
Magnetic Signatures:
Mars does not have the same kind of magnetic field as Earth. But
evidence collected by the Mars Global Surveyor (MGS) indicates that
the planet may have once had a global magnetic field, generated by
an internal dynamo.
Evidence suggests
that the planet’s
magnetic field
reversed direction,
or flipped, several
times in its early
days as conditions in
the mantle and core
of the planet
changed. But that
dynamo faded,
leaving only faint
traces of its
magnetic past locked
in the Martian crust.
http://svs.gsfc.nasa.gov/stories/mars_earth_20040421/images/MagSignitures.mpg
Some Basic Facts about
Mars
Ave. Solar Distance:
227,940,000 km (1.52 AU)
 Diameter: 6,794 km
Rotational Period (one day):
24.622 hours
•
•
• Mean Surface Temp: -63_ C
• Orbital Period (one year):
686.98 days
• Moons: 2 (Phobos and
Demios)
• Gravity: 38% Earth
Some Basic Facts about Earth
• Ave. Solar Distance: 149,600,000
km (1AU)
• Diameter: 12756.34 km
• Rotational Period (one day): 23
hours, 57 minutes
• Mean Surface Temp: 14_ C
• Orbital Period (one year): 365.242
Earth days
• Moons: 1 (Luna)
• Gravity: 9.78 (m/s2) Earth