Mercury & Venus

							Mercury & Venus
          Orbital Properties
Physical Properties & Surface Features
 Compare & Contrasting the Planets
        Mercury & Venus Cont’
   The Origin of the Mercury & Venus
   Evolutionary History of Mercury and Venus
   Distinctive Features of both planets
   How each planet effects the other.
   Mercury is the1st planet in the solar system. It has no
    atmosphere and has the most extreme temperatures in
    the solar system for day and night. Mercury is heavily
    cratered.
 Mercury is less heavily cratered than the Moon



Some distinctive
features:
Scarp (cliff), several
hundred km long and up
to 3 km high
Caloris Basin, very large impact feature; weird
terrain on opposite side of planet:
Mercury is much denser than the Moon, and has a
weak magnetic field – not well understood!
Mercury much less well understood
• Formed about 4.6 billion years ago
• Melted due to bombardment, cooled slowly
• Shrank, crumpling crust

Mercury has no maria, but does have extensive intercrater plains and scarps
 All we know about Mercury has come from the three
Flybys From Mariner 10. Mercury's magnetic field
Comparisons to the Earth’s magnetic field is
it is 1/100th as strong as ours, but does deflect the
Solar wind to some degree. The only polar regions that
Mercury has are believed to be deep craters on its surface
with ice at their depths.The craters are also very dark.
The orbit of Mercury is more elliptical than that of any other
terrestrial planet. Mariner 10 took its pictures in 1974.
Mercury has the highest eccentric orbit of the terrestrials.
  Two Mercury years are the same length as three Mercury
sidereal days.
 Ice has been detected near the poles of Mercury.
Mercury has a strange spin due to the suns pull
Venus
Orbital Properties
Physical Properties
Long-Distance Observations of Venus
     Synodic Periods and Solar Days

The Surface of Venus
The Atmosphere of Venus
Venus’s Magnetic Field and Internal
Structure
• Venus is much brighter than Mercury, and is
farther from the Sun and closer to Earth.
• Called morning or evening star, as it is still
“tied” to Sun.
• Brightest object in the sky, after Sun and
Moon.
Rotation period: 243 days, retrograde
Dense atmosphere and
thick clouds make
surface impossible to
see
Surface temperature is
about 730 K – hotter
than Mercury! These are
long distance
observations
The Surface of Venus
The Surface of Venus
           Volcanoes on Venus
 Above Sif Mons
  Largest volcanic mountain range is Maxwell
  Mons
 Below Gula Mons

 The largest active land features on Venus.

 Both volcanoes are believed to have had

 recent bouts of activity.

 This activity has added to the atmospheric problems.
         The Surface of Venus
Venus’s largest impact
  crater, named after
  Margaret Mead:
  The Surface of Venus
From the Venera Landers
        The Atmosphere of Venus
Venus’s atmosphere is very dense
Solid cloud bank 50–70 km above
surface
Atmosphere is mostly carbon
dioxide; clouds are sulfuric acid
        The Atmosphere of Venus
   Venus is the victim of a runaway greenhouse
    effect – just kept getting hotter and hotter as
    infrared radiation was reabsorbed.
Venus’s Magnetic Field and Internal
            Structure
   No magnetic field, probably because rotation
    is so slow
   No measurements available that would give
    clues to internal structure
   Venus has a day longer than its year.
          Summary of Chapter
• Venus is never too far from Sun, and is the
  brightest object in the sky (after the Sun and
  Moon)
• Atmosphere very dense, mostly carbon
  dioxide
• Surface hidden by cloud cover
 Surface temperature 730 K

 Rotation slow and retrograde
   Many lava domes and shield volcanoes
    Venus is comparable to Earth in mass and radius
    Large amount of carbon dioxide in atmosphere,
    and closeness to Sun, led to runaway greenhouse
    effect and very hot surface
   Earth and Venus are often called sister planets; in
    which ways are they most alike because of
   size, density, and surface gravity
   Venus orbits the Sun in 225 days and 243 on its
   own axis. Pioneer is the Venus Orbiter from NASA.
    Our best data as of late has come from?
   Magellan radar data and observations from Earth.
A surprise from the Pioneer Venus photos was that the
clouds rotate around the planet in only four days, very
unlike the slow surface rotation
The orbiter that gave us the most detailed maps of Venus to
date was Magellan.
Venus has a feature named Aphrodite Terra it is a continent
sized plateau and . Maxwell Mons on Venus is a huge shield
volcano. The percentage of the surface of Venus could be
characterized as continental sized highlands? less than 10%
    Most of the craters on the surface of Venus are from
   Volcanoes. The largest volcanic structures on Venus are
 coronae. The only spacecraft to land on Venus were
Veneras from Russia. Why will it be hard to determine the
nature of Venus' interior? Because No seismograph can last
long enough at Venus' temperatures to pick up quakes.
The Greenhouse effect has on the surface environment of
What is the main constituent of the atmosphere of Venus? Carbon
Dioxide.
The composition of the clouds of Venus is sulfur and sulfuric acid
droplets.
 If Venus once had an ocean, where did it go? The water broke
into hydrogen, which escaped to space, and oxygen, which became
trapped in the planet's surface rocks.
 The absence of a magnetic field on Venus probably stems from its
  slow rotation.
 The following contributes to Venus being so hot? It is closer than
Earth to the Sun, Its atmosphere is much denser than the Earth's,
Its atmosphere is made chiefly of carbon dioxide, and It has very
little axial tilt so the equator is always directly exposed to the Sun
 a volcanic crater sitting atop a huge shield volcano is Caldera
the composition of the clouds of Venus is Sulfuric Acid
Ishtar and Aphrodite Terra are continents on the surface of Venus
The best radar data about the surface of Venus came from the Magellan orbiter