The Four inner worlds!
The gap or scar on the Mercury Picture is from lack of data  when  this
old picture of Mercury was released.  Mars and Mercury are much smaller
than Earth and Venus.  Here the surface of Venus is shown with the Very
Thick  Clouds  removed revealing the desolate, dark, volcanic lava flow
surface.  The first few spacecraft sent to Venus  by  America  and  the
Soviet  Union  were  crushed  by  the atmospheric pressure or had their
electronics fried by the 900 degree F heat at the surface.  If  we  put
on  our  specially designed space suits and walked out onto the surface
of Venus we would find the dim sunlight filtering thru the  clouds  far
dimmer than we are used to on Earth during the day time.  The yellowish
tinge to the air around us from all the sulfur from  volcanic  activity
really adds an alien look to the terrain.

For more pictures of Venus click here Planet Venus
For NEW Mercury Pictures click here Mercury Messenger Spacecraft