Terrestrial Planets Cruise

Staring Mercury, Venus, and Mars

Distance from the Sun

  • 35.98 million mi - Mercury
  • 141.6 million mi - Mars
  • 67.24 million mi - Venus


  • Venus - Venus is the second planet from the Sun, and considered in many ways to be a twin planet of Earth. It has a similar size, mass, density and gravity, as well as a very similar chemical composition
  • Mercury - Mercury is the smallest planet in the Solar System by surface area, volume, and equatorial diameter. Surprisingly, it is also one of the most dense
  • Mars - Mars has a striking red appearance, and in its most favorable position for viewing, when it is opposite the sun, it is twice as bright as Sirius, the brightest star. Mars has a diameter of 4,200 mi (6,800 km), just over half the diameter of the earth, and its mass is only 11% of the earth's mass.


  • The atmosphere of Mars is less than 1% of Earth's, so it does not protect the planet from the Sun's radiation nor does it do much to retain heat at the surface. It consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and the remainder is trace amounts of oxygen, water vapor, and other gases
  • Mercury's atmosphere contains small amounts of hydrogen, helium, and oxygen. It also has even tinier amounts of sodium, potassium, calcium, and magnesium. Some of the gas particles come from the solar wind. Others are made by radioactive decay or when micrometeorites smash into the surface
  • The atmosphere of Venus is very thick and is about 90 times more massive than Earth's atmosphere. It is mostly carbon dioxide gas (about 96%), with some nitrogen (about 3%) and a very small amount of water vapor (0.003%). Venus also has a thick layer of sulfuric acid clouds


  • Venus means "love, sexual desire" in Latin. This was the name of the Roman goddess of love, equal to the Greek goddess Aphrodite
  • Mars is possibly related to Latin mas "male" (genitive maris). In Roman mythology Mars was the god of war, often equated with the Greek god Ares
  • The name Mercury is from the Latin Mercurius, probably derived from Latin mercari "to trade" or merces "wages". This was the name of the Roman god of trade, merchants, and travellers, later equated with the Greek god Hermes