World Builders™                                                                  Session Three  --  Meteorology             

Temperature Comparisons on 
Venus, Earth, and Mars
    

The conditions on a planet's surface are affected by the planet's atmosphere and climates.


     Venus, Earth, and Mars travel in neighboring orbits around the sun. All of them are rocky planets, but only the earth has abundant life. Only the earth has conditions which support the presence of liquid water.

The surface temperatures of these planets are governed by two factors:

  • the amount of energy that they receive from the sun and
  • the composition of their atmospheres.

Venus

     Venus is closer to the sun than the earth is. It has a very thick, dense atmosphere, made up mostly of carbon dioxide. The carbon dioxide acts like a blanket and keeps the sun's heat  trapped on the suface of Venus. This is called the Greenhouse Effect.

     Scientists tell us that the temperature on Venus is about 890 degrees Fahrenheit. This is 477 degrees Centigrade (or Celsius). At this temperature lead and tin would be melted. Carbon-based life forms would be vaporized. Water would boil away.

It is difficult to discover what the surface of Venus is like. Our earth probes do not survive long in the heat, and the dense,cloud-filled atmosphere makes it difficult to transmit information and signals.

Earth

mountain meadow     Earth would be too cold for life if it had no atmosphere. The atmosphere holds enough of the sun's heat to make life possible here.

    Temperatures on earth range from a high of perhaps 130 degrees Fahrenheit to about -90 Fahrenheit. There are places on earth in which it is challenging for us to stay alive. There are living things in most earth environments, however.

      For purposes of comparison, let's say the temperature on earth in Los Angeles is about 70 degrees Fahrenheit, which is 21 degrees Centigrade. This is pleasant for carbon-based life forms, though some with adaptations for cold might feel uncomfortably warm.

 Mars

surface of Mars    Mars is the furthest rocky planet from the sun. It is a smaller planet than the earth, and has lost much of its atmosphere. The weaker gravity of Mars allows more atmospheric molecules to escape into space.

     As a result of Mars' very thin atmosphere, solar heat escapes easily. The temperature on Mars can be as high as 50 degrees Fahrenheit (10 C) at the equator and as low as -185 degrees Fahrenheit (-120 C) at the poles. Carbon-based life forms could survive at the warmer temperatures (given oxygen and other necessities) but the water in our cells freezes at 0 C, and maintaining our body heat would be challenging in even the warmest areas. We would have to really focus on staying warm at night and during the winters. For purposes of comparison let's pick -30 Centigrade (Celsius) for our temperature on Mars.

Now, let's look at the behavior of some of our familiar elements here and on nearby planets.

  • The melting point is the temperature at which a solid turns into a liquid.
  • When a substance reaches its boiling point it becomes a gas.
Element Melting Point C Boiling Point C State on Venus
at 477 C
State on Earth
at 21 C
State on Mars
at -30 C
water 0 C 100 C gas solid/liquid/gas solid ice
nitrogen -210C -196 C gas gas gas
sulfur 115 C 445 C solid/liquid/gas solid solid
lead 328 C 1750 C liquid metal solid solid
tin 232 C 2603 C liquid metal solid solid
silicon 1414 C 3267 C solid solid solid
gold 1064 C 2857 C solid solid solid
iron 1538 C 2862 C solid solid solid

As you can see, life as we know it thrives in a narrow temperature range. It is amazing to think that life has been here for billions of years -- and during all that time, there has been liquid water on earth every day.


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