QUESTION:
Where do you find mercury to put in thermometers? Does mercury have a
different reaction on Mars than on Earth?

ANSWER from Smart Filter on November 13, 1997:
According to the handbook of Chemistry and Physics, mercury freezes at -38.87
degrees Celsius.  That means that it would not be very useful on Mars,
since temperatures quite regularly get below that point. Pathfinder
measures temperature on Mars by thin wire thermocouples mounted on a
meteorological mast.  In other words, Pathfinder uses an electronic
"thermometer" rather than a traditional mercury or alcohol thermometer.

I assume your question about where they find the mercury to put into
thermometers refers to where mercury comes from.  Mercury is a naturally
occuring element.  It is found as a compound, mercury sulfide, in the rock
called cinnabar.