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EarthWolf

Member

From: Missouri, U.S.A.

Registered: 2004-07-20

Posts: 59

Re: Gyrs and Kelvin, What Are They?

Hello,

I've been reading some interesting papers by NASA on terraforming and exobiology and I've come across some terms I'm unfamiliar with. Gyrs are apparently a measure of time in geological terms, perhaps a Gyr is one billion years each. ( A Gigayear? ) I pretty much understand that Kelvin is a measure of temperature, though I don't know the conversions into Celsius or Fahrenheit. Does anyone know about these things?

I would really appreciate the help, thanks.

Cordially,

EarthWolf

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" Man will not always stay on the Earth. "

Konstantin Tsiolkovsky

Shaun Barrett

Member

From: Cairns, Queensland, Australia

Registered: 2001-12-28

Posts: 2,843

Re: Gyrs and Kelvin, What Are They?

Hi EarthWolf!
    Yes, I believe a Gyr is a billion years.   

    The Celsius scale of temperature, as you probably know already, runs from zero degrees at the melting point of water up to 100 degrees at the boiling point of water, 0 deg.C to 100 deg.C.

    It was found that there is a lower limit to the temperature of a substance. At -273 deg.C, all atomic and molecular movement ceases (apart from some quantum fluctuations); in other words, you can't extract any more energy from the substance and make it colder.
    This is the famous 'Absolute Zero' we've all heard about.

    Somebody (it might have been Lord Kelvin, I can't remember) decided that, for scientific purposes, an absolute scale of temperature was necessary. They set the lower end of the scale at Absolute Zero but used the same degrees as are used in the Celsius scale, and called the scale the Kelvin scale.
    Thus, Absolute Zero became 0 deg.K, with the melting point of water occurring at 273 deg.K, and the boiling point of water at 373 deg.K.
    (Incidentally, you'll notice that there are no 'minus' temperatures in the Kelvin scale.)

    So, if you want to convert Celsius to Kelvin, just add 273 degrees.
    For example, the surface temperature of Titan is about -180 deg.C. Adding 273 degrees gives us the temperature in  degrees Kelvin, i.e 93 deg.K

    It's harder to convert degrees Kelvin into degrees Fahrenheit because a degree in one scale is not the same magnitude as a degree in the other.
    What I do is just use the conversion equation to convert Fahrenheit to Celsius, and then add 273. 

[In case you're unfamiliar with the conversion of Fahrenheit to Celsius:-
  Take the temperature in Fahrenheit, subtract 32, and multiply by 5/9.
   e.g. 50 deg.F - 32 = 18
                18 x 5/9 = 10 deg.C

   In reverse, take the temperature in Celsius, multiply by 9/5, and add 32.
   e.g. 20 deg.C x 9/5 = 36
                       + 32 = 68 deg.F ]

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