A. The Parent Star
B. The Exoplanet
As a reasonable first approximation, the surface temperature of a planet can be related to how far the planet is from the parent star and how large and how hot the parent star is. To begin, the surface temperature and radius of each spectral type of star, as determined by astronomers, is presented below.
Locate the necessary information for this exoplanet and its star from the table above. Then enter the appropriate values in the form below. Remember that the formula is:
|Tp = (Rstar / 2 apl)1/2 Tstar|
Notes on Temperature Scales
There are three primary temperature scales used throughout the world in science, commerce and everyday life.
Notes on Habitable Planets and Temperature
Several factors determine the surface temperature of a planet:
If one assumes that the exoplanet has a significant atmosphere (a necessity for a habitable planet) and is a perfect absorber and radiator (that is, albedo and emissivity effects are ignored), then the average temperature of the surface of the exoplanet, in Kelvin degrees, can be estimated by the formula used above.
For a planet to be habitable for life as we know it, its surface temperature must be restricted to a fairly narrow range. Since water is one primary necessity, the planet's temperature must be considerably less than the boiling point of water and generally higher than its freezing point. (We can survive at temperatures less than the freezing point of water for periods of time, but our food supply from plants depends upon temperatures well above the freezing point of water.
Thus the broadest temperature range for life is between 0oC (32oF) and 100oC (212oF). This translates to 273 K and 373 K. (These temperatures are for one atmosphere of pressure. If the pressure is less or more than this, then these temperatures will be somewhat lower or higher than those given here.)
Simulation Authors: Richard L. Bowman (Bridgewater College) and David Koch (Kepler Mission)
Maintained by: Richard L. Bowman email@example.com (2002-04; last updated: 19-Apr-04)