I have read several methods for calculating the habitable zones of exoplanets, but every single one of them includes assumptions about the planet that are yet unknown. Such as whether or not the planet has an atmosphere, or the atmospheric composition, or the exoplanet's albedo, etc. Granted, to have liquid water on the surface of any exoplanet requires a specific range of atmospheric pressure and temperature. But they are determining whether or not an exoplanet falls in the habitable zone based upon data they do not yet have. Would not a better approach be to use the Stefan–Boltzmann law to first determine whether or not an exoplanet falls in the right temperature range? Then when we learn more information, adjust the habitable zone for that specific exoplanet accordingly. If we use our sun and Earth as an example, and calculate the distance Earth must be (as a "black body") from the sun to have surface temperatures between 0°C and 100°C, we get: SQRT(((695,500,0002 x 5,7784) / 374.154) / 4) = 83,378,738,826 meters (0.56 AU) SQRT(((695,500,0002 x 5,7784) / 274.154) / 4) = 155,603,658,580 meters (1.04 AU) If we knew nothing about the conditions on Earth, then 0.56 AU to 1.04 AU seems like a reasonable first estimate. Once we learn of Earth's albedo (32.5% ± 2.5%), for example, we can adjust the habitable zone accordingly: (5,778 x SQRT( 695,500,000 / (2 x 149,597,870,700))) x 0.6750.25 = (5,778 x 0.04821) x 0.906412 = 252.5°K (-20.65°C) Again, the -20.65°C mean surface temperature only takes into account Earth's albedo, and does not include Earth's atmospheric composition and pressure. Since the current mean surface temperature of Earth is actually +14.8°C, then the 35.45°C difference must be the result of radiative forcing in the atmosphere due to greenhouse gases. Furthermore, the actual mean surface temperature of an exoplanet could tell us about its atmospheric pressure, once we learn about the exoplanet's atmospheric composition. It just bothers me when they make assumptions about whether or not exoplanets fall in the habitable zone of its star when they have no data about the exoplanet, other that it's orbit. They should be determining habitable zones based upon the information they actually have, until more is known, and leave out all the assumptions. What do you think? Or am I way out in left field?