Both earth and the planet venus have a large amount of water vapor in the atmosphere, and have extensive volcanic activity throughout history. does this observation support or disprove the inside-out model? supports, because venus is near earth and would have been hit by all the same comets. disproves, because a single observation can discredit a theory. disproves, because data taken on venus is not applicable to earth. supports, because it shows that volcanic activity may be related to water vapor.