In the early twentieth century, astronomical models of the Milky Way polarized around two competing views of the cosmos: the Kapteyn Universe and the Shapley Model. Jacobus Kapteyn utilized star counts and proper motion statistics to construct a heliocentric system, concluding that the Sun lay near the center of a relatively small, ellipsoidal stellar system. In contrast, Harlow Shapley, investigating the spatial distribution of globular clusters, proposed a galactocentric model that placed the solar system far from the galactic core. While Kapteyn assumed interstellar space was entirely transparent—a premise that led him to underestimate galactic dimensions and place the Sun centrally—Shapley recognized the presence of light-absorbing dust but incorrectly assumed its effects were negligible at high galactic latitudes, thereby overestimating the galaxy's size by a factor of three. Furthermore, Kapteyn's model was fundamentally static, relying on a state of dynamical equilibrium, whereas Shapley’s model was dynamic, incorporating the asymmetrical rotation of globular clusters around a massive, distant nucleus.
Based on the passage, which of the following statements explicitly describes how Kapteyn and Shapley differed in their treatment of interstellar space?
- Kapteyn assumed interstellar space was completely transparent, whereas Shapley acknowledged the existence of light-absorbing dust but dismissed its influence in specific galactic regions.Answer
- BKapteyn believed that light-absorbing dust was negligible at high galactic latitudes, whereas Shapley assumed interstellar space was entirely transparent.
- CKapteyn argued that a transparent interstellar space led to an overestimate of the galaxy's size, while Shapley asserted that light-absorbing dust resulted in an underestimate of galactic dimensions.
- DKapteyn proposed that the solar system lay far from the galactic core due to dust absorption, whereas Shapley concluded the Sun was centrally located in an ellipsoidal system.