Why was simple trigonometric parallax inadequate for measuring the distance to the Andromeda Nebula (M31)?
Answer
The angle shift across intergalactic space would be far too small to detect
Trigonometric parallax functions as a measuring stick based on geometry, relying on observing a shift in a star's apparent position as the Earth orbits the Sun. This method works well for stars relatively close within the Milky Way. However, for objects deemed to be at intergalactic distances, like the Andromeda Nebula, the resultant angle of shift is infinitesimally small—too minute to be measured accurately with the instrumentation available or even theoretically possible due to the resulting angular uncertainty. Therefore, a completely different, intrinsic stellar property—a standard candle—was required to bypass geometric limitations.
Related Questions
What instrument did Edwin Hubble utilize at Mount Wilson Observatory to resolve stars in the Andromeda Nebula?What specific stellar characteristic, measured by Henrietta Swan Leavitt, allowed Hubble to determine the intrinsic brightness of Cepheids?Why was simple trigonometric parallax inadequate for measuring the distance to the Andromeda Nebula (M31)?What was the designation given to the specific Cepheid variable star Hubble identified within the Andromeda Nebula in 1923?What were the two critical brightness measurements Hubble compared to solve the final distance to V1 using the inverse square law?According to Hubble's initial calculation, approximately how far away was the Andromeda Nebula from the Milky Way?What concept did the discovery of V1 confirm about the Andromeda Nebula (M31) relative to the Milky Way?Which astronomical entity was believed to encompass nearly the entirety of the known universe before Hubble's work resolved the spiral nebulae debate?What type of Cepheid stars were later found to be responsible for the initial underestimation of Andromeda's distance?What term describes standard celestial objects like Cepheids, whose intrinsic brightness is tied to a measurable timing property, used for gauging vast cosmic distances?