I would like to preface this by stating that I am not very well-versed in cosmology or astrophysics, but I've been thinking: I understand the idea of parallax, both in the sense of human eyes measuring distances to nearby objects and in the sense of telescopes on earth (or in orbit) measuring the distance to nearby stars. From my understanding, it is all about angle. In the case of human eyes, a very nearby distance has photons entering the eye at a very steep angle with respect to the normal while photons from far away objects enter the eye at much more shallow angle with respect to the normal. This change in angle allows us to estimate distances to distant objects. In the case of measuring the distance to nearby stars, the idea of using two eyes is exactly identical, except these "two eyes" is just the earth being at different places in space as it orbits the sun - opposite sides of the sun every 6 months. However, since the Earth's orbit is fairly small, especially compared to some of these astronomical distances, this must only be sensitive for the more nearby stars. My question is this: Once you begin looking at objects more distant than these further stars we can measure distances to with parallax, does size matter? That is, for example, our nearest galaxy is located much further away than the nearest stars, but the galaxy is also much larger. Does the added size (or area, maybe?) of the object we are trying to measure distances to with parallax make it easier for this technique to work? Thanks in advanced.