All of this astronomical activity led to several important discoveries of how the positions of the stars in the sky change as a result of the motion of Earth around the Sun.
One of the effects of the way that Earth orbits the Sun is that over the course of a year nearby stars show a tiny annual back-and-forth motion called parallax. Parallax provides the most direct way to find the distance to a star. You see something like parallax when you walk from one place to another and notice that a nearby object like a tree seems to be in a differentposition against more distant background objects, say to the right of a building rather than lined up with the building. The farther you walk and the closer the tree is to you, the more it will seem to shift against the background. For many years astronomers knew that stars should show the same kind of change in position, and if they could measure a star's parallax they could calculate its distance. The distance we move (from one end of Earth's orbit to the other) is the same for all stars, and the closer a star is to us, the more parallax we should see compared to more distant stars.
This is a free page. This page contains 182 words. This
article contains 1,600 words (approx. 5 pages at 300
words per page).
Read the rest of this Article with our Nineteenth-Century Developments in Measuring the Locations and Distances of Celestial Bodies Access Pass.
