Parallax isn't only an optical illusion that makes planes look like they're hovering — or a tool your brain uses for depth perception in everyday life. Astronomers use parallax to determine the ...

The difficulty results from the lack of parallax with only one eye. Have advanced students use astronomy reference books to pick a constellation and identify by name the stars in the constellation.

A parsec is a unit of distance used in astronomy, equivalent to approximately 3.26 light-years, or about 19 trillion miles. The term comes from “parallax of one arcsecond.” It is based on the ...