parallax seconds造句

Parsec is short for'parallax second', and 1 parsec is the distance ( about 3.26 light years ) an object would be if the revolution of the Earth about the Sun over 6 months caused it to exhibit an apparent ( parallax ) shift in position angle of 2 arc seconds; or conversely, it's the distance at which a length of 1 Astronomical Unit ( see below ) would subtend an angle of 1 second.
It's difficult to find parallax seconds in a sentence. 用parallax seconds造句挺难的