Parallactic second or parsec is a unit of large distances used by the astronomers to measure large distances outside our solar system. One parsec is defined as the distance between the line drawn from the centre of the Earth and the Sun making an angle of 1 second with each other.

What is Parallactic second what is its value?

Answer: Parallactic second or parsec is the distance at which length of one astronomical unit subtends an angle of one second of an arc. It's value is 1parsec(parallactic second)=3.1×10^16metres.

What is a parallax second used for?

It is used to measure the distance of an astronomical object from the Earth. A star which has an annual parallax of one second of an arc is considered to be one parsec (3.26 light years) distant from the earth.