Parallax and angular measure

What is parallax? How does parallax relate to distance an object in space? What is angular diameter? If you know the angular diameter of an object and the distance to the object, what other quantity can you calculate?


Whenever the position of view is changed, the object which is being viewed appears to be in different direction or position . This effect is known as Parallax. The parallax  is larger if the if it is closer to the observer and smaller if the object is far. Since the object in the space is far away from the earth, the parallax is small.

The angular diameter is the distance to an object which is defined in terms of object's actual size and the angular size of the object as viewed from the earth. If we have parallax and angular diameter we can find Liner diameter.