: You point two telescopes at the object u want to measure the distance too, one of the telescopes is on each side of the earth. We know the radius f the earth, so we can use trigonometry and the angle at which the telescopes point relative to the earth to calculate the distance from the centre of the earth to the distant object :/ hope that helped.

: Iain

I under this triangle-method.

But how long distance it is enough accurace?