Give a method for the measurement of large distance

unitsandmeasurement
cbse

#1

Let there be a planet P far away from earth. The planet is observed from two different observation points A and B on earth called observatories. If distance AB = b and angle APB = $\theta $ radian, then $\theta $ being verysmall b/D < < 1. Angle $\theta $ is called parallax or parallactic angle