- Mar 14, 2019
- 1 min read

π in Astronomy

Spacetime

PI DAY: HOW π IS USED IN ASTRONOMY

There really is something about Pi. It is one of those things being present everywhere at all times. It is subtly ignored on a daily basis unless it needs to be pointed out. Like breathing. Until someone says “take a breath” and you start breathing consciously.

The 14. of March is a reminder, that π really is something special. A mathematical constant that can not be written with the final number of integers, fractions, or their roots. It is 3.1415926535897932384626433… or approximately 3,14.

WHERE THERE ARE CIRCLES, THERE IS π

Pi is represented by a Greek letter π. It is originally defined as the ratio of a circle's circumference to its diameter.

The circumference of the circle with radius r is 2 π r.

The surface of the circle with radius r is π r^2.

The volume of the sphere with a radius r is (4/3) π r^3.

Observing angles, 180 degrees corresponds to π.

When we observe circular motion, π plays its role. Understanding and using π is very important for progress in many sciences, particularly in astronomy.

No wonder, since there are circles and spheres everywhere: planets, solar systems, galaxies, stars, orbits. Round objects circling, rotating, orbiting each other. If you are looking for an answer in outer space, π is sooner or later going to show up in the equation.

It also appears in Einstein's equations of general theory of relativity. It is part of an equation describing fundamental force of gravitation as a result of spacetime being curved by matter and energy.