# s13:pi

“Özge'nin gözünden yuvarlanarak akan bir yaş, yanağının kenarından eğimli bir şekilde kayıp dudaklarına kondu. Çatık kaşlarının altında acıyla kısılan gözlerini sildi elinin tersiyle. Sadık o el olmak istedi, onun gözlerini silmek, dudağına konan o damlaya ulaşmak istedi…”

Happy Pi day! And happy birthday, Albert Einstein! :D

Pi Guides the Way

## What Is Pi ?

Pi is the ratio of a circle’s circumference to its diameter. It is also an irrational number, meaning its decimal representation never ends and it never repeats. Pi has been calculated to more than one trillion digits,

## Why March 14?

March 14 marks the yearly celebration of the mathematical constant pi. More than just a number for mathematicians, pi has all sorts of applications in the real world, including on our missions. And as a holiday that encourages more than a little creativity – whether it’s making pi-themed pies or reciting from memory as many of the never-ending decimals of pi as possible (the record is 70,030 digits).

While 3.14 is often a precise enough approximation, hence the celebration occurring on March 14, or 3/14 (when written in standard U.S.  month/day format), the first known celebration occurred in 1988, and in 2009, the U.S. House of Representatives passed a resolution designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi.

## 5 Ways We Use Pi at NASA

Below are some ways scientists and engineers used pi.

## Keeping Spacecraft Chugging Along

Propulsion engineers use pi to determine the volume and surface area of propellant tanks. It’s how they size tanks and determine liquid propellant volume to keep spacecraft going and making new discoveries.

## Getting New Perspectives on Saturn

A technique called pi transfer uses the gravity of Titan’s moon, Titan, to alter the orbit of the Cassini spacecraft so it can obtain different perspectives of the ringed planet.

## Learning the Composition of Asteroids

Using pi and the asteroid’s mass, scientists can calculate the density of an asteroid and learn what it’s made of–ice, iron, rock, etc.

## Measuring Craters

knowing the circumference, diameter and surface area of a crater can tell scientists a lot about the asteroid or meteor that may have carved it out.

## Determining the Size of Exoplanets

Exoplanets are planets that orbit suns other than our own and scientists use pi to search for them. The first step is determining how much the light curve of a planet’s sun dims when a suspected planets passes in front of it.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Happy #PiDay 🍰

Happy Pi Day!

Oh 3.14159265…, you’re irrational but we love you anyway.

Happy Pi Day Everyone!

3.1415926535897932384626433832795028841971693993751058209749445

92307816406286208998628034825342117067982148086513282306647093

84460955058223172535940812848111745028410270193852110555964462

29489549303819644288109756659334461284756482337867831652712019

Mind blown.
Happy pi day!!

Man hat den Schulabschluss geschafft und denkt: Jetzt bin ich erwachsen und es geht los in die große Welt und man sollte sich eigentlich mega gut fühlen. Aber irgendwie kommt dieser Moment einfach nicht.
—  Prinz Pi - Interview
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Essential 90’s Films: Part I

## Happy pi day!

Unlike us, echinoderms like sea urchins have what is known as radial symmetry – meaning they’re symmetrical around a center point, like a pie. These purple and red sea urchins were observed in Greater Farallones National Marine Sanctuary off the coast of California.

(Photo: Steve Lonhart/NOAA)

Happy Pi Day from Margaret, our hyacinth macaw! She celebrated with her very own “pie” enrichment activities.

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Happy Pi DAY!

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Celebrating Pi day with a little pie!

Happy Pi Day!

Apple pie made by the amazing @klassykraves check her out on Instagram!

“Tehlike sen görmezlikten geliyorsun diye geçen bir şey değildi!”

Happy Pi day!

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The day about foo- I mean, math.

Neil deGrasse Tyson rapping the digits of Pi for Pi day.