In many parts of the world, March 14th, the 14th day of the 3rd month, is celebrated as "Pi Day" every year.
This is because 3.14 is the first digits of Pi. Math enthusiasts around the world love to celebrate this infinite and never-ending number. Pi Day, which was first celebrated in 1988 at the San Francisco Exploratorium by Larry SHAW, a famous physicist, was first celebrated in our country in 2007.
Pi, named after the symbol π, the first letter of the Greek word for circumference, is the ratio of the circumference of a circle to its diameter. No matter how big or small a circle is (from the size of our universe to the size of an atom or smaller), the ratio of the circumference of a circle to its diameter is always equal to Pi.
Pi is usually rounded to 3.14 for simplicity, but its digits go on forever and do not have any repeating pattern.
Calculating the digits of Pi is one of the greatest joys of mathematicians. Until 1900, these calculations were done manually, but with the introduction of computers, it became a festival. In 2019, Emma Haruka Iwao, a Google developer in Osaka, Japan, set a world record by calculating the lower digits of the infinite number Pi to 31 trillion digits with the help of Google's cloud computing systems.
Since its discovery, Pi has been in our lives in many fields such as engineering, construction, GPS, simulation, radio, TV, telephone and energy production. Some historians are even debating whether Pi was used in the construction of the ancient Pyramids of Giza, as the structures are almost geometrically perfect.
Pi is also very important for space exploration. Let's take a look at some of its uses.
THE IMPORTANCE OF PI IN SPACE EXPLORATION
- Scientists study the physical structure of planets and asteroids by determining their volume, density and mass using Pi.
- Space explorers use Pi to search for exoplanets orbiting stars other than the Sun. Powerful ground- and space-based telescopes monitor how much light distant stars emit. When a planet passes in front of its star, the telescope sees a drop in the amount of light emitted. Scientists can determine the size of the planet using the percentage of this decrease and the formula for the area of a circle in Pi.
- To put a spacecraft into orbit around a planet, the spacecraft must be slowed down by the planet's gravity just enough and at exactly the right time to be pulled into orbit. Engineers determine how much this gravity will pull the spacecraft, how fast the spacecraft goes and the details of the new orbit. Using these numbers together with Pi, they can calculate exactly how much they need to apply the brakes.
- The Cassini spacecraft spent 13 years orbiting Saturn, observing the planet's majestic rings, moons and surface features. Twice during this mission, engineers used a technique called Pi transfer to change Cassini's orbit. Cassini's orbit was flipped 180 degrees to the opposite side of the planet in a directed pass. This allowed Cassini to see the planet and Titan in a whole new light.
- While no two Mars landings are exactly the same, they all share one thing in common: parachutes. Just like the Perseverance spacecraft that landed on, the surface of Mars on February 18, 2021, the spacecraft must be slowed down for a soft landing on the Martian surface. When designing a parachute, engineers have to take into account all kinds of factors such as the mass of the spacecraft, its speed, and the height of the landing site. The number pi helps engineers determine the size of the parachute to create the drag needed to slow the spacecraft down.
- Engineers use Pi to estimate the amount of uncertainty in the location where a Mars lander or rover will land. Landing on Mars is uncertain for many reasons, including winds, air density, the initial speed and position of the spacecraft as it approaches Mars from Earth. Prior to the Mars landing, many of these uncertainties can be modeled using mathematical distributions that include Pi in the calculations. When simulated together, the result is potentially kilometers of location uncertainty surrounding the intended landing spot. Engineers take this uncertainty into account and are careful where they aim, as was the case with the Perseverance rover that landed in the Jezero crater.
- Engineers use Pi to communicate with spacecraft in the deep space network to send messages and process what is sent back. Sending and receiving messages to and from distant spacecraft requires a network of massive antennas placed around the world. Together, these antennas make up NASA's Deep Space Network, or DSN. Engineers communicating with the spacecraft through the DSN use Pi in the math equations needed to send messages and process the ones sent back.
- The Mars rovers do not have joysticks or a steering wheel that can be used to steer them. Instead, the rovers receive commands from operators on Earth telling them when and how to move forward, take photos, turn their wheels and use their robotic arms. Some of these functions are measured in degrees and others in radians (circle slices), so Pi is regularly used to convert between the two.
- When scientists discover new exoplanets, one of the most important things they want to know is whether these worlds can support life as we know it. A "potentially habitable" area is a location at a safe distance from the star, close enough for water to turn into gas and not so far away that water turns into ice. Scientists use Pi to find the inner and outer edges of the habitable zone around a given star. And they use Pi, together with Kepler's third law, to calculate how long it takes an exoplanet to reach the orbit of its star, thus revealing its position and whether it is in the habitable zone.
- Pi is critical in calculating how much fuel is in spacecraft tanks and how fast the fuel travels through fuel lines.
- Just like Earth's ancient explorers, when spacecraft visit other planets and worlds, they make a map. Scientists use Pi in the surface area formula to work out how many images it would take to map the entire planet.
INTERESTING FACTS ABOUT THE NUMBER PI
- Pi has been known and used by civilizations for about 4,000 years. The cute symbol for pi was introduced in 1706 by William Jones, an Anglo-Gaelic philologist (linguist) and has been in our lives for over 250 years.
- The exact value of pi can never be calculated, so we can never clearly express the circumference of a circle numerically.
- Many mathematicians believe that it is more accurate to say that a circle has infinite vertices than to say that it has none. They think it is reasonable to assume that an infinite number of vertices in a circle is related to the infinite number Pi.
- A Turkish mathematician, Gıyaseddün Cemşid Al-Kashi of Samarkand, first calculated the value of Pi to 16 decimals in 1436.
- People compete to calculate more Pi digits in a never-ending contest. In 2010, a Japanese engineer and an American computer wizard set the record for the most Pi digits, calculating Pi to 5 trillion digits. They used only desktop computers, 20 external hard disks and their brilliant minds for the calculations.
- The record for reading the most decimal places of Pi was set by Rajveer Meena at VIT University in Vellore, India, on March 21, 2015. Rajveer was able to read 70,000 decimal places and it took 10 hours!
- The pyramids, enigmatic structures declared as one of the seven wonders of the world, were built with Pi calculations.
- There is a language made of the number Pi. Some people loved Pi enough to invent a dialect. In "Pi-lish", the number of letters in each word matches the corresponding number Pi. The first word has three letters, the second has one letter and the third has four letters. This language is much more popular than you might think.
- Calculating Pi is a stress test for a computer. The graph showing the level of activity in the computer's processor works just like a digital cardiogram.
- Pi is an irrational number, meaning that the digit after the comma has no limit. Since this unbounded sequence of numbers never repeats itself, the numbers have always been arranged in different ways. Pi is literally infinite. But the number 123456 appears nowhere in the first million digits of Pi. This is a bit shocking because if one million digits of Pi does not have the sequence 124356, it is certainly the most unique number.
- Albert Einstein, one of the world's most famous scientists, was born on March 14, 1879.
- Even though we know trillions of pi digits, it's not really needed; even engineers at NASA round Pi to 15 decimal places when calculating interplanetary orbits.
In the past, we have celebrated Pi Day with various activities at Space Camp Turkey. Participants from the international camp program from the American School in Lahore, Pakistan, learned the meaning of Pi Day, the importance of the number Pi and its place in mathematics with a special lesson, as the 14th day of the 3rd month (3.14) is accepted and celebrated as "World Pi Day" on March 14 every year. Students learned that Pi (the Greek letter "π") is a constant in mathematics and is the symbol used to represent the ratio of approximately 3.14159. They celebrated Pi Day at Space Camp Turkey with various math games and fun activities, and took a "Pi Day Souvenir Photo".
Happy Pi Day!