About 185 light-years away, researchers have discovered an Earth-sized planet orbiting a dim red star. The official name for the planet is K2-315b but scientists have taken to calling it "Pi Earth", a reference to it's orbit which circles its star every 3.14 days. Astronomers don't know much about the atmosphere or inner workings of the planet, they attempted to estimate the heat of the planet as if it were a simple dark ball heated just by a star; their calculations came out to be about 187º Celsius (368º Fahrenheit). 

Prajwal Niraula is a planetary scientists who focuses on exoplanets, he and his team were the ones who wrote about "Pi Earth" in The Astronomical Journal. They discovered the new planet by examining data from NASA's K2 Mission which concluded in October 2018 when the spaceship ran out of fuel. While looking through the data, they noticed an object and set out to investigate. Using historical images of the sky and a network of ground-based telescopes they were able to confirm the object was, indeed, a planet.

Johanna Teske is an astronomer who studies exoplanets at the Carnegie Institution for Science in Washington, D.C. She stated that, "This study presents a new, fairly temperate [rocky] planet around a low-mass, cool star." The star that Pi Earth orbits has a surface temperature of about 3,000 ºC (5,500 ºF) which is cooler than most stars; for example, the sun Earth orbits is about  5,500º Celsius (10,000º Fahrenheit). Although, if estimates are correct Pi Earth is still to hot to be habitable. 

Pi Earth was discovered as a survey to find cool stars specifically in order to find small planets. "Small planets are easier to detect around smaller stars because they block out a higher fraction of the star's light." Teske says. In order to measure Pi Earth's size, astronomers had to measure how big a shadow it casts as it made passes around its star. Niraula's team then inputted the data into a computer model to calculate the size. According to Teske, astronomers are interested in planets around cool stars because it's the best chance we have at finding "temperate" planets. These planets are often referred to as being in the "Goldilocks Zone" which Teske describes as planets that "are cool enough to have liquid water on the surface".

Niraula and his team are excited to continue studying Pi Earth's atmosphere. By studying the atmosphere they can potentially get a better understanding of what the planet itself is made of. With this information, Niraula says, "You can make a lot of inferences, such as, like, 'Is there life there?'"

source: sciencenewsforstudents.org