This Earth-Sized 'Pi Planet' Orbits Its Host Star In 3.14 Days

Astronomers spotted a rather interesting planet that orbits its host star every 3.14 days. This "pi planet" is similar to Earth in size but is likely not habitable.

In 2017, NASA's Kepler Space Telescope observed a patch of the sky as a part of its mission to survey our region of the Milky Way to explore planetary systems. From this data, the lead of a new study, Prajwal Niraula of the Massachusetts Institute of Technology (MIT), spotted a cool dwarf star dubbed EPIC 249631677 that appears to have a signal that repeats every 3.14 days.

Using the ground-based The Search for habitable Planets EClipsing ULtra-cOOl Stars (SPECULOOS) telescopes, which search for planets around stars by the dips in the stars' brightness, Niraula and other members of the SPECULOOS research team had a closer look at the star, observing it for several nights last February. And indeed, the researchers were able to confirm that a planet orbits EPIC 249631677 every 3.14 days, clearly reminiscent of the famous mathematical constant.

In fact, they've dubbed the planet "π Earth" in the title of the study.

"Everyone needs a bit of fun these days," study co-author Julien de Wit, also of MIT, said in the news release from the research university.

Based on the researchers' observations, the planet now dubbed K2-315b is possibly a terrestrial planet that has a similar size to Earth and, it orbits a star that's just about a fifth the size of the sun.

Its similarity with Earth ends with its terrestrial structure and size, however, because K2-315b orbits so fast that it moves some 181,000 miles per hour and so closely that even if its host star is considered "cool," the surface of the planet would be heated up to 350 degrees Fahrenheit. This means that the planet is likely too hot to be habitable.

"(P)erfect, as it turns out, for baking actual pie," the MIT news release writes.

Interestingly, the news release notes that the planet is a part of the 315th planetary system to be observed in the K2 data. If it had been discovered earlier, it would perhaps have been the pi planet in a pi system.

According to the researchers, this "pi planet" could be an excellent candidate to be observed by the upcoming James Webb Space Telescope (JWST), which is set to launch in October 2021.

"There will be more interesting planets in the future, just in time for JWST, a telescope designed to probe the atmosphere of these alien worlds," Niraula said in the MIT news release. "With better algorithms, hopefully one day, we can look for smaller planets, even as small as Mars."

The study is published in the Astronomical Journal.