The astronomical fascination commenced at 2 a.m. ET on June 26, 2023, when researchers utilizing the advanced **James Webb Space Telescope (JWST)** aimed to study Kepler-51d, an unusual exoplanet with a remarkably low density, often referred to as “cotton candy-like.” To their surprise, the planet appeared two hours ahead of the expected time, an unexpected occurrence considering the usually predictable behavior of planetary orbits.
The enigma was quickly clarified: the gravitational effect of a newly discovered planet had altered Kepler-51d’s orbit. This finding increased the count of known planets orbiting the sun-like star Kepler-51, approximately 2,556 light-years away, to four. At least three of these planets exhibit the “puffy” trait, adding to the mystery of this star system.
“If elucidating how three super puffs formed in a single system wasn’t difficult enough, now we must consider a fourth planet, regardless of whether it is puffy. And we can’t dismiss the possibility of more planets existing in the system,” remarked Jessica Libby-Roberts, an astronomer at Penn State and the primary researcher on this study.
### An Unexpected Revelation
The results, recently disclosed in *The Astronomical Journal*, were derived from observations of Kepler-51d’s transit—when a planet crosses in front of its star, enabling scientists to investigate its atmosphere through a method known as **transit spectroscopy**. This technique involves capturing starlight that passes through the planet’s atmosphere, uncovering specific molecules like water based on the absorbed light.
Astronomers had projected that Kepler-51d would transit its star at 2 a.m. on June 26, 2023. However, even after starting their observations early, the anticipated drop in the star’s brightness did not occur as predicted. “Thank goodness we commenced our observations a few hours in advance to establish a baseline,” Libby-Roberts commented. “By 2 a.m. and even 3 a.m., there was still no indication of changes in brightness with the Apache Point Observatory (APO).”
Instead, the data showcased a dip in brightness around midnight, suggesting that Kepler-51d had arrived ahead of schedule. The team deduced that the gravitational attraction of a large, previously unidentified planet—now referred to as **Kepler-51e**—was the cause of the orbital shift. “We were quite baffled by the early appearance of Kepler-51d,” stated Kento Masuda, a coauthor of the study and associate professor at Osaka University. “No amount of adjusting the three-planet model could resolve such a significant inconsistency. Introducing a fourth planet was the only viable explanation. This marks the first planet identified through transit timing variations using JWST.”
### Insights on Kepler-51e
While it is still uncertain whether Kepler-51e is another “puffy” planet, astronomers are keen to collect more information during its subsequent transit. What is confirmed is that its orbit is positioned slightly farther than Venus’ orbit around the Sun, placing it near the outer edge of its solar system’s **habitable zone**—a region where liquid water might be present on a planet’s surface.
Puffy planets, like those found in the Kepler-51 system, pique scientific interest. They could eventually transform into denser planets, such as **super-Earths**, over time. With a minimum of three puffy worlds already acknowledged in this system, researchers are eager to uncover the secrets the fourth planet may unveil.
### The Capabilities of the James Webb Space Telescope
The James Webb Space Telescope, a partnership among **NASA**, **ESA**, and the **Canadian Space Agency**, is transforming our comprehension of the universe. While its design enables it to investigate the remote cosmos and examine the early universe, it is also proving vital for the exploration of intriguing planets within our galaxy.
Here’s how Webb is accomplishing these remarkable discoveries:
– **A Massive Mirror**: Webb’s 21-foot-wide mirror surpasses the Hubble Space Telescope’s by over 2.5 times in size, granting it the ability to gather much greater amounts of light. This feature allows Webb to observe ancient stars and galaxies that originated over 13 billion years ago, shortly following the Big Bang. “We’ll witness the very first stars and galaxies that ever came into existence,” stated Jean Creighton, an astronomer at the University of Wisconsin–Milwaukee.
– **Infrared Capabilities**: In contrast to Hubble, which primarily examines visible light, Webb is designed to focus on infrared light. Infrared wavelengths can penetrate cosmic dust clouds that scatter visible light, enabling Webb to “lift the veil” on areas of the universe that were formerly obscured.
– **Sophisticated Spectrographs**: Webb is furnished with state-of-the-art instruments that scrutinize the atmospheres of distant exoplanets. By detecting molecules such as water, carbon dioxide, and methane, scientists can glean insights into the composition and potential habitability of these planets.