Kepler-90i: A Glimpse into a Distant Super Earth
Kepler-90i, one of the intriguing planets discovered in the hunt for exoplanets, is part of the Kepler-90 system, located approximately 2,767 light-years from Earth. This system, named after the Kepler space telescope that discovered it, has proven to be a treasure trove for astronomers seeking to understand the diversity of planets beyond our Solar System. Kepler-90i stands out as a prime example of a “Super Earth,” a class of exoplanets that are larger than Earth but smaller than Uranus or Neptune. This article delves into the key features of Kepler-90i, exploring its characteristics, discovery, and its potential for scientific exploration.
Discovery and Location
Kepler-90i was discovered in 2017 as part of the Kepler Space Telescope’s ongoing mission to detect exoplanets using the transit method. The planet orbits a star named Kepler-90, which is a G-type main-sequence star similar to our Sun. The star lies in the constellation of Lyra and is located about 2,767 light-years from Earth. This relatively large distance poses challenges in studying Kepler-90i in detail, yet it remains an object of great interest due to the unique characteristics of its orbit and composition.
The Kepler-90 system, comprising at least eight planets, is often referred to as the “Solar System Twin” because it contains a similar number of planets as our own Sun’s system. However, the individual planets within the Kepler-90 system vary significantly from those in the Solar System, with Kepler-90i standing as one of the most significant in terms of its size and proximity to its star.
Orbital and Physical Characteristics
Kepler-90i is a Super Earth, a type of planet that typically has a mass greater than Earth’s but not quite as large as the gas giants like Uranus or Neptune. The planet is about 2.3 times as massive as Earth, indicating that it has a significantly higher gravitational pull. This higher mass likely results in a denser atmosphere and potentially higher surface gravity. Despite its larger mass, Kepler-90i has a radius that is only 1.32 times that of Earth, suggesting that its composition might be different from Earth’s, possibly with a thicker atmosphere or a more substantial core.
The planet’s orbital period—the time it takes to complete one full orbit around its star—is remarkably short, lasting only about 0.0394 Earth years, or approximately 14.4 Earth days. This places Kepler-90i in close proximity to its host star, resulting in higher surface temperatures. The planet’s orbital radius, however, is not precisely known, but it is inferred from its short orbital period that Kepler-90i orbits at a distance much closer to its star than Earth orbits the Sun. This close orbit likely results in extreme temperatures, making the planet an inhospitable environment for life as we know it.
Another interesting feature of Kepler-90i is its orbital eccentricity, which is zero. This means that the planet follows a nearly circular orbit around its star, in contrast to the elliptical orbits of many other exoplanets. The lack of eccentricity suggests that Kepler-90i experiences relatively stable gravitational forces, resulting in more predictable conditions compared to planets with highly elliptical orbits.
Transit Detection Method
Kepler-90i was discovered using the transit detection method, which involves observing the dimming of a star’s light as a planet passes in front of it. The Kepler Space Telescope, which was designed to monitor the brightness of stars across a vast area of the sky, can detect the small but measurable decrease in brightness caused by a planet transiting its star. This method provides valuable data about the planet’s size, orbit, and distance from its star, although it cannot directly measure the planet’s atmosphere or surface conditions.
The transit method has been instrumental in discovering thousands of exoplanets, including the Kepler-90 system’s eight planets. The precision of the Kepler telescope in detecting such minute changes in star brightness has revolutionized our understanding of the vast diversity of planets in the universe.
Potential for Habitability
Despite its classification as a Super Earth, Kepler-90i is unlikely to be habitable by Earth-like life. The planet’s proximity to its host star results in extreme temperatures, which likely preclude the existence of liquid water on its surface. The short orbital period also means that the planet is likely tidally locked, with one side always facing the star and the other in permanent darkness. This would create extreme temperature gradients between the day and night sides, further reducing the chances for habitability.
Additionally, the planet’s high mass and likely thick atmosphere could result in intense greenhouse effects, trapping heat and making the surface temperature even higher. These conditions suggest that Kepler-90i would be an inhospitable world, more akin to a hot, rocky exoplanet with conditions similar to Mercury or Venus in our Solar System.
Comparative Analysis with Other Super Earths
Kepler-90i is part of a growing list of Super Earths that have been discovered across the galaxy. Super Earths are intriguing because their size and composition allow them to potentially have conditions that differ significantly from the Earth. Some, like Kepler-90i, orbit very close to their stars, while others are located farther out, where conditions could be more moderate.
One of the key differences between Kepler-90i and other Super Earths is its orbital characteristics. Many Super Earths exhibit eccentric orbits, which can lead to extreme seasonal variations or dramatic shifts in temperature. Kepler-90i, however, has a circular orbit, which might make its environmental conditions more predictable, though still extremely hostile.
In terms of size and mass, Kepler-90i is on the smaller end of the Super Earth scale, with a mass 2.3 times that of Earth and a radius 1.32 times that of Earth. However, other Super Earths discovered by the Kepler mission have been found to be much larger, with masses up to ten times that of Earth. These larger Super Earths present even more extreme conditions and often require different methods of study to understand their composition and potential for supporting life.
Future Exploration and Study
Although Kepler-90i is far beyond the reach of current space exploration missions, its study provides valuable insights into the nature of planets in distant star systems. As technology advances, particularly with upcoming space telescopes like the James Webb Space Telescope (JWST) and future planet-hunting missions, scientists will be able to gather more detailed data on planets like Kepler-90i.
One of the main goals in exoplanet research is to better understand the diversity of planetary systems and the conditions that lead to the formation of planets like Earth. By studying Super Earths such as Kepler-90i, astronomers can refine models of planet formation, orbital dynamics, and atmospheric conditions, which are critical for identifying planets that might harbor life or otherwise be of scientific interest.
Conclusion
Kepler-90i, as a Super Earth located in the distant Kepler-90 system, offers an exciting glimpse into the variety of planets that exist beyond our Solar System. While it is unlikely to be a hospitable world due to its extreme temperatures and close orbit to its host star, the planet provides valuable data for understanding planetary systems and their evolution. As observational technology improves, the study of planets like Kepler-90i will continue to shape our understanding of exoplanets, bringing us one step closer to unraveling the mysteries of the cosmos.
The discovery of Kepler-90i and its peers emphasizes the importance of missions like Kepler, which have dramatically expanded our knowledge of exoplanets. While the search for Earth-like worlds continues, Kepler-90i serves as a reminder of the vast and varied landscapes that exist across the universe, many of which may hold secrets about the conditions that shape planetary systems and the potential for life elsewhere in the cosmos.