Just a few decades ago, planets outside our Solar System were little more than a guess in the minds of the most optimistic astronomers. However, thanks to the most ambitious space missions in history, such as Kepler, Spitzer, and, more recently, the James Webb Space Telescopes and other ongoing projects, exoplanets have become a fundamental part of modern space knowledge and exploration. Each discovery represents a technological leap, and an opportunity to change our perspective on life in the universe.
Progress in the search for other worlds has been closely linked to the evolution of astronomical technology and international collaboration, allowing us to identify from Earth's twin planets to solar systems with unique characteristics, such as the famous TRAPPIST-1In this article, we'll take an in-depth look at the most notable exoplanets discovered by space missions, focusing on everything from the legacy of the Kepler mission to recently discovered systems like TRAPPIST-1, while also considering the contributions of artificial intelligence and future missions.
A new chapter in exploration: How did exoplanet search missions begin?
Before the exoplanet revolution, science fiction was the refuge of star systems teeming with diverse worlds. Although astronomers suspected the existence of planets outside the Solar System, It was not until the 1990s that the first conclusive evidence was obtainedInitially, gas giants were discovered, very different from what we expected and not very similar to Earth.
The big push would come with the mission Kepler NASA's. Launched in 2009 after years of technical obstacles and institutional pushback, Kepler had a mission as simple as it was ambitious: to monitor the brightness of more than 150.000 stars, using a high-precision photometer, and search for the tiny light fluctuations caused by a planet's transit in front of its star. Despite its modest beginnings, Kepler forever changed our view of the cosmos.
For years, the scientific team struggled to turn this unprecedented technical proposal into reality, facing institutional skepticism and technological challenges. The test bench developed at Ames, which demonstrated that charge-coupled devices could achieve the desired precision, is now on display as a a key piece of aerospace history.
The Kepler Revolution: Thousands of Exoplanets and a Galaxy Full of Worlds
When Kepler was launched, they were barely known less than 400 exoplanets, most of them massive, blazing-hot worlds. However, within a few years, telescope data confirmed more than 5.500 exoplanets, half of which were discovered thanks to this mission.
Kepler not only increased the number of planets discovered outside the Solar System by tens of thousands, but also allowed the identification of hundreds of planets located in the "habitable zone.", that is, at the appropriate distance where water could exist in a liquid state. This condition It is essential to host life as we know it.
Among Kepler's most significant discoveries are planets with sizes and conditions close to Earth's. Of the 4.034 exoplanets detected since its launch (2.335 confirmed by other telescopes), nearly 50 are in the habitable zone and share a size similar to ours. More than 30 have been validated by independent observations. which represents an unparalleled statistical and scientific leap.
The discovery of the system also stands out kepler-90, which with its eighth planet discovered, equaled the Solar System in number of planets orbiting the same star. The planet kepler-90i, a fiery, rocky world, was found using an innovative method based on machine learning, showing that Artificial intelligence will be indispensable in the future of astrophysics.
Kepler's way of detecting planets was ingenious and efficient: by recording a drop in a star's luminosity caused by a periodic transit of a planet, it was able to deduce not only its presence, but also its mass, size, and orbital distance. This method, combined with the automatic analysis of thousands of data points, accelerated the pace of discoveries explosively.
The impact of artificial intelligence on the search for exoplanets
The arrival of artificial intelligence has meant a revolution in modern astronomy. Thanks to machine learning techniques, advanced algorithms and neural networks, the scientific community can manage volumes of astronomical data that are impossible to analyze manually..
In Kepler's case, these advances made it possible to discover planetary signals that had gone undetected using traditional methods. Researchers such as Christopher Shallue and Andrew Vanderburg trained neural networks with more than 15.000 classified signals, achieving a 96% success rate in identifying real exoplanets versus false positives related to stellar or binary phenomena.
This approach made it possible to detect the planet kepler-90i and the Kepler-80g, in addition to optimizing the analysis of the more than 150.000 records in the Kepler catalog. Artificial intelligence has not only improved detection efficiency, but will also allow for the identification of weaker and more complex signals in multiple systems in the future.
Paul Hertz himself, director of Astrophysics at NASA, highlighted the importance of this strategy, ensuring that the stored data from Kepler will be a a true treasure for future research.
From Kepler to TESS and Beyond: The Future of Exoplanet Hunting
Kepler's success was not the end. The project was subsequently launched. K2, which expanded the search to different regions of the sky. Since 2018, the Transiting Exoplanet Satellite Survey (TESS) has observed 200.000 stars near our cosmic neighborhood, using methods similar to Kepler's but with greater coverage and sensitivity, especially for Earth-sized or smaller planets.
Other missions underway or in development, such as the James Webb Space Telescope (JWST), the Roman Space Telescope, ARIEL y PLATO, promise not only to find new exoplanets, but also to analyze their atmospheres in detail, identifying gases such as oxygen or methane, which could be indications of biological activity.
Community participation in citizen science projects, such as Zooniverse, complements scientific work, allowing thousands of amateurs to contribute to the identification of distant worlds.
TRAPPIST-1: An Extraordinary Solar System
The discovery of the system TRAPPIST-1 In 2016, it marked a milestone in astronomy. It is an ultra-cool dwarf located about 40 light-years away in the constellation of Aquarius, with seven planets of similar size to EarthThe discovery, led by Michaël Gillon, was made using the TRAPPIST telescope, consolidating international collaboration and work with ground-based and space-based instrumentation.
All planets orbit very close to their star, in less than twenty Earth days, and Three of them are located in the habitable zoneThe proximity generates gravitational variations and orbital resonances, allowing prominent neighbors in the sky to be observed from the surface.
The observations involved large telescopes such as Spitzer and Kepler, as well as multiple ground-based observatories. During the "K2 12" campaign, Kepler observed the star for 74 consecutive days, obtaining key data to determine its orbital characteristics. Now, the James Webb Space Telescope studies the atmosphere of TRAPPIST-1b, initially ruling out a dense atmospheric layer.
The analysis suggests that some of these planets could be rocky or have water, ice, or significant atmospheres. In particular, TRAPPIST-1e It stands out for its density and structural similarities with Earth, which reinforces its interest for habitability studies.
Life outside the Solar System? Habitable zones and their challenges
One of the biggest questions these missions address is whether other worlds can support life. The "habitable zone" of a star corresponds to the region where liquid water can be maintained on the surface, a key condition for known biology.
In systems like TRAPPIST-1 or Kepler, several planets have been located in this zone. However, habitability also depends on factors such as the atmosphere, magnetic field, stellar radiation, and geological history.
Red dwarfs, like TRAPPIST-1, emit frequent flares and radiation that can modify or erode atmospheres. If planets in the habitable zone retain an ozone layer, they could maintain Earth-like environments. Otherwise, ultraviolet radiation could make microbial life difficult on their surfaces.
Advances in atmospheric detection and analysis allow us to exclude hydrogen atmospheres in some cases, indicating compositions more similar to those of Earth or Venus. The detection of molecules such as oxygen and ozone through spectra will be crucial for identifying possible biological processes on these worlds.
Orbits, resonances and chains of exoplanets
The structure of systems like TRAPPIST-1 is surprising. The seven planets orbit much closer to their star than Mercury orbits the Sun., forming chains of stable orbital resonance, choreographed by their gravitational interactions.
The inner planets maintain near-harmonic ratios in their orbits, such as 8:5 or 3:8. These resonances allow us to precisely determine their masses and densities, which in many cases are similar to those of Earth, suggesting they could be rocky and contain water.
These worlds are thought to have formed beyond the ice line and migrated inward, trapped in these resonances. These migrations increase the likelihood that they contain water and other volatiles, increasing their interest in habitability.
Exoplanets and citizen science
The enormous amount of data from missions like Kepler, TESS, and ground-based telescopes makes citizen participation essential. Projects like Zooniverse allow anyone to help in the search for exoplanets., analyzing light curves and detecting patterns that are then validated by scientists.
This approach not only accelerates discoveries, but also brings space exploration closer to everyone, democratizing knowledge and science.
Legacy and future challenges
The impact of these missions goes beyond counting exoplanets. Kepler has shown us that there may be more planets than stars in the galaxy.The existence of systems like TRAPPIST-1 or Kepler-90, with characteristics very different from our own, broadens our understanding of planetary diversity and raises new questions about their formation and habitability.
The future is bright: improved instrument sensitivity, the arrival of missions like Roman, ARIEL, and PLATO, and the increasing use of artificial intelligence ensure that we will discover new worlds in the coming decades.
The search for life, even in microbial forms, remains one of the greatest drivers of exploration. The current data, available to researchers and the general public, lays the groundwork for future generations to continue exploring and dreaming of other worlds.
As we explore the universe, the possibility of finding life somewhere increases, reinforcing the idea that we are not so alone. The legacy of Kepler, TRAPPIST-1, and future missions guarantees both scientific and human exploration, full of surprises and discoveries.
