For decades, astronomers have searched the skies for planets orbiting distant stars. Now, researchers are developing tools that could help them look for something far more unusual: artificial structures built by advanced alien civilizations.
Researchers Bhowmick and Khaire have developed a numerical simulator called Yuti, a powerful tool designed to model the way objects of almost any shape block the light of a star. Unlike conventional transit models that mainly focus on spherical planets, Yuti can simulate objects with complex and unusual geometries—including comets, distorted planets, binary stars and hypothetical alien megastructures.
The goal is simple but exciting: understand what these unusual objects would look like when they pass in front of a star, and determine whether their distinctive signals could eventually be identified in real astronomical data.
From the First Exoplanet to Thousands of Discoveries
The discovery of 51 Pegasi b in 1995, the first exoplanet found orbiting a Sun-like star, transformed astronomy. Since then, scientists have developed increasingly sensitive instruments to discover and study planets beyond our Solar System.
The launch of NASA's Kepler Space Telescope in 2009 and the Transiting Exoplanet Survey Satellite (TESS) in 2018 made the transit method one of the most successful techniques for finding exoplanets.
The method is relatively straightforward. When a planet passes between its host star and an observer, it blocks a tiny amount of the star's light. Astronomers measure this small decrease in brightness and create a graph known as a transit light curve.
The shape and depth of this curve can reveal important information about the object, including its size and orbit.
But transit observations can reveal much more than ordinary planets.
Transit Light Curves Can Reveal Strange Cosmic Objects
Over the years, astronomers have used transit photometry to study phenomena such as starspots, interactions between stars and planets, orbital changes and additional planets that do not directly transit their host stars.
Transit observations have also contributed to the study of disintegrating planets, exocomets and possible exomoons.
This means that a light curve is not simply a way to discover a planet. Its detailed shape can contain clues about the physical properties and behavior of the object passing in front of a star.
That raises an intriguing possibility.
What if the object creating an unusual light curve isn't a natural planet at all?
Searching for Signs of Alien Engineering
Scientists searching for evidence of advanced extraterrestrial technology use the term technosignatures. These are potentially detectable signs of technology that could not easily be explained by ordinary natural processes.
One theoretical example is the Dyson Sphere, a concept proposed by physicist Freeman Dyson involving a civilization constructing structures around a star to capture a significant portion of its energy.
A complete solid shell is generally considered an impractical interpretation of the original idea, but researchers have explored more physically plausible concepts, including Dyson swarms—large collections of independent structures orbiting a star.
If such enormous structures existed around another star, they could potentially produce unusual patterns in the star's brightness.
The challenge is determining what those patterns would look like.
That's where Yuti becomes particularly interesting.
How Yuti Works
Yuti uses a Monte Carlo simulation technique to calculate how much stellar light is blocked when an object crosses the face of a star.
Instead of restricting the transiting object to a simple spherical shape, the simulator can work with arbitrary geometries.
This gives researchers much greater freedom when creating models.
The simulator can also account for realistic properties of stars, including limb darkening. Stars are generally brighter near their centers and appear darker toward their edges. This effect changes the exact shape of a transit light curve and therefore needs to be included when making realistic simulations.
Yuti can also model rotational behavior and other changes in the geometry of the transiting object.
The result is a simulated light curve that researchers can compare with astronomical observations.
From Planets to Exocomets
The researchers demonstrated that Yuti can reproduce light curves from ordinary planetary systems.
It can model the transit of a single planet as well as systems containing multiple planets, including the TRAPPIST-1 system.
But the simulator's capabilities go beyond conventional planetary transits.
The researchers also used Yuti to model tidally distorted planets and binary stars. Strong gravitational interactions can deform astronomical bodies, meaning that their silhouettes may not remain perfectly spherical.
Yuti can represent these more complicated shapes and calculate the resulting changes in the star's brightness.
The simulator was also used to model an exocomet candidate, KIC 3452116.
Comets can create unusual transit signatures because they may have extended tails rather than compact, spherical bodies. Their light curves can therefore look very different from those produced by ordinary planets.
These examples demonstrate why a flexible geometry-based simulator can be useful for studying unusual astronomical events.
Modeling Alien Megastructures
Perhaps the most futuristic application of Yuti involves hypothetical structures constructed by advanced civilizations.
The researchers demonstrated simulations of several proposed megastructure concepts, including a Dyson swarm and Dyson ring.
A Dyson swarm could consist of many individual structures orbiting a star. As these objects move across the observer's line of sight, they could produce complex changes in the star's brightness.
Yuti allows researchers to experiment with different shapes, sizes and arrangements to determine what these signals might look like.
The researchers also introduce another concept: the Dyson disk.
A Dyson disk is modeled as a large circular structure orbiting a star while maintaining a constant orientation toward it. The researchers describe the concept as a possible building block of a larger Dyson swarm.
Could a Dyson Disk Look Like a Planet?
One of the most interesting questions explored with Yuti is whether an artificial structure could produce a light curve that resembles a natural planet.
At first glance, a large circular object crossing a star could potentially create a transit similar to that of a planet.
However, the detailed shape of the light curve may contain differences.
The researchers investigate how the effects of stellar limb darkening and the geometry of the object influence the resulting signal. They also examine the signal-to-noise requirements that could be necessary for identifying possible Dyson-disk candidates.
This is important because an unusual light curve alone would not automatically prove the existence of alien technology.
Natural astronomical objects can also create complicated signals. Therefore, any potential technosignature would require careful analysis and follow-up observations to eliminate alternative explanations.
A New Tool for the Search
Yuti's importance lies in its flexibility.
Traditional models often focus on specific types of objects, while Yuti is designed as a more general framework capable of handling objects with virtually any geometry.
That could make it useful not only for SETI research, but also for studying unusual natural transit events.
The researchers plan to make the simulator publicly available, allowing other scientists to use it for modeling different astronomical systems and investigating unusual light curves.
For now, Yuti does not prove that alien megastructures exist. Instead, it provides something scientists need before they can confidently search for them: a way to understand what their possible signatures might look like.
As telescopes continue collecting increasingly precise measurements of distant stars, tools such as Yuti could help astronomers distinguish ordinary cosmic phenomena from genuinely unusual signals—and perhaps identify targets worthy of a closer look.
Reference: Ushasi Bhowmick, Vikram Khaire, "Yuti: A General-purpose Transit Simulator for Arbitrary Shaped Objects Orbiting Stars", The Astronomical Journal, Volume 168, Number 6, 2026. DOI 10.3847/1538-3881/ad7d8d
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