We are obsessed with aliens lurking in the cosmos, even though we have no idea if they actually exist. Finding extraterrestrial life has been a major goal for scientists dating back centuries, and the search for intelligent aliens remains a topic of intense public fascination and speculation.
Now, a well-funded alien-hunting project has published a free online version of the Exotica Catalog, an immense catalog of 737 known astronomical targets that includes “one of everything” in the universe, according to the document.
The project is the newest brainchild of Breakthrough Listen, the largest ongoing research program devoted to spotting potential “technosignatures,” which are signals that might be produced by a technologically advanced alien species and are detectable from Earth.
The Exotica Catalog was assembled by researchers led by Brian Lacki, an astrophysicist at the University of California Berkeley, with the goal of cataloging “one of everything” in the universe “to ensure that we are not missing some obvious technosignatures,” according to the document. The comprehensive list compiles one of every type of known object and phenomena in the universe—from comets to galactic cores to fast radio bursts—into a 76-page guide.
“As far as we are aware, this is the first object list in recent times with the purpose of spanning the breadth of astrophysics,” the team said in the catalog. “We share it with the community in hopes that it can guide treasury surveys and as a general reference work.”
The motivation behind this huge target list is to “accelerate serendipity” in the search for extraterrestrial intelligence (SETI) by expanding “the diversity of objects” that could be potential sources of technosignatures, Lacki and his co-authors wrote.
“Serendipity is a key ingredient in the discovery of most new types of phenomena and extraordinary new objects,” the team said in the new work. “Although the simplest resolution may be that we are alone in the local universe, and others question whether we should expect to have detected technosignatures yet, many have suggested that ETIs are actually abundant but we are simply looking in the wrong places for them.”
In other words, Breakthrough Listen wants to inspire scientists who are conducting searches for smart aliens to consider the full spectrum of, well, weird space stuff out there. While it makes sense to prioritize observations of the most tantalizing targets, such as potentially habitable exoplanets—especially those that seem similar to Earth—the team recommends that scientists consider the possibility of aliens occupying “non-Earthy” environments as well.
“Speculations about exotic habitats in the literature include: life living on habitable icy worlds around red giants, inside large carbonaceous asteroids, in Kuiper Belts, inside rogue planets, or in the atmospheres of gas giants and brown dwarfs,” Lacki and his colleagues note in the catalog.
“Exotic life may be based on alternate biochemistries,” the team continued. “Intelligence does not need to be native to unusual habitats, as some locations may draw [extraterrestrial intelligences] from their homeworlds for reasons of energy collection, curiosity, or isolation.”
To that point, the huge index of the Exotica Catalog is organized into four main groups: Prototypes, Superlatives, Anomalies, and Controls.
The Prototype section is the “one of everything” section that collects all observed astronomical phenomena, with the exception of events that are too transient and mysterious to explain. The section is by far the largest chunk of the database and includes all the known subcategories of each object, meaning the various types of stars, planets, galaxies, and more.
The Superlative section, meanwhile, outlines the most extreme objects ever observed: Think the hottest known planets, the most energetic galaxy cores, or the fastest-spinning stars.
The Anomaly section compiles targets that are known to exist, but still remain mysterious on enigmatic levels. Examples include ’Oumuamua, the first interstellar object known to visit our solar system, or KIC 8462852, a star with a strange dimming pattern that inspired speculation about alien megastructures.
Last, the Control section contains objects that were once thought to be tantalizing anomalies, but have since turned out to have more banal explanations, such as technical issues with observational equipment. The idea is to include control samples to better anticipate false positives of technosignatures in the future.
Even if you are not an avid believer in intelligent aliens, the catalog makes for an interesting read based on the astounding variation and abundance of astronomical objects compiled in one place. Though it is intended to help scientists keep an open mind about potential sources of technosignatures, it is also an impressive record of humanity’s observational achievements over the past several millennia.
“We hope that the Exotica Catalog will prove useful to other efforts, both within SETI and outside it, in characterizing the whole panoply of objects in the known Universe,” Lacki’s team concluded.