Astronomers from around the world are monitoring the trajectory of A11pl3Z, a celestial object that could have originated outside the Solar System and is currently crossing the planetary neighbourhood of Earth, the European Space Agency (ESA) reported Wednesday.
This body, described by specialists as harmless, is located near Jupiter, hundreds of millions of miles from Earth, and is heading towards Mars’ orbit. According to the agency, its route will not bring it closer to the Sun beyond the Martian orbit.
The phenomenon is, if confirmed, the third time an object of interstellar origin has been recorded in our Solar System. The first case was detected in 2017, when Oumuamua was discovered, named after a Hawaiian term meaning “explorer,” following its discovery by an observatory in Hawaii. The second confirmed interstellar visitor is 2l/Borisov, observed in 2019 and classified as a comet.
The new object has been identified thanks to observations initially made by NASA’s ATLAS system in Hawaii on Tuesday, U.S. astronomer David Rankin said. Since then, both professionals and amateurs have collaborated in the analysis of previous telescope data, tracking its movement until June 14.
According to Richard Moissl, ESA’s head of planetary defense, A11pl3Z travels at more than 60 kilometers per second, a speed that exceeds that of asteroids or comets originating within the solar system.
According to Moissl, this speed and trajectory mean that it does not orbit around our Sun, but comes from interstellar space and will return there. The object is estimated to be between 10 and 20 kilometers in diameter, although it could be smaller if it is composed mainly of ice, a material that reflects more light.
Astrophysicist Josep Trigo-Rodríguez, of the Barcelona Space Science Institute, pointed out that the object could reach 40 kilometers (25 miles) in diameter. For now, its exact nature is unknown — whether it is a rocky asteroid or an icy comet — as well as its precise shape, pending new observations.
NASA noted that it maintains active monitoring of A11pl3Z, while official confirmation of its interstellar origin must come from the Minor Planet Center of the International Astronomical Union, an institution that has already recorded more than 100 observations of the phenomenon
Enthusiasm among scientists is notable because of the potential to study material from other star systems. Mark Norris, an astronomer at the University of Central Lancashire in the UK, said the object moves faster than Oumuamua and 2I/Borisov. Norris also indicated that the object is at a distance comparable to that of Jupiter from Earth and that its current observation is only possible in the southern hemisphere.
Recent models, cited by Norris, suggest there could be up to 10,000 interstellar objects wandering the solar system at any time, although most would be significantly smaller than A11pl3Z. If these calculations are confirmed, the Vera C. Rubin Observatory in Chile, which will start operations soon, could identify new interstellar visitors monthly.
Moissl added that it is currently not feasible to arrange a mission to intercept A11pl3Z. However, these occasional visitors give the scientific community the opportunity to directly analyze material from outside the solar system, which which could shed light on the potential for life-friendly conditions in other star systems, especially if precursors such as amino acids were detected on the surface of one of these bodies.
International attention remains on the trajectory of A11pl3Z, whose approach to the Sun will take place in October, continuing to be observable via telescopes until next year. The new observations will be key to determining their composition and confirming their interstellar provenance, an event of great relevance to contemporary astronomy.