In 2017, ‘Oumuamua stunned scientists as the interstellar object entered and then exited the solar system, something previously unprecedented in the world of astronomy. In 2019, the comet Borisov was deemed the second interstellar object to enter our solar system. However, in 2022, another object was found to have previously come into our solar system and struck earth, without notice, in 2014. These three are the only known interstellar objects to have entered our solar system in recorded human history.
But now a fourth and much larger object has been spotted entering the solar system, and the scientific community is rushing to study what, exactly, this thing is.
While these findings are subject to change as more data becomes available, the object, dubbed A11pl3Z, is quite large. According to a Medium article by Harvard astronomer Avi Loeb, A11pl3X’s H-magnitude of 12, previously listed by NASA, suggests a diameter of about 20 kilometers. Recent adjustments to the H-magnitude, now listed at 13.6, indicate that it may be even larger.
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Another interpretation of the data, according to Loeb, could suggest that A11pl3Z is smaller than these estimates, but a plume of gas and dust are creating the illusion of a much larger object.
This simulation of A11pl3Z’s trajectory, created by amateur astronomer Tony Dunn, shows its likely path in relation to the sun and planets:
According to Dunn’s projected trajectory, the object is expected to pass quite far from Earth but inside Mars’ orbit, measuring 2.4 times as far from Earth as Earth’s distance from the Sun when it reaches its closest point on Dec. 17 of this year.
Marshall Eubanks, physicist and co-founder of Space Initiatives, commented on the object’s speed to the The Minor Planet Mailing List, writing “next April (2026) it will have a velocity relative to Earth of ~ 90 km/s. That should set a record.”
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Eubanks added that the object may be visible from the Mars Reconnaissance Orbiter when it passes “relatively close to Mars” in October.
The Minor Planet Mailing List hosts public discourse as a service to the astronomical community, and is, according to its website, “populated with many of the world’s best amateur astronomers as well as many professional astronomers involved in all facets of asteroid and comet research.”
Large Unidentified Object Detected Entering Our Solar System first appeared on Men’s Journal on Jul 2, 2025
