Interstellar Comet 3I/ATLAS Enters Solar Conjunction Ahead of Perihelion
Discovery and trajectory
The ATLAS survey reported the object on July 1. Designated 3I/ATLAS, it follows a hyperbolic trajectory that will carry it back into interstellar space, making it the third confirmed interstellar visitor after 1I/ʻOumuamua and 2I/Borisov.
Solar conjunction and observing limitations
From Earth, 3I/ATLAS entered solar conjunction on October 21 and will pass its closest point to the Sun (perihelion) on October 29. While the object is near the Sun in the sky, ground‑based telescopes cannot observe it.
Spacecraft and orbiters elsewhere in the inner solar system — including platforms operating near Mars — could provide observations during the close approach. Available viewing angles, however, constrain which instruments can be used and what measurements are feasible at perihelion.
Artificial‑origin hypothesis and the Oberth‑maneuver scenario
A small number of researchers have proposed a remote possibility that the object might be artificial. One suggested scenario envisions a larger vehicle releasing smaller probes that perform a close‑Sun burn or gravitational assist (an Oberth maneuver) to alter their outbound trajectories.
Order‑of‑magnitude estimates cited in that context point to a characteristic radial change on the order of 0.36 astronomical units and a perihelion speed near 68 km/s. Those values are used to estimate the change in angular momentum per unit mass and the propulsive effort probes would need to achieve such trajectory adjustments.
Post‑perihelion observations and scientific outlook
Measurements taken after perihelion — especially high‑precision tracking of velocity and trajectory and searches for sudden shifts in mass distribution — will be critical for testing competing explanations. Until those post‑perihelion data are collected and analyzed, the working interpretation is that 3I/ATLAS is a natural cometary body.
