Interstellar Comet 3I/ATLAS Approaches Jupiter for a Rare Gravitational Encounter Before Exiting the Solar System

Interstellar comet 3I/ATLAS nears Jupiter's Hill radius. Discover how this massive gravitational event will change the comet's exit from our solar system.

By: AXL Media

Published: Feb 28, 2026, 7:36 AM EST

A Final Encounter Before Solar Exit

The interstellar visitor known as 3I/ATLAS is reaching the final stages of its journey through our planetary neighborhood. After billions of years traversing the galaxy, the comet is preparing for a significant interaction with Jupiter, the most massive planet in our system. Having already passed its closest points to the Sun, Earth, and Mars, the object is now positioned to undergo a potential course correction driven by Jupiter’s immense mass. According to James Felton, the comet’s previous solar approach caused dramatic physical changes, including a substantial release of organic molecules and water, whereas its interactions with smaller rocky planets were less transformative.

Navigating the Jovian Hill Radius

On March 16, 2026, 3I/ATLAS will pass within 0.35832 astronomical units of Jupiter, a distance that brings it remarkably close to the gas giant’s Hill radius. The Hill radius defines the specific region where a massive body’s gravity exerts more influence over a smaller object than the Sun does. For Jupiter, this boundary sits at approximately 0.355 astronomical units, or 53 million kilometers. Researchers at the China National Space Administration and other international bodies have noted that entering this zone will subject the comet to significant gravitational perturbations that could redefine its exit path from the Solar System.

The Role of Non-Gravitational Acceleration

While gravity is the primary force at play, the ultimate trajectory of 3I/ATLAS also depends on non-gravitational factors. These include outgassing, where heating causes the release of trapped gases, and radiation pressure exerted by the Sun. A preprint study recently published to the arXiv server explains that the impact of the Jovian encounter is highly sensitive to the comet’s internal acceleration. According to the research team, major orbital shifts are most likely when non-gravitational acceleration reaches a specific threshold, while lower levels of activity may result in negligible changes to the comet's long-term parameters.