Mysterious Interstellar Object Showing Signs of "Non-Gravitational Acceleration"

"In early July, astronomers spotted a mysterious object, later dubbed 3I/ATLAS after it was confirmed to be the third-ever interstellar visitor cruising through our solar system. Last week, the object, which is now generally believed to be a comet, reached its closest point to the Sun, or its perihelion, brightening up at an unexpected rate and turning " distinctly bluer." And it may be getting a major boost that's unaccounted for by the Sun's gravitational pull as well."

"As Harvard astronomer Avi Loeb laid out in a blog post last week, the acceleration is likely the result of 3I/ATLAS losing significant amounts of mass, forming an elongating plume of dust and gas. Put simply, as it expels this material at a greater rate, it's being kicked in the opposite direction. Loeb suggests the object could lose "about a tenth of its mass" in a matter of a single month."

"During an NBC News interview on Monday, Loeb explained that the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile observed a "deviation by four arcseconds in right ascension from the expected path." "And that's very significant statistically," he said, calculating the boost corresponding to the "evaporation of about a sixth of the mass of the object," which is a "significant fraction.""

3I/ATLAS is an interstellar object now believed to be a comet that brightened unusually and turned distinctly bluer near perihelion. The object exhibits measurable non-gravitational acceleration inconsistent with solar gravity alone. Observations indicate a deviation of about four arcseconds in right ascension from its expected path. The acceleration can be explained by substantial mass loss through outgassing and dust ejection, producing an elongating plume whose recoil provides thrust. Estimates suggest loss of roughly a tenth to a sixth of the object's mass over a short interval. A large surrounding gas and dust cloud should become detectable when the object reemerges from behind the Sun in November–December 2025.

Read at Futurism