3I/ATLAS Brightens Dramatically as it Swings Past the Sun

Interstellar comet 3I/ATLAS has undergone dramatic brightening as it approached its closest point to the Sun. Researchers have been using solar monitoring satellites to track it during a period when Earth based observations were impossible due to the comet’s position behind the Sun. Analysis of data from STEREO-A, SOHO, and GOES-19 spacecraft revealed the comet brightened at an unexpectedly rapid rate between mid September and late October 2025, with its light showing a distinctly blue colour indicating significant gas emission rather than just reflected sunlight from dust. The comet’s unusual behaviour and the cause of its steep brightening remain mysteries that ground based observers will now investigate as it emerges into dark skies.