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Interstellar Comet 3I/ATLAS Slips From View as New Mass Claim and Solar Blast Focus Watch

Ground observations pause for solar glare, with spacecraft tracking plus new analyses probing its size, composition, and behavior.

Overview

  • 3I/ATLAS is becoming unobservable from Earth this week ahead of a late‑November return, with perihelion in late October at roughly 130 million miles from the Sun.
  • A new analysis led by Avi Loeb reports an inferred mass above 33 billion tons and a nucleus larger than several kilometers, far exceeding earlier estimates.
  • NASA and multiple teams continue to characterize the visitor as a natural, CO2‑rich comet on a safe trajectory, with its closest Earth distance expected in December at about 167 million miles.
  • A late‑September coronal mass ejection struck the object, and scientists are monitoring for any tail changes or subtle trajectory effects seen in past comet–CME encounters.
  • As it passes near Mars this week, ESA’s Mars Express and ExoMars TGO and NASA’s Mars Reconnaissance Orbiter plan imaging attempts, including HiRISE, to refine size constraints.