Astronomers discover 3I/ATLAS — third interstellar object to visit our Solar System

Astronomers have confirmed the discovery of 3I/ATLAS (also known as C/2025 N1 or A11pl3Z), marking it as the third known interstellar object to enter our Solar System—after 1I/ʻOumuamua (2017) and 2I/Borisov (2019) . --- 🚀 Key Facts about 3I/ATLAS Discovery: First spotted by the NASA-funded ATLAS survey (Rio Hurtado, Chile) on July 1, 2025; pre-discovery images from June 14 were found in ATLAS and ZTF archives . Speed & Orbit: Traveling at approximately 60–68 km/s, on a steep hyperbolic trajectory . Eccentricity around 6.1, highest of any interstellar visitor so far . Current Position: Roughly 4.5 AU (≈670 million km) from the Sun, inside Jupiter’s orbit . Structure: Shows signs of cometary activity—a faint coma and a short tail—so it’s classified as an interstellar comet . Size Estimate: Preliminary brightness suggests a core a few kilometers across, though some estimates have reached up to ~20 km if assumed reflective like an asteroid—cometary activity likely skews this . Perihelion (Closest Sun Approach): Late October (~Oct 29–30), reaching ~1.35–1.4 AU—just inside Mars’s orbit . Proximity to Earth: Will remain at least 1.6 AU from Earth (≈240 million km) . Closest Earth approach around 19 December 2025, approximately 270 million km away . Visibility: Too faint for naked-eye viewing, but accessible with moderate amateur telescopes now through September, with a livestream from the Virtual Telescope Project on July 3 . --- 🧠 Why It Matters Rarity and Insight: Only the third interstellar object ever detected—its discovery confirms these visitors may be more common than once thought . Comparative Science: Studying its composition and activity offers clues about how planetary systems form—and whether they share traits with ours . Future Opportunities: Enhanced sky surveys (e.g., Vera C. Rubin Observatory) and missions like ESA’s Comet Interceptor could intercept similar objects in the future . --- 🗓️ Observation Schedule Date Range Key Event Now – Sept 2025 Ground-based telescope visibility October 29–30, 2025 Perihelion (closest to Sun, inside Mars’s orbit) Dec 19, 2025 Nearest Earth pass (~270 million km) Mar 2026 Exits past Jupiter, leaving Solar System Earth’s position during October perihelion places us on the opposite side of the Sun, reducing optimal observation—best views will be later into December . --- 🔭 Watching the Interstellar Visitor Visual tracking: Through telescopes (150–200 mm aperture), guided by emerging orbital charts. Online viewing: Catch the livestream from Virtual Telescope Project and Space.com on July 3 . --- This discovery represents a thrilling step forward in astroscience—each interstellar visitor is a time capsule from another star. As telescopes get sharper and surveys wider, we’ll likely see many more. Let me know if you'd like orbital path visuals, observing tips, or follow-up on its scientific study!