Interstellar Comet 3I Atlas, the third known visitor from another star system, makes its closest Earth approach this week – glowing green and sparking “alien” theories worldwide.
Astronomers are buzzing as Interstellar Comet 3I Atlas swings by Earth on December 19, 2025, at a safe 167 million miles – closer than Mars but far enough to pose no threat. Discovered in July 2025 by the ATLAS telescope in Chile, this rare interstellar comet 3I Atlas has captivated scientists and skywatchers alike with its unusual trajectory, composition, and dramatic color change from red to vibrant green.
The 3I Atlas is only the third confirmed interstellar object to visit our solar system, following 1I/’Oumuamua (2017) and 2I/Borisov (2019). Its hyperbolic orbit – speeding at 58 km/s – confirms it originated from beyond our Sun’s gravitational pull, likely ejected from another star system billions of years ago. “This is a messenger from deep space,” said Dr. Karen Meech of NASA’s Hubble team, which captured stunning images showing the comet’s 500,000 km anti-tail pointing toward the Sun.
Discovery and Journey of Interstellar Comet 3I Atlas
Interstellar Comet 3I Atlas was first spotted on July 1, 2025, as a faint object moving oddly fast. Initial observations revealed its non-gravitational acceleration – a hallmark of comets outgassing – but its path screamed “interstellar.” By October 29, it reached perihelion (closest to Sun) at 1.36 AU, heating up and releasing gases that turned it emerald green from diatomic carbon (C2) emissions.
New images from ESA’s XMM-Newton X-ray observatory (December 3) and Hubble show the 3I Atlas growing brighter and more active. Its coma expanded dramatically, and the green hue intensified – perfect for viewing during the new moon on December 19. “It’s putting on a show as it leaves forever,” said astronomer Quanzhi Ye.
How to See Interstellar Comet 3I Atlas
The closest approach on December 19 offers prime viewing:
- Best Time: Evening sky after sunset, low in the southwest (Northern Hemisphere).
- Visibility: Magnitude ~8-9 – needs binoculars or small telescope.
- Location Tips: Dark skies away from city lights; use apps like Stellarium to find it near Venus.
- Live Streams: NASA and Virtual Telescope Project host free views.
Southern Hemisphere observers get better looks as Interstellar Comet 3I Atlas heads outbound.
The “Alien” Theories Surrounding 3I Atlas
Harvard’s Avi Loeb reignited speculation: “Its acceleration and composition could suggest artificial origin – like a lightsail fragment.” But most experts dismiss this. “Natural outgassing explains everything,” counters NASA’s Davide Farnocchia. The 3I Atlas is carbon-rich with low water ice – typical for distant births.
Scientific Goldmine: What Interstellar Comet 3I Atlas Reveals
As the brightest interstellar comet yet, 3I Atlas offers unprecedented data:
- Composition: High CO2, low H2O – hints at formation in a cold exoplanet system.
- Age: Possibly 7-14 billion years old.
- Future: JWST observations planned for 2026 tail analysis.
“This visitor tells stories of other stars,” said ESA’s Colin Snodgrass.
Why Interstellar Comet 3I Atlas Matters
Only three confirmed interstellar objects in history make each precious. 3I Atlas helps map galactic chemistry and planet formation elsewhere. As it fades into deep space, never to return, it reminds us: we’re not alone in receiving cosmic wanderers.
Catch 3I Atlas this week – a once-in-a-lifetime celestial event.
Know more..
Trump Jr. Proposes to Bettina Anderson at White House Bash!
