Comet 3I/ATLAS, the third interstellar object ever discovered, will pass closest to Earth overnight between Thursday and Friday, December 18–19. While the rare visitor from another star system poses no threat to Earth, it offers astronomers and skywatchers a unique chance to observe an object that originated beyond our solar system.
At its closest point, the comet will be approximately 168 million miles (270 million kilometers) away from Earth. The exact moment of closest approach is expected at 1 a.m. EST (0600 GMT) on December 19, according to Space.com. Although this distance is still nearly twice as far away as the Sun—making dramatic close-up images unlikely—it remains a scientifically significant and rare event.
Comet 3I/ATLAS was first discovered in July 2025 and follows the earlier detections of 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019. The comet is now traveling away from the Sun and will eventually exit the solar system, making this period one of the last good opportunities to observe it.
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How to Watch Comet 3I/ATLAS Online
For most people, the best and easiest way to view the comet will be through a live online broadcast. The Virtual Telescope Project in Manciano, Italy, will host a free livestream on YouTube, beginning at 11 p.m. EST on December 18 (0400 GMT on December 19). The webcast will also remain available for replay after the live event concludes.
Viewing the Comet Through Telescopes
Skywatchers equipped with GoTo or smart telescopes may also be able to observe comet 3I/ATLAS directly. The comet is currently located in the constellation Leo, and motorized telescopes can automatically track it. Smart telescope users—such as those with the Seestar S50, Unistellar eVscope 2, Vaonis Vespera Pro, or Celestron Origin—should be able to locate the comet through their telescope control apps.
Using a planetarium app can also help identify its position in the sky. While the comet is technically visible with large astronomy binoculars, its faint brightness—around magnitude 11—means it will likely appear as a dim, slightly blurred point of light.
Best Equipment for Clearer Views
According to NASA, a medium-to-large telescope with an aperture of around 12 inches offers a better chance of spotting the comet. Through such instruments, observers may see a faint, fuzzy glow with a subtle greenish tint near the bright star Regulus in Leo, along with the nearby, dimmer star Rho Leonis.
Ongoing Observations
Astronomers on Earth and in space will continue to study comet 3I/ATLAS even after its close approach. Recently, NASA released new ultraviolet images captured by the Europa Clipper spacecraft, which observed the comet from a distance of about 102 million miles (164 million kilometers)—significantly closer than Earth’s vantage point. Additional images and data are expected to be released in the coming days.
As Comet 3I/ATLAS makes its closest pass by Earth, it offers a rare and fascinating reminder of how dynamic and interconnected our universe truly is. Whether you catch it through a telescope, follow its path using a sky app, or watch it via an online livestream, this interstellar visitor provides a unique opportunity to witness a piece of cosmic history. With astronomers continuing to monitor and study the comet, the coming days may reveal even more insights—making this close approach a moment worth watching and remembering.
