WASHINGTON, Jan 20, 2026, 08:01 EST
- Data from NASA’s SPHEREx telescope show that interstellar comet 3I/ATLAS is releasing increased amounts of gas and dust following its close pass by the Sun.
- The comet hits opposition on Jan. 22, which means observers on the ground get a longer window to follow it through the night.
- Scientists confirm this is the third interstellar object spotted in the solar system, and it’s already on its way out.
NASA’s SPHEREx space telescope detected that interstellar comet 3I/ATLAS has entered a noticeably more active phase following its closest approach to the Sun, called perihelion. Carey Lisse from Johns Hopkins University Applied Physics Laboratory called it “a much more active object.” (Sci.News: Breaking Science News)
The timing is crucial because this visitor ranks among the rarest targets astronomers have tracked. NASA notes that 3I/ATLAS is only the third confirmed interstellar object spotted in our solar system, following 1I/‘Oumuamua and 2I/Borisov. It’s moving on a hyperbolic trajectory—too fast for the Sun’s gravity to capture. NASA confirms it posed no threat to Earth, passing about 1.8 astronomical units away on Dec. 19, and it’s expected to swing past Jupiter in March as it heads out. (NASA Science)
Italy’s Virtual Telescope Project plans a live online observing session on Jan. 22, starting at 23:30 UTC, after clouds disrupted their final broadcast set for Jan. 16. Opposition happens when an object lies roughly opposite the Sun in Earth’s sky, which usually means longer night-time visibility, though 3I/ATLAS is still faint. (The Virtual Telescope Project 2.0)
In a paper posted on the arXiv preprint server, Lisse and colleagues detailed SPHEREx’s observations of 3I/ATLAS between Dec. 8 and Dec. 15. They captured infrared data spanning 0.75 to 5 microns, detecting emissions from cyanide, water, organic molecules, carbon dioxide, and carbon monoxide. The team noted the water-gas signal was roughly 20 times stronger than previous SPHEREx data, with carbon monoxide flux increasing by a similar margin. Interestingly, dust and organics appeared pear-shaped, whereas most gas features showed up as round in the images. They described this as a preliminary analysis, with a more comprehensive study planned before SPHEREx returns to the region in April. (arXiv)
The comet has stirred plenty of debate since its discovery, but back in November NASA officials found no evidence pointing to an artificial source. “It looks and behaves like a comet,” said NASA associate administrator Amit Kshatriya. Meanwhile, Oxford astrophysicist Chris Lintott dismissed the alien spacecraft theory as “simply nonsense.” (Reuters)
3I/ATLAS first came to light on July 1, 2025, thanks to a Chile-based telescope that’s part of the ATLAS network—a NASA-backed survey hunting for potentially hazardous objects. “Many efforts [are] underway to observe this object,” University of Hawaii astronomer Larry Denneau, an ATLAS co-lead, told Reuters at the time. (Reuters)
The observation window isn’t on our side. The comet’s already retreating, and ground-based sightings risk being wiped out by clouds, moonlight, or simply a target that dims quicker than expected.
Scientists care even about brief bursts of activity because they reveal how an interstellar comet behaves once it crosses the solar system’s “ice line”—where sunlight vaporizes water ice. The next reliable glimpse will likely come from space telescopes, not backyard scopes.
