Comet 3I/ATLAS: Interstellar object speeding through solar system at 137,000 mph
A rare interstellar comet is flying through our solar system. Here's how—and when—you might be able to see Comet ATLAS from your backyard.
This animation shows the observations of comet 3I/ATLAS when it was discovered on July 1, 2025. The NASA-funded ATLAS survey telescope in Chile first reported that the comet originated from interstellar space. (Credit: ATLAS/University of Hawaii/NASA)
Astronomers are buzzing over a new discovery: a comet from beyond our solar system that could soon be visible through amateur telescopes. The object, officially named Comet 3I/ATLAS, was discovered on July 1, 2025, and is only the third-known interstellar object to pass through our cosmic neighborhood.
Its arrival offers scientists a rare opportunity to study a visitor from another star system, and gives skywatchers a chance to glimpse something truly out of this world.
Where did Comet ATLAS come from?
Comet 3I/ATLAS originated outside of our solar system, making it an interstellar object—a classification reserved for space rocks that aren't gravitationally bound to the sun.
Astronomers determined its unusual trajectory using data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Rio Hurtado, Chile. Its steep path through the inner solar system suggests it came from deep interstellar space.
This diagram shows the trajectory of interstellar comet 3I/ATLAS as it passes through the solar system. It will make its closest approach to the Sun in October. (NASA/JPL-Caltech)
Will Comet ATLAS hit Earth?
Despite its dramatic entrance, Comet ATLAS poses no threat to our planet. “Although the trajectory of the object brings it into the inner solar system, it won’t come close to Earth,” NASA explained.
Its closest approach will be about 170 million miles away, which is nearly 1.8 times the distance between Earth and the sun, or 700 times farther than the moon.
Will Comet ATLAS be visible in the night sky?
Right now, the comet is only visible with large, professional-grade telescopes, but that may change in the coming months as it moves closer to the inner solar system. While it's unlikely to become bright enough for the naked eye, predicting the brightness of comets can be tricky. Some fizzle, while others flare up.
“3I/ATLAS should remain visible to ground-based telescopes through September,” NASA said. “After that, it will pass too close to the sun to observe. It’s expected to reappear on the other side by early December, allowing for renewed observations.”
If it brightens more than expected, Comet ATLAS could become a highlight for amateur astronomers this winter. Even if it never becomes bright enough to see with the naked eye, folks with a telescope might be able to spot it from their backyards.
How fast is Comet ATLAS moving?
This interstellar visitor is flying through space at breakneck speed. As of early July, Comet ATLAS was traveling at 137,000 mph, more than twice the speed of Earth’s orbit around the sun, which is about 67,000 mph.
It will continue to accelerate as it approaches the sun before slingshotting back into deep space, never to return.
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