🌅 The Largest and Fastest Interstellar Object Ever

SOURCE

Taylor & Seligman (2025)

WHAT TO KNOW

• The largest and fastest interstellar object ever discovered is currently zooming through our solar system at 130,000 miles per hour (210,000 kilometers per hour), while spewing 88 pounds (40 kilograms) of water per second (about the same amount of water coming out of a fire hose at full blast). Current data also suggests comet 3I/ATLAS is about 3.5 miles wide (5.6 kilometers) and could be the oldest comet ever observed, potentially predating our 4.6-billion-year-old solar system by around 3 billion years.

WHY IT MATTERS

• 3I/ATLAS is just the third interstellar object ever recorded (though astronomers believe many slip by unnoticed), following the discoveries of 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019. 3I/ATLAS—which won’t strike the Earth—is moving twice as fast as both of its predecessors and, if its estimated size is confirmed, would be around 100 times larger than ʻOumuamua and 10 times larger than Borisov.

CONNECT THE DOTS

• Interstellar objects are those that originate outside of our solar system and fly through without falling into a stable orbit around the Sun. Scientists say observing the water coming off 3I/ATLAS is like “reading a note” from another planetary system and suggests the building blocks of life aren’t unique to our own. While scientists are still working out where exactly the comet came from, astronomers know it’s approaching from the general direction of the constellation Sagittarius, i.e., from the central region of our Milky Way galaxy.