Fastest comet ever recorded spewed 70 Olympic pools’ worth of water daily
Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. Astronomers knew 3I/ATLAS wasn’t a local comet not long after first spotting it in July 2025. As only the third interstellar object ever detected in our solar system, it offered researchers a rare—and brief—opportunity. With the right timing and equipment, scientists around the world could examine a cosmic visitor who possibly formed under far different conditions than those experienced in our own region of the galaxy. 3I/ATLAS is now sailing away from Earth and our solar system itself, but astronomers have already learned a wealth of information. The fastest comet ever recorded is covered in ice volcanoes, and emits a dusty trail of methanol and cyanide in its wake. Earlier this month, the European Space Agency confirmed that 3I/ATLAS is also spewing the equivalent of 70 Olympic swimming pools’ worth of water every day. However, the exact type of water isn’t often seen here on Earth.According to astronomers at the University of Michigan (UM), the hydrogen in the comet’s …


