For months now, astronomers have been closely watching the mysterious interstellar object 3I/ATLAS as it rips through the solar system at a breakneck velocity.
And before it finally leaves us for good, the object — which is broadly believed to be a comet, in spite of other theories that we’ll get to in a minute — is expected to make its closest approach to Earth in just over a week from now, coming within just 167 million miles. While that’s still roughly 1.5 times the distance from the Earth to the Sun, nearby spacecraft are already making the most out of the opportunity.
NASA’s Hubble Space Telescope captured images of the unusual visitor on November 30 when it was just 178 million miles away, follow-up observations after the telescope spotted the object back in July. Using its Wide Field Camera 3 instrument, Hubble revealed 3I/ATLAS’ coma, the fuzzy atmosphere of ice and dust surrounding its nucleus, in the form of an ominous blue glow.
“3I/ATLAS will pass closest to Earth on December 19, 2025,” explained Harvard astronomer Avi Loeb, who has long championed the far-fetched theory that the object may be an alien spacecraft, on his blog. “Fortunately, this date coincides with a new Moon when the view of the sky will not be contaminated by moonlight, making it an ideal observing night for Earth-based telescopes.”
“My hope,” he added, “is that we will gain new insights into the nature of 3I/ATLAS at that time thanks to data from hundreds of observatories, including the Hubble and Webb space telescopes.”
Even after its closest pass to Earth, astronomers will continue observing the unusual visitor.
“Observations are expected to continue for several more months as 3I/ATLAS heads out of the solar system,” NASA noted on its website.
Separate observations by the European Space Agency’s Jupiter Icy Moons Explorer (JUICE) spacecraft last month also revealed surprising amounts of activity as it was being heated up by the Sun, losing mass in the form of sublimating ices.
ESA scientists are expecting most of the data collected by its spacecraft’s scientific instruments to arrive in late February.
Besides making its closest approach to Earth, 3I/ATLAS is also expected to pass by Jupiter in the spring of next year, yet another tantalizing opportunity to examine only the third interstellar object cruising through our solar system ever to be identified in history using NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS), a network of ground-based telescopes.
Another intriguing theory: that objects like 3I/ATLAS may have once brought life to Earth billions of years ago, a theory known as “panspermia.”
Recent observations by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile found significant amounts of both gaseous methanol and hydrogen cyanide, important precursors for the formation of life.
Scientists also suggest it may have come from a different planetary system that’s much older than our own, a tantalizing possibility that “gives me goosebumps to think about, frankly,” as NASA lead scientist for solar system small bodies Tom Statler told reporters during a briefing last month.
More on 3I/ATLAS: 3I/ATLAS Is Carrying Ingredients for Life, NASA Finds