As our cosmic neighborhood gears up for the visit of the interstellar object 3I/ATLAS in October 2025, it’s an exciting moment to explore its unique gravitational properties.
To get a better grasp of gravity, we can look at escape velocity, which is the speed needed to break free from an object’s gravitational pull. For example, the Moon’s escape speed is about 2.4 kilometers per second, which is a lot faster than a speeding bullet but still much slower than light. In contrast, black holes have escape speeds that surpass light itself. Once something crosses their boundary, it can’t return.
3I/ATLAS, by comparison, is a solid object. Its escape speed depends on its size. A recent study suggests that 3I/ATLAS is at least 5 kilometers wide but could be as big as 46 kilometers. This implies it has an escape speed somewhere between 1.3 and 12 meters per second. To visualize that, the world record for the 100-meter dash is 9.58 seconds, set by Usain Bolt in 2009. He ran at about 10.44 meters per second—fast enough to escape the gravitational grip of a 40-kilometer-wide asteroid. So, if Bolt ran on a smaller asteroid than 3I/ATLAS, he could potentially launch into space!
Interestingly, 3I/ATLAS rotates about every 16.16 hours. Its rotation speed is only about 0.25 to 2.5 meters per second, which is significantly below its potential escape speed. This means it likely won’t break apart like a comet would; its gravity holds it together. Still, gravity isn’t uniform—smaller solid objects are held together by chemical connections, unlike larger celestial bodies held by gravity.
Despite weighing over 33 billion tons, the gravity of 3I/ATLAS is surprisingly weak. When it passed by Mars, it moved at a staggering speed of 67 kilometers per second without significantly affecting the planet’s motion. Its gravitational impact was minuscule—akin to just a tiny fraction of Usain Bolt’s record speed.
3I/ATLAS captures the public’s imagination not just for its mass but because of the mystery surrounding it. People are drawn to its story and the science behind it. Social media is already buzzing with discussions about its upcoming visit, reflecting a growing interest in cosmic phenomena.
As we await 3I/ATLAS’s arrival, this interstellar object emphasizes our continuous curiosity about the universe. It serves as a reminder of the wonders of space and the complexity of gravity, drawing attention far beyond its size.
For a deeper dive into the science of escape velocity and gravitational effects, you can explore reputable resources like NASA’s Gravity Basics, which further explain these fascinating concepts.
