Earth has a second quasi-moon — a small asteroid that has been orbiting us for 100 years
Some trivia is so bizarre it forces you to rethink your entire understanding of the world. Check out the fact below, see how others reacted, and scroll down to dive into the verified science and history behind it.
Asteroid Cruithne (about 5km wide) has been in a complex resonant orbit with Earth for approximately 100 years, co-orbiting the Sun in a way that traces a horseshoe pattern relative to Earth over a 770-year cycle. It is not gravitationally bound to Earth like the Moon, so it's called a 'quasi-moon' or 'co-orbital asteroid'. Several other small objects share similar relationships with Earth. At some point in the distant future, gravitational perturbations will eject Cruithne from this relationship — but for now, Earth has more than one companion in orbit.
We're taught Earth has one moon, full stop. Finding that 'moon' is actually a simplified answer — and that Earth has multiple gravitational companions in various types of co-orbital relationships — makes the solar system feel more complex than the textbook diagram suggests.
The Science Behind It
Asteroid Cruithne (about 5km wide) has been in a complex resonant orbit with Earth for approximately 100 years, co-orbiting the Sun in a way that traces a horseshoe pattern relative to Earth over a 770-year cycle. It is not gravitationally bound to Earth like the Moon, so it's called a 'quasi-moon' or 'co-orbital asteroid'. Several other small objects share similar relationships with Earth. At some point in the distant future, gravitational perturbations will eject Cruithne from this relationship — but for now, Earth has more than one companion in orbit.
Why Your Brain Finds This Hard to Believe
Sources & Verification
OddlyHuman Editors
VerifiedWritten and fact-checked by the OddlyHuman Behavioral Science Team. We verify all psychological, sociological, and historical claims against peer-reviewed journals, primary sources, and established encyclopedias to bring you accurate insights.
Read our Editorial Guidelines →“Earth has a second quasi-moon — asteroid Cruithne, 5km wide, has been in a complex resonant orbit with us for ~100 years. Not gravitationally bound like our Moon, but a companion nonetheless. 🌍 #OddlyHuman”