Saturn has at least 274 moons, more than any other planet in our solar system. (Image credit: dottedhippo via Getty Images)
If you look up at the starry sky on a clear night, the brightest and most visible object is probably the Moon. Unless you have a good telescope, it is the only natural satellite you can see with the naked eye. As a result, most people have a distorted idea of what the Moon is and how common natural satellites are.
In fact, there are a variety of natural satellites in our cosmic environment, ranging from jagged city-sized space rocks to large, rounded bodies that may be large enough to be classified as planets in their own right.
So how many moons in the solar system have we actually found? The answer, it turns out, depends on what you mean by moon.
The International Astronomical Union (IAU) officially recognizes 416 planetary moons orbiting eight worlds in the solar system, according to NASA. However, there are also 507 “small-body moons” — moons of asteroids and dwarf planets — listed by NASA’s Jet Propulsion Laboratory. If we add up the two types, as most astronomers do, the total number of natural satellites in the solar system rises to 923 (as of March 2025).
But that’s likely just the “tip of the iceberg,” Edward Ashton, an astronomer at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan, told Live Science in an email. Astronomers have discovered dozens of new planetary moons and small-body satellites in the past few years alone, and technological advances will likely speed up the pace at which they can find even more in the coming years, he added.
What is the moon?
“The simplest definition [of a moon] is that it's an object that orbits a larger, non-stellar body,” Ashton told Live Science. “But that's not really the whole answer.”
For example, there are currently thousands of artificial satellites orbiting the Earth that meet this definition, but are not considered moons because they are not natural. These spacecraft also have a limited lifespan before they fall back to Earth and burn up in the atmosphere.
Some natural satellites, such as quasi-moons and mini-moons, are also temporary and do not control orbits around planets.
A quasi-moon temporarily orbiting the sun near Earth may look like it is in orbit around our planet. But it is not.
Brett Gladman, an astronomer at the University of British Columbia
Sourse: www.livescience.com
