--- title: "How many moons are there in the solar system? about 900 confir" description: "about 900 confirmed, and the number keeps moving How the figure is estimated, how confident it is, and what makes the scale graspable." url: https://atoneplace.net/how-many/moons-in-the-solar-system/ site: "At One Place" --- # How many moons are there in the solar system? **How many moons are there in the solar system?: about 900 confirmed, and the number keeps moving** Ganymede and Titan are each larger than the planet Mercury. Meanwhile most of Saturn's 274 moons are smaller than a large town. Roughly 900 moons are confirmed, of which about 420 orbit the eight planets and the rest orbit dwarf planets and asteroids. Saturn overtook Jupiter decisively in 2025 when a single survey added 128 new moons at once, taking it to 274 against Jupiter's 95. Almost all of the new ones are irregular satellites a few kilometres across — captured objects on distant, tilted, often retrograde orbits, not the round bodies people picture. Earth has one; Mercury and Venus have none. ## How the figure is arrived at Take many long exposures of the space around a planet while tracking at the planet's rate, then stack the images so that a faint moving object builds up signal while the streaked background stars do not. Confirming a moon requires recovering it on later nights to prove the orbit is bound, which is why announcements come in batches years after the discovery images. ## How confident it is - **Low estimate:** 850 - **High estimate:** 950 - **Spread:** 1.1× between the bounds ## Other space and the universe counts - [How many stars are there in the universe?](https://atoneplace.net/how-many/stars-in-the-universe/) — about 200 billion trillion - [How many stars are there in the Milky Way?](https://atoneplace.net/how-many/stars-in-the-milky-way/) — between 100 billion and 400 billion - [How many atoms are there in the universe?](https://atoneplace.net/how-many/atoms-in-the-universe/) — about 10^80 - [How many galaxies are there?](https://atoneplace.net/how-many/galaxies-in-the-universe/) — hundreds of billions — possibly 2 trillion - [How many satellites are in orbit?](https://atoneplace.net/how-many/satellites-in-orbit/) — about 12,000 active satellites - [How many planets are there in the galaxy?](https://atoneplace.net/how-many/planets-in-the-milky-way/) — at least 100 billion — probably more planets than stars - [How many stars can you see with the naked eye?](https://atoneplace.net/how-many/stars-visible-to-the-naked-eye/) — about 9,000 over the whole sky; roughly 2,500 at once - [How many constellations are there?](https://atoneplace.net/how-many/constellations/) — exactly 88 - [How much space junk is there?](https://atoneplace.net/how-many/space-debris/) — about 40,000 tracked objects, and over 130 million fragments too small to track - [How many asteroids are there?](https://atoneplace.net/how-many/known-asteroids/) — about 1.4 million catalogued ## Common questions ### How many moons are there in the solar system? about 900 confirmed, and the number keeps moving ### How is that estimated? Take many long exposures of the space around a planet while tracking at the planet's rate, then stack the images so that a faint moving object builds up signal while the streaked background stars do not. Confirming a moon requires recovering it on later nights to prove the orbit is bound, which is why announcements come in batches years after the discovery images. ## Related pages - [How many stars are there in the universe?](https://atoneplace.net/how-many/stars-in-the-universe/) - [How many stars are there in the Milky Way?](https://atoneplace.net/how-many/stars-in-the-milky-way/) - [How many atoms are there in the universe?](https://atoneplace.net/how-many/atoms-in-the-universe/) - [How many galaxies are there?](https://atoneplace.net/how-many/galaxies-in-the-universe/) - [How many satellites are in orbit?](https://atoneplace.net/how-many/satellites-in-orbit/) - [How many planets are there in the galaxy?](https://atoneplace.net/how-many/planets-in-the-milky-way/) - [How many stars can you see with the naked eye?](https://atoneplace.net/how-many/stars-visible-to-the-naked-eye/) - [How many constellations are there?](https://atoneplace.net/how-many/constellations/) - [How many people are there in the world?](https://atoneplace.net/how-many/people-alive-right-now/) - [How many countries are there in the world?](https://atoneplace.net/how-many/countries/) - [How many bones are in the human body?](https://atoneplace.net/how-many/bones-in-the-human-body/) - [How many grains of sand are there on Earth?](https://atoneplace.net/how-many/grains-of-sand-on-earth/) - [How many ants are there in the world?](https://atoneplace.net/how-many/ants-on-earth/) - [How many trees are there in the world?](https://atoneplace.net/how-many/trees-on-earth/) ## Sources - NASA — National Aeronautics and Space Administration (https://www.nasa.gov/) [Public domain (US Government)]