How many asteroids are there?
The Minor Planet Center catalogue holds roughly 1.4 million asteroids with orbits good enough to be numbered or designated, of which about 38,000 are near-Earth asteroids. That is the count of known objects, not existing ones: the main belt is thought to contain perhaps 1 to 2 million asteroids larger than 1 km and many millions more below that. Surveys have found an estimated 95% of near-Earth asteroids larger than 1 km — the ones that would be globally catastrophic — but well under half of those in the 140 m range that could destroy a city.
How the figure is arrived at
Automated sky surveys photograph the same field repeatedly; software finds points of light that move against the fixed stars. Three or more nights of observations fix an orbit well enough for a provisional designation, and observations at a later opposition confirm it well enough for a permanent number.
How confident it is
- Low estimate
- 1,300,000
- High estimate
- 1,500,000
- Spread
- 1.2× between the bounds
The catalogue grows by tens of thousands a year as surveys such as Pan-STARRS and the Vera Rubin Observatory come up to speed. Figure as of 2025.
Other space and the universe counts
- How many stars are there in the universe? about 200 billion trillion
- How many stars are there in the Milky Way? between 100 billion and 400 billion
- How many atoms are there in the universe? about 10^80
- How many galaxies are there? hundreds of billions — possibly 2 trillion
- How many satellites are in orbit? about 12,000 active satellites
- How many moons are there in the solar system? about 900 confirmed, and the number keeps moving
- How many planets are there in the galaxy? at least 100 billion — probably more planets than stars
- How many stars can you see with the naked eye? about 9,000 over the whole sky; roughly 2,500 at once
- How many constellations are there? exactly 88
- How much space junk is there? about 40,000 tracked objects, and over 130 million fragments too small to track
Common questions
- How many asteroids are there?
- about 1.4 million catalogued
- How is that estimated?
- Automated sky surveys photograph the same field repeatedly; software finds points of light that move against the fixed stars. Three or more nights of observations fix an orbit well enough for a provisional designation, and observations at a later opposition confirm it well enough for a permanent number.
Related pages
- How many stars are there in the universe? about 200 billion trillion
- How many stars are there in the Milky Way? between 100 billion and 400 billion
- How many atoms are there in the universe? about 10^80
- How many galaxies are there? hundreds of billions — possibly 2 trillion
- How many satellites are in orbit? about 12,000 active satellites
- How many moons are there in the solar system? about 900 confirmed, and the number keeps moving
- How many planets are there in the galaxy? at least 100 billion — probably more planets than stars
- How many stars can you see with the naked eye? about 9,000 over the whole sky; roughly 2,500 at once
- How many people are there in the world? Living things and the natural world
- How many countries are there in the world? Things people built
- How many bones are in the human body? The human body
- How many grains of sand are there on Earth? Living things and the natural world
- How many ants are there in the world? Living things and the natural world
- How many trees are there in the world? Living things and the natural world
Sources
- NASA — National Aeronautics and Space Administration (Public domain (US Government))