How big are asteroids?
See the relative sizes of 22 asteroids in this video from MetaBallStudio. Asteroids range from human-scale 2008 TC3, which exploded in midair over the Sudan in 2008, to the enormous, spherical dwarf planet Ceres, largest object in the asteroid belt between Mars and Jupiter.
The first 10 objects shown in the video are near-Earth objects, some designated as potentially hazardous. The rest reside far away from Earth, mostly in the asteroid belt.
On October 12, 2021, ESO released a new video about the 42 largest objects in the main asteroid belt.
Earth-crossing asteroids are space objects whose orbits cross that of Earth. Of course, Earth is most likely far away in its orbit from the spot where they cross. Here is a list of Earth-crossing minor planets.
How many known near-Earth objects are there? Thousands, mostly very small. This chart shows how many have been discovered between 1980 and 2021.
Bottom line: See how big 22 asteroids are in comparison to New York City.
Asteroid Watch at NASA
Read more about NEOs at Center for Near-Earth Object Studies