* Technically: Anything orbiting the Sun that isn't a planet, dwarf planet, or comet can be considered an asteroid. This means you could have asteroid-sized objects as small as a pebble.
* Practicality: We mostly study asteroids larger than 1 meter (3 feet) across. This is because smaller objects are harder to detect and track, and they pose less of a threat to Earth.
* Different Categories: Within the "practical" range, there are categories:
* Meteoroids: These are smaller than 1 meter, and they become meteors (shooting stars) when they enter the Earth's atmosphere.
* Near-Earth Objects (NEOs): These asteroids have orbits that bring them relatively close to Earth. While some NEOs are small, others can be quite large.
The smallest asteroid ever observed: The smallest confirmed asteroid, discovered in 2021, is estimated to be just 1 meter across.
In essence, there's a spectrum of sizes. While a pebble in space could technically be an asteroid, the vast majority of those we study are significantly larger. The exact size of a specific asteroid depends on how it's categorized and its relevance to our understanding of space.
