Here's why:

* Small: Asteroids are generally much smaller than planets.

* Dense: They are made up of rock and metal, making them denser than comets.

* Circles the Sun: Asteroids orbit the Sun in a similar way to planets.

However, there are other possibilities, depending on the size and composition of the object:

* Comet: While comets are generally less dense than asteroids, they can also orbit the Sun.

* Dwarf Planet: Dwarf planets are smaller than planets but larger than asteroids. Some dwarf planets orbit the Sun.

* Meteoroid: These are small rocky or metallic objects that orbit the Sun. They are smaller than asteroids.

To know for sure what the object is, we would need more information about its size, composition, and orbital path.