The largest one is called Ceres and it is about 933 kilometers across. All other known asteroids are less than 340 km in diameter. When comets approach the sun, they begin to warm and melt. Evaporating gases and dust that sputter off the surface of a comet create long tails that can sometimes be seen from Earth. Comet dust forms a cloud of debris that trails the comet in its orbit around the sun.
Comets are about the same size as the smaller asteroids.
The Leonid meteors in November appear to come from the direction of this constellation. The Leonid meteors are caused by debris from comet Tempel-Tuttle. The Perseid meteors are caused by debris from comet Swift-Tuttle. The Perseid meteors in August appear to come from the direction of this constellation. All meteor showers have their own radiant.