i do not know :D
Hale-Bopp comet had a nucleus estimated to be about 18 to 40 kilometers in diameter, making it one of the largest observed comets of the 20th century.
Anywhere from the size of pebbles (1 cm) to gigantic rocks that rival some of the moons of other planets for size (1000 km diameter)
they belived that comets are small and big
comets
They range from a diameter of 100m to 40+ kilometers
It is not exactly a sphere, the longest axis is 15km and the shortest one is 8km.
Comets are generally fairly large, dozens or hundreds of miles in diameter. Small compared to planets or asteroids, but large compared to meteors or dust.
Comets are created in the Oort cloud. The Oort cloud is a big circle of ice and dust surrounding our solar system.
Although comets appear very large when they are near the Sun because of the large dust cloud that follows behind them, they are actually the smallest of the objects listed. Comets typically have a diameter of less than 6 miles, which is much smaller than the typical diameter of the other objects listed above.
Twelve inches is a length. It can be a diameter, but if it is a diameter, you would simply say 'The circle is 12 inches diameter'. So; how big is it - it is 12 inches.
Meteoroids are smaller than both comets and asteroids. They are small rocky or metallic objects that are typically smaller than asteroids and comets, which are large bodies that can range in size from several meters to hundreds of kilometers in diameter.
It is a diameter of 39.37 cm.