The weight of a comet varies greatly depending on its size and composition. Comets are primarily composed of ice and dust, with some rocky material. The largest known comets, such as Hale-Bopp, can have a mass of up to 10^16 kg, which is about the mass of a small mountain. However, most comets are much smaller, and have a mass of less than 10^12 kg.

The density of a comet is also highly variable, but is typically around 0.5 g/cm³. This means that a comet with a mass of 10^16 kg would have a volume of about 2 x 10^16 cm³, or about 200 cubic kilometers.

The weight of a comet is also affected by its distance from the Sun. As a comet approaches the Sun, its ice begins to melt and vaporize, which causes the comet to lose mass. This process continues until the comet reaches its closest point to the Sun, at which point it may lose up to 90% of its original mass.

Overall, the weight of a comet is determined by its size, composition, and distance from the Sun.