Green comets are a type of comet that appear green in color due to the presence of diatomic carbon molecules in their coma, or atmosphere. These molecules absorb sunlight and emit green light, giving the comet its distinctive color. Green comets are relatively rare compared to other colors of comets, making them a unique and fascinating sight in the night sky. **

Yes, there are comets that can strike Earth more than once. Comets are celestial bodies that orbit the Sun, and some have orbits that intersect with Earth's orbit. If a comet's orbit brings it close enough to Earth multiple times, it is possible for the same comet to strike Earth more than once over a long period of time. However, the likelihood of a specific comet striking Earth multiple times is very low due to the vastness of space and the unpredictable nature of comet orbits. **

Comets can vary in size, but on average they are relatively small compared to other celestial bodies. Most comets have a nucleus that ranges from a few hundred meters to a few kilometers in diameter. However, they can also have a surrounding cloud of gas and dust called a coma, and a long tail that can extend for millions of kilometers. Overall, comets are relatively small compared to planets and moons. **

Comets can travel faster than Earth when they are approaching the Sun, as they are accelerated by the Sun's gravitational pull. However, as they move away from the Sun, their speed decreases. Overall, comets can have varying speeds depending on their distance from the Sun and their trajectory. Earth, on the other hand, orbits the Sun at a relatively constant speed of about 67,000 miles per hour. **

Yes, there are comets that can impact Earth more than once. This can happen if a comet's orbit brings it back into the inner solar system and on a collision course with Earth multiple times. However, the likelihood of a specific comet impacting Earth more than once is extremely low, given the vastness of space and the complexity of orbital dynamics. Additionally, the impact of a comet on Earth is a rare event in general. **

There is a hypothesis called panspermia which suggests that life on Earth may have been seeded by comets or meteorites carrying microorganisms from other parts of the universe. Some scientists believe that the organic compounds and water found in comets could have provided the building blocks for life on Earth. However, this hypothesis is still a topic of debate and has not been conclusively proven. Further research and evidence are needed to determine whether comets have indeed inoculated Earth with life. **

Larger comets are not necessarily slower than smaller ones. The speed of a comet is determined by various factors such as its distance from the sun, its size, and its trajectory. While larger comets may have more mass and gravitational pull affecting their speed, smaller comets can also travel at high speeds depending on their orbit and proximity to the sun. Ultimately, the speed of a comet is unique to each individual comet and cannot be generalized based solely on its size. **

Larger comets are not necessarily slower than smaller ones. The speed of a comet is determined by its distance from the Sun and its trajectory. Larger comets can have a wide range of speeds depending on these factors. Some larger comets may move faster than smaller ones, while others may move slower. Ultimately, the size of a comet does not directly correlate with its speed. **