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. **

Some hidden gems in London include the Leighton House Museum, a beautifully preserved Victorian home with stunning Middle Eastern-inspired interiors, and the Hampstead Heath Pergola and Hill Garden, a tranquil and picturesque spot with stunning views of the city. Another hidden gem is the Little Venice area, a peaceful canal network with charming houseboats and waterside cafes. Additionally, the Sir John Soane's Museum, a unique house museum filled with an eclectic collection of art and antiquities, is a must-visit for history and architecture enthusiasts. **

Hidden gems like Kemono Jihen are lesser-known anime series that offer a unique and captivating story, compelling characters, and stunning animation. These hidden gems often fly under the radar but have a dedicated fanbase due to their high-quality storytelling and production. Kemono Jihen, in particular, stands out for its blend of supernatural elements, mystery, and character development, making it a must-watch for fans of the genre. These hidden gems often provide a refreshing and memorable viewing experience for anime enthusiasts looking for something new and different. **

Some short anime hidden gems include "Barakamon," a heartwarming slice-of-life series about a calligrapher finding inspiration in a rural village; "Tatami Galaxy," a unique and visually stunning show about a college student's surreal experiences; and "Anohana: The Flower We Saw That Day," a touching story about a group of friends dealing with grief and guilt. These anime may not be as well-known as some others, but they offer compelling stories and memorable characters that make them worth watching. **

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. **