Giant-impact hypothesisThe giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact, suggests that the Moon was formed from the ejecta of a collision between the early Earth and a Mars-sized planet, approximately 4.5 billion years ago in the Hadean eon (about 20 to 100 million years after the Solar System coalesced). The colliding body is sometimes called Theia, named after the mythical Greek Titan who was the mother of Selene, the goddess of the Moon.
Impact eventAn impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, though atmospheres mitigate many surface impacts through atmospheric entry.
Impact winterAn impact winter is a hypothesized period of prolonged cold weather due to the impact of a large asteroid or comet on the Earth's surface. If an asteroid were to strike land or a shallow body of water, it would eject an enormous amount of dust, ash, and other material into the atmosphere, blocking the radiation from the Sun. This would cause the global temperature to decrease drastically. If an asteroid or comet with the diameter of about or more were to hit in a large deep body of water or explode before hitting the surface, there would still be an enormous amount of debris ejected into the atmosphere.
Fast-food restaurantA fast-food restaurant, also known as a quick-service restaurant (QSR) within the industry, is a specific type of restaurant that serves fast-food cuisine and has minimal table service. The food served in fast-food restaurants is typically part of a "meat-sweet diet", offered from a limited menu, cooked in bulk in advance and kept hot, finished and packaged to order, and usually available for take away, though seating may be provided.
RestaurantA restaurant is a business that prepares and serves food and drinks to customers. Meals are generally served and eaten on the premises, but many restaurants also offer take-out and food delivery services. Restaurants vary greatly in appearance and offerings, including a wide variety of cuisines and service models ranging from inexpensive fast-food restaurants and cafeterias to mid-priced family restaurants, to high-priced luxury establishments.
