"An impact event is a collision between astronomical objects causing measurable effects."
The study of how impact events have affected the geology and evolution of planets and their moons.
Meteorites: Study of meteorites and their composition can provide insight into the formation of impact craters.
Planetary Surfaces: Understanding the appearance and composition of planetary surfaces is essential to studying impact craters.
Terrestrial/Celestial Mechanics: Understanding the dynamics of celestial bodies, such as their orbits and trajectories, can help in understanding how impact craters form.
Shock Waves: Study of shock waves produced by high-velocity collisions can help in understanding how impact craters form.
Crater Morphology: Study of the shape of impact craters and the processes that shape them.
Geology of Impact Craters: Exploration of the internal geology of impact craters can help in understanding their formation and evolution.
Ejecta: Study of the fragments and debris that are ejected during an impact event.
Impact Melting: Study of the melting and transformation of rocks due to the extreme heat produced during an impact event.
Tectonics: Understanding the movement and deformation of the earth's lithosphere can help in understanding the formation and evolution of impact craters.
Impact Hydrology: Understanding the effects of impact craters on water distribution, runoff, and groundwater can help in understanding the evolution of impact craters.
Impact-Induced Volcanism: Study of volcanism resulting from the deformation and melting of rocks caused by impact events.
Paleogeography: Study of the geography and climate of the earth during the time period when impact events occurred.
Astrobiology: Exploration of the potential for impact craters to serve as habitats for extraterrestrial life.
Remote Sensing: Techniques for mapping and observing planetary surfaces from a distance.
Mathematical Modeling: The use of mathematical models to simulate and predict the formation and evolution of impact craters.
Impact Hazards: Exploration of the potential hazards posed by impact events and strategies for mitigating those hazards.
Simple Craters: Simple craters represent the simplest form of impact structures caused by small asteroids or comets. They are formed by nearly vertical impacts at low velocities and result in a bowl-shaped depression, with a circular rim and a flat floor.
Complex Craters: Complex craters result from larger and more energetic impacts, and they are characterized by a central uplift surrounded by a raised rim. They often have a terraced appearance and a more complex morphology than simple craters.
Peak Ring Craters: Peak ring craters are a type of complex crater with a central peak ring or multiple rings that surround the central uplift. They are formed by high-energy impacts that cause the rocks underneath the crater to melt and flow, resulting in a distinctive ring of mountains in the center of the crater.
Multi-Ring Basins: Multi-ring basins are the largest and most complex impact structures in the solar system. They are formed by massive objects that hit planets or moons at high velocities and create concentric rings of mountains and valleys around the central depression. Examples include the Moon's Orientale Basin and Mars's Hellas Basin.
Cryptovolcanic Structures: Cryptovolcanic structures are impact craters that are partially or completely filled with volcanic material. They are formed when the impact melts the subsurface rocks, creating magma that is ejected to the surface, filling the crater cavity. They are characterized by their flat or low-lying floors and a lack of central uplifts.
Rampart Craters: Rampart craters are a type of complex crater with an outer, terraced rim and a flat floor. They are formed by oblique impacts that cause the crater ejecta to pile up on one side of the crater, creating a rampart-like structure.
Dark Halo Craters: Dark halo craters are formed when the impact melts the surface rocks and creates a thin, dark layer of glassy material around the rim and ejecta. They are usually found on icy bodies like comets, where the dark halo is created by exposure of the underlying dark rock or organic compounds.
"Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids."
"When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences."
"Atmospheres mitigate many surface impacts through atmospheric entry."
"Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale."
"Impact events appear to have played a significant role in the evolution of the Solar System since its formation."
"Major impact events have significantly shaped Earth's history."
"Impact events have been implicated in the formation of the Earth–Moon system."
"Impact events also appear to have played a significant role in the evolutionary history of life."
"Impacts may have helped deliver the building blocks for life (the panspermia theory relies on this premise)."
"Impacts have been suggested as the origin of water on Earth."
"The prehistoric Chicxulub impact, 66 million years ago, is believed to not only be the cause of the Cretaceous–Paleogene extinction event but acceleration of the evolution of mammals leading to their dominance."
"Throughout recorded history, hundreds of Earth impacts (and exploding bolides) have been reported, with some occurrences causing deaths, injuries, property damage, or other significant localised consequences."
"One of the best-known recorded events in modern times was the Tunguska event, which occurred in Siberia, Russia, in 1908."
"The 2013 Chelyabinsk meteor event is the only known such incident in modern times to result in numerous injuries. Its meteor is the largest recorded object to have encountered the Earth since the Tunguska event."
"The Comet Shoemaker–Levy 9 impact provided the first direct observation of an extraterrestrial collision of Solar System objects, when the comet broke apart and collided with Jupiter in July 1994."
"An extrasolar impact was observed in 2013 when a massive terrestrial planet impact was detected around the star ID8 in the star cluster NGC 2547 by NASA's Spitzer Space Telescope and confirmed by ground observations."
"In April 2018, the B612 Foundation reported: 'It's 100 percent certain we'll be hit [by a devastating asteroid], but we're not 100 percent certain when.'"
"Physicist Stephen Hawking considered in his final book Brief Answers to the Big Questions that an asteroid collision was the biggest threat to the planet."
"In June 2018, the US National Science and Technology Council warned that America is unprepared for an asteroid impact event, and has developed and released the 'National Near-Earth Object Preparedness Strategy Action Plan' to better prepare."