TektiteTektites () are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess (1867–1941), son of Eduard Suess. They generally range in size from millimetres to centimetres. Millimetre-scale tektites are known as microtektites.
ProtoplanetA protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other's orbits and collide, gradually coalescing into the dominant planets. A planetesimal is an object formed from dust, rock, and other materials, measuring from meters to hundreds of kilometers in size.
ChelyabinskChelyabinsk (Челя́бинск; Силәбе, Siläbe) is the administrative center and largest city of Chelyabinsk Oblast, Russia. It is the seventh-largest city in Russia, with a population of over 1.1 million people, and the second-largest city in the Ural Federal District, after Yekaterinburg. Chelyabinsk runs along the Miass River, and is just east of the Ural Mountains. The area of Chelyabinsk contained the ancient settlement of Arkaim, which belonged to the Sintashta culture.
Evolution of mammalsThe evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synapsid species that looked like mammals. The lineage leading to today's mammals split up in the Jurassic; synapsids from this period include Dryolestes, more closely related to extant placentals and marsupials than to monotremes, as well as Ambondro, more closely related to monotremes.
Manicouagan ReservoirManicouagan Reservoir (also Lake Manicouagan) is an annular lake in central Quebec, Canada, covering an area of . The lake island in its centre is known as René-Levasseur Island, and its highest point is Mount Babel. The structure was created 214 (±1) million years ago, in the Late Triassic, by the impact of a meteorite in diameter. The lake and island are clearly seen from space and are sometimes called the "eye of Quebec". The lake has a volume of .
Popigai impact structureThe Popigai impact structure is the eroded remnant of an impact crater in northern Siberia, Russia. It is tied with the Manicouagan structure as the fourth largest verified impact structure on Earth. A large bolide impact created the diameter crater approximately 35 million years ago during the late Eocene epoch (Priabonian stage). It might be linked to the Eocene–Oligocene extinction event. The structure is east from the outpost of Khatanga and northeast of the city of Norilsk, NNE of the Anabar Plateau.
Impact structureAn impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface expression of an impact structure. In many cases, on Earth, the impact crater has been destroyed by erosion, leaving only the deformed rock or sediment of the impact structure behind.
Minor Planet CenterThe Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids), calculating their orbits and publishing this information via the Minor Planet Circulars.
Global coolingGlobal cooling was a conjecture, especially during the 1970s, of imminent cooling of the Earth culminating in a period of extensive glaciation, due to the cooling effects of aerosols or orbital forcing. Some press reports in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced greenhouse effect. In the mid 1970s, the limited temperature series available suggested that the temperature had decreased for several decades up to then.
RheasilviaRheasilvia ˌri:@'sIlvi@ is the most prominent surface feature on the asteroid Vesta and is thought to be an impact crater. It is in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta, . However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of , making it one of the largest craters in the Solar System, and at 75°S latitude, covers most of the southern hemisphere.
