Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms, Idioms, Wikipedia.


circular, bowl-shaped depression on the earth's surface. (For a discussion of lunar craters, see moonmoon,
natural satellite of a planet (see satellite, natural) or dwarf planet, in particular, the single natural satellite of the earth. The Earth-Moon System

The moon is the earth's nearest neighbor in space.
..... Click the link for more information.
.) Simple craters are bowl-shaped with a raised outer rim. Complex craters have a raised central peak surrounded by a trough and a fractured rim.

Many of the largest craters are formed by the impact of meteoritesmeteorite,
meteor that survives the intense heat of atmospheric friction and reaches the earth's surface. Because of the destructive effects of this friction, only the very largest meteors become meteorites.
..... Click the link for more information.
. Impacting at speeds in excess of 10 mi/sec (16 km/sec), a meteorite creates pressures on the order of millions of atmospheres, producing shock waves that blast out a circular hole and often destroy the meteorite. Meteor, or Barringer, Crater, near Winslow, Arizona, c. 3-4 mi (1 1-5 km) in diameter and 600 ft (180 m) deep, is probably the best-known crater of this type. Of the more than 160 impact craters identified on earth, the largest are at Manicouagan, Quebec; Vredefort, South Africa; and Chicxulub (off the coast of the Yucatán peninsula), Mexico. Others include the Chesapeake Bay impact crater, Virginia; Chubb Crater, Quebec; Lake Bosumtwi, Ghana; Brent Crater, Ontario; and Kebira, SW Egypt. Two sizable impact events occurred in the 20th cent., both in Siberia. In 1908 in the Tunguska BasinTunguska Basin,
c.400,000 sq mi (1,036,000 sq km), Krasnoyarsk Territory and Sakha Republic, E central Siberian Russia, between the Yenisei and Lena rivers. It has a huge untapped coal reserve.
..... Click the link for more information.
 near Lake Baykal one occurred that caused vast destruction of timber from its blast, and the other in 1947 at Sikhote-Alin also caused great damage. Craters that have been obliterated by erosion over thousands of years, leaving only a circular scar on the earth's surface, are called astroblemesastrobleme
, large, circular structure ranging from c. 1-2 mi to 40 mi (.8–64 km) in diameter. Astroblemes are found at numerous places on the earth's surface, e.g., Meteor, or Barringer, Crater in Arizona, Brent Crater in Ontario, and Vredefort Ring in South Africa.
..... Click the link for more information.
. The fractured rock of buried impact craters (e.g., Chicxulub) may become a trap for oil and natural gas.

Craters are also commonly formed at the surface opening, or vent, of erupting volcanoesvolcano,
vents or fissures in the earth's crust through which gases, molten rock, or lava, and solid fragments are discharged. Their study is called volcanology. The term volcano
..... Click the link for more information.
, particularly of the type called cinder cones, where the lava is extruded rather explosively. Virtually all volcanoes display a crater, called a sink, around the vent; this is believed to be a collapse feature caused by molten lava subsiding as an eruption phase diminishes. Volcanic craters formed in these ways are relatively small, usually less than 1 mi (1.6 km) in diameter, and represent only a small fraction of the cone's diameter at the base. A

caldera is a much larger crater, typically ranging from 3 to 18 mi (5–30 km) in diameter, and represents a considerable fraction of the volcano's basal diameter. In a few instances, however, tremendous volcanic eruptions have left calderas 50 mi (80 km) or so, such as that that forms much of Yellowstone National Park or the basin of Lake Toba, Sumatra, Indonesia. Most calderas are formed by the collapse of the central part of a cone during great eruptions. A few small calderas have been formed by explosive eruptions in which the top of a volcano was blown out. Some volcanic craters are created by a combination of these events. Formed thousands of years ago, the caldera that contains Crater Lake, Oreg., is 6 mi (9.7 km) in diameter. In recent times, caldera-producing eruptions occurred at Krakatoa, Indonesia, in 1883 and Katmai, Alaska, in 1912.

See also tektitetektite
, naturally occurring, silica-rich (65%–80% SiO2) glass resembling obsidian and sometimes shale, and is normally jet black to olive green. They appear as small rounded or elongated objects that often have aerodynamic shapes and range from a fraction of
..... Click the link for more information.


See P. Hodge, Meteorite Craters and Impact Structures of the Earth (1994).


(kray -ter) (Cup) A small inconspicuous constellation in the southern hemisphere near Leo, the brightest stars being of 3rd and 4th magnitude. Abbrev.: Crt; genitive form: Crateris; approx. position: RA 11.5h, dec –l5°; area: 282 sq deg.



a bowl- or funnel-shaped depression with a diameter measuring between dozens of meters and several kilometers and a depth from a few meters to hundreds of meters. Craters form during volcanic eruptions, as a result of the impact of meteorites, and as a result of large man-made explosions. Volcanic craters are usually located on the peaks or slopes of volcanoes. At the bottom of the crater are one or several vents through which lava and other volcanic products rising along an outlet channel from the magmatic center reach the surface. Sometimes the bottom of the crater is covered with a lake of lava or a small, newly formed volcanic cone.

The craters on the moon and Mars are round depressions surrounded by circular ridges; their diameters are up to 100–200 km and they are up to several kilometers deep. A distinction is made among them between craters formed during the impact of meteorites and asteroids and craters of volcanic origin (similar to the earth's volcanic craters and calderas).



(the Cup), a constellation of the southern hemisphere; its brightest star has a visual stellar magnitude of 3.6. The constellation is most easily viewed in March; it is visible from the central and southern regions of the USSR. (SeeSTELLAR SKY.)


A large, bowl-shaped topographic depression with steep sides.
A rimmed structure at the summit of a volcanic cone; the floor is equal to the vent diameter.
(mechanical engineering)
A depression in the face of a cutting tool worn down by chip contact.
A depression at the end of the weld head or under the electrode during welding.


A constellation, right ascension 11 hours, declination 15°S. Abbreviated Crt. Also known as Cup.


1. the bowl-shaped opening at the top or side of a volcano or top of a geyser through which lava and gases are emitted
2. a similarly shaped depression formed by the impact of a meteorite or exploding bomb
3. any of the circular or polygonal walled formations covering the surface of the moon and some other planets, formed probably either by volcanic action or by the impact of meteorites. They can have a diameter of up to 240 kilometres (150 miles) and a depth of 8900 metres (29 000 feet)
4. a large open bowl with two handles, used for mixing wines, esp in ancient Greece
References in classic literature ?
No fire was visible any where, but gusts of sulphurous steam issued silently and invisibly from a thousand little cracks and fissures in the crater, and were wafted to our noses with every breeze.
From his bed of suffering, the dying missionary could contemplate that fiery crater from which a thousand jets of dazzling flame were that moment escaping.
Bowen Tyler's manuscript had made it perfectly evident to all that the subterranean outlet of the Caspakian River was the only means of ingress or egress to the crater world beyond the impregnable cliffs.
Two miles beyond Crater Lake lay Happy Camp--so named because here was found the uppermost fringe of the timber line, where men might warm themselves by fire again.
When he had trussed Tarzan securely, Bukawai went back into the corridor, driving the hyenas ahead of him, and pulling across the opening a lattice of laced branches, which shut the pit from the cave during the night that Bukawai might sleep in security, for then the hyenas were penned in the crater that they might not sneak upon a sleeping Bukawai in the darkness.
1846; The Red Skins, 1846; The Crater (Marks Reef), 1847; Captain Spike, or the Islets of the Gulf, 1848; Jack Tier, or the Florida Reefs, 1848; The Oak Openings, or the Bee-Hunter, 1848; The Sea Lions,
But for that resolution so often recalled, Clennam might have wished him in the crater of Mount Etna, in return for this civility.
Rising in a volcanic region, amid extinguished craters, and mountains awful with the traces of ancient fires, it makes its way through great plains of lava and sandy deserts, penetrates vast sierras or mountainous chains, broken into romantic and often frightful precipices, and crowned with eternal snows; and at other times, careers through green and smiling meadows, and wide landscapes of Italian grace and beauty.
Our instruments enable us to perceive craters, with the inner cones so common to all our own volcanoes, giving reason to believe in the activity of innumerable burning hills at some remote period.
Some of the interior valleys are strewed with scoria and broken stones, evidently of volcanic origin; the surrounding rocks bear the like character, and vestiges of extinguished craters are to be seen on the elevated heights.
She appeared completely riddled with craters, and her essentially volcanic character was apparent at each observation.
They made good time down the chain of lakes which fills the craters of extinct volcanoes, and late that night pulled into the huge camp at the head of Lake Bennett, where thousands of goldseekers were building boats against the break-up of the ice in the spring.