The matter and particles expelled by an erupting volcano are collectively known as ejecta.
Expel is a term used to describe material expelled in a sudden event. In medical terms, ejection can be used to refer to abnormal bodily fluids such as vomit, although it is much more commonly used in the scientific community. Volcanology, geology, and astrophysics use ejecta to determine information about present or past events.
In volcanology, the term refers to the particles and matter expelled by an erupting volcano. The substance can be composed of many different materials, including partially liquid magma and rock. Volcanic ejecta is sometimes classified by sample size; Extremely thin samples are called ash, samples less than 2.5 inches (63.5 mm) in diameter are called lapilli, and anything larger is called a block or bomb, depending on the solidity of the sample. Collectively, the volcanic ejecta is often referred to as tephra.
In astrophysics, ejection helps scientists study supernovae.
The study of tephra can help volcanologists in several ways. In addition to providing data on the composition and condition of the volcano itself, some scientists hope to improve volcano warning systems and technology by studying the trajectory and velocity of volcanic tephra. By collecting data from active volcanoes, computer modeling programs can be developed to improve human understanding of how a volcano would act in an eruption.
Ejection is an important area of study when considering impact craters on Earth, the Moon, and other celestial bodies.
Ejection is also an important area of study when considering impact craters on Earth, the Moon, and other celestial bodies. When the impact of a meteorite or other object falling on a land mass creates a crater, a layer of debris of various materials forms around the rim of the crater. This layer, called the ejecta blanket, may be one of the main targets of scientific study. By analyzing these blankets on Earth, scientists gain important information about the collapsing body and its chemical composition. On human missions to Mars and the Moon, spacecraft study and sample debris layers in impact craters to help better understand planetary composition, as well as learn about the origin of the crater.
In astrophysics, the term has yet another meaning, indicating a sudden and violent event. When a star explodes, material is flung away from the source and into space. This powerful form of ejection helps scientists identify supernovae, since the layer of blown material is often visible to exploration teams. Any discovered stellar ejecta material could be of great importance for scientific discovery, as the chemical components can carry important information about the elemental composition of stars billions of light-years away.