The term mass extinction (or extinction event)
refers to a relatively short period in the history of Earth
when many species went extinct. These are of astrophysical
interest in investigating possible astrophysical
causes such as impacts or solar events
(gamma-ray bursts, i.e., GRBs from relatively nearby progenitors
have also been proposed,
but if that occurred, evidence may well be scant).
Mass extinctions from geological events
can be of interest regarding the study of other
bodies
(solar systemplanets and moons and extra-solar planets),
regarding astrobiology and their habitability, given
the possibility that such events occurred on the body.
There are more than twenty very clear Earth events, such as the
one associated with the disappearance of dinosaurs,
and in a few cases an asteroid impact is suspected.
Details of how impacts caused extinction are a subject
of study. In addition to the impact location itself,
major tsunami are possible, forest/vegetation fires possibly
at great distances, and disruptions of the atmosphere, potentially
lasting years.