The iron catastrophe was a postulated major
geological event
A geological event is a temporally and spatially heterogeneous and dynamic (diachronous) happening in Earth history that contributes to the transformation of Earth system and the formation of geological strata. Event stratigraphy was first propo ...
early in the
history of Earth
The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologi ...
, where heavy metals such as iron and nickel congregated in the core during a geologically brief period.
The original
accretion
Accretion may refer to:
Science
* Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity
* Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucl ...
of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's material into a spherical mass is thought to have resulted in a relatively uniform composition. While residual heat from the collision of the material that formed the Earth was significant, heating from
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
materials in this mass gradually increased the temperature until a critical condition was reached. As material became molten enough to allow movement, the denser
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
and
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
, evenly distributed throughout the mass, began to migrate to the center of the planet to form the core. The
gravitational potential energy
Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (conv ...
released by the sinking of the dense
NiFe globules, along with any cooler, denser solid material, is thought to have been a runaway process, increasing the temperature of the protoplanet above the melting point of most components, resulting in the rapid formation of a molten iron core covered by a deep global silicate
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
. This event, an important process of
planetary differentiation
In planetary science, planetary differentiation is the process by which the chemical elements of a planetary body accumulate in different areas of that body, due to their physical or chemical behavior (e.g. density and chemical affinities). The ...
, occurred at about 500 million years into the formation of the planet.
Formation of Earth's magnetosphere
This large spinning mass of super-hot metal is responsible for the creation of the
Earth's magnetic field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic f ...
, the
magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...
, which protects the Earth from
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
and the most harmful components of
solar radiation
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
Solar irradiance is measured in watts per square metre (W/m ...
coming from the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. The magnetosphere protects both
Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
and
life
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energ ...
to the present day and distinguishes the planet from its close celestial neighbour,
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
, which no longer has a significant magnetic field nor comparable atmosphere. The term ''catastrophe'' is, here, in the mathematical sense of "a large, sudden change or discontinuity", as contrasted with "a disaster", because this event was necessary for life to emerge and evolve on Earth: without it, Earth's atmosphere would have been, as on Mars, stripped away by solar wind long before the present epoch.
Another theory, however, suggests Mars did once experience its own iron catastrophe and was once shielded by a magnetosphere. By this theory Mars has simply cooled faster than the Earth, gradually solidifying its dynamic iron center, hence shutting down its magnetosphere. The finding of signs of liquid water once existing on Mars suggests that it once had its own magnetic shield to keep the water in the atmosphere of the planet from being blown into space by solar wind.
See also
*
Rain-out model
The rain-out model is a model of planetary science that describes the first stage of planetary differentiation and core formation. According to this model, a planetary body is assumed to be composed primarily of silicate minerals and NiFe (i.e. a ...
References
External links
Lecture// Columbia university, GEOLOGY V1001x
{{Geology-stub
Planetary science
Geological processes
Hadean