- 4145 - OLDEST METEORITE - older than the Earth? - Scientists have analyzed one of the oldest space rocks ever discovered. The data could reveal secrets about the solar system in its infancy during the birth of the planets and also help scientists better determine the ages of the oldest meteorites that fall to Earth.
-------------- 4145 - OLDEST METEORITE - older than the Earth?
- 4.6 billion-year-old meteorite could reveal
how Earth formed different layers. The
meteorite “Erg Chech 002” found in the Sahara desert in 2020 is one of the
oldest known space rocks.
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- The 4.6-billion-year-old Erg Chech 002
meteorite, which is encrusted with green crystals, was discovered in the Erg
Chech region of the Sahara Desert in Algeria in 2020. Meteorites like this are believed to have
formed from material in a disk of gas and dust around the infant sun.
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- Cold, dense patches of this "solar
nebula" collapsed to birth the planets, but leftover material formed
comets and asteroids from which meteors break away, often finding their way to
the surface of Earth in the form of meteorites. This means that meteorites can
paint a picture of the elements that served as the building blocks of the
planets.
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- Erg Chech 002 contained the radioactive
isotope Aluminum-26 when it formed, which is significant because this unstable
form of Aluminum is believed to have been important in a later stage of Earth's
evolution, called "planetary melting.
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- Planetary melting is believed to be the
process by which rocky planets like ours "differentiated" or formed
different compositions at different layers. This is because the melting allows
denser material to sink to the core of planets. For Earth, an example of this
differentiation would be the formation of a dense metal core and, above it, a
less dense rocky mantle.
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- Understanding how Aluminum-26 was
distributed as the planets were forming around 4.6 billion years ago is
important to building a picture of how the rocky inner planets of the solar
system evolved. Because Aluminum-26
decays to Magnesium-26, a stable form of Magnesium, it can be used as a dating
system for space rocks.
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- To determine the age of Erg Chech 002 as
4.566 billion years old, the team
measured the amounts of lead isotopes within it. The half-life of Aluminum-26 is around
717,000 years, meaning it is too short-lived to be directly found in large
quantities in the 4.6-million-year-old space rock. But, when it decays, this
radioactive isotope of Aluminum leaves behind Magnesium-26, a stable
non-radioactive isotope of Magnesium.
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- That means Magnesium-26 can be used to
determine the starting amount of Aluminum-26 in a space rock like Erg Chech
002, and this could be used as a dating system (also known as a chronometer)
for space rocks.
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- The Aluminum-26 – Magnesium-26 decay system
also serves as a high-resolution relative chronomete. It is important to determine if Aluminum-26
was unevenly or evenly distributed throughout the solar nebula that birthed the
planets, asteroids, and comets of the solar system.
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- Developing a generalized approach for
isotopic dating with Aluminum-26 – Magnesium-26 and other extinct isotope
chronometers that accounts for heterogeneous distribution of the parent
radionuclide would allow us to produce more accurate and reliable age data for
meteorites and asteroidal and planetary materials to advance a better
understanding for the formation of our solar system.
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September 9, 2023 OLDEST
METEORITE - older than the Earth? 4145
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