* Astronomy

Blobrana · L

RE: Earth's magnetic field

Blobrana · L

"Spacequakes" Discovered in Earth's Upper Atmosphere

The sun can dump enough energy into Earth's magnetic field to trigger "spacequakes" in our planet's upper atmosphere, a new study has found.
The space weather phenomenon - technically a strong vibration in the planet's magnetic field - can affect auroras and can spawn "space twisters" capable of bringing down power lines.
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Blobrana · L

Earth's magnetic field is 3.45 billion years old

Scientists in the US have discovered that Earth's magnetic field, which protects all life on the planet, is 3.45 billion years old.
The evidence is seen in tiny iron minerals that are aligned inside ancient dacite rocks from the Barberton mountains in South Africa.
Analysis of minerals, however, indicates that the strength of the field was much weaker than today.
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Blobrana · L

Rocks record early magnetic field

Scientists have managed to push back the date for the earliest known presence of a magnetic field on Earth by about 250 million years.
The evidence is seen in tiny iron minerals that are aligned inside ancient dacite rocks from the Barberton mountains in South Africa.
Analysis of the 3.45-billion-year-old minerals indicates the strength the field was much weaker than today.
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Blobrana · L

Magnetised Rocks Push Back Origin of Earth's Magnetic Field

Earth's robust magnetic field protects the planet and its inhabitants from the full brunt of the solar wind, a torrent of charged particles that on less shielded planets such as Venus and Mars has over the ages stripped away water reserves and degraded their upper atmospheres. Unravelling the timeline for the emergence of that magnetic field and the mechanism that generates it--a dynamo of convective fluid in Earth's outer core--can help constrain the early history of the planet, including the interplay of geologic, atmospheric and astronomical processes that rendered the world habitable.
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Blobrana · L

Princeton paleomagnetists put controversy to rest
Princeton University scientists have shown that, in ancient times, the Earth's magnetic field was structured like the two-pole model of today, suggesting that the methods geoscientists use to reconstruct the geography of early land masses on the globe are accurate. The findings may lead to a better understanding of historical continental movement, which relates to changes in climate.
By taking a closer look at the 1.1 billion-year-old volcanic rocks on the north shore of Lake Superior, the researchers have found that Earth's ancient magnetic field was a geocentric axial dipole -- essentially a large bar magnet centred in the core and aligned with the Earth's spin axis.
Some earlier studies of these rocks had led other teams to conclude that the magnetic field of the ancient Earth had a far more complex structure -- some proposing the influence of four or even eight poles -- implying that present models of the supercontinents that relied on paleomagnetic data and an axial dipole assumption were wrong.

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Blobrana · L

Earth's magnetic field, long thought to be generated by molten metals swirling around its core, may instead be produced by ocean currents, according to controversial new research published this week.
It suggests that the movements of such volumes of salt water around the world have been seriously underestimated by scientists as a source of magnetism.
If proven, the research would revolutionise geophysics, the study of the Earths physical properties and behaviour, in which the idea that magnetism originates in a molten core is a central tenet.

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Blobrana · L

Earth's magnetic field perturbed by 'electric oceans', claims researcher
In a radical rethink of accepted geophysics, new research in the US links variations in the Earth's magnetic field with the ebb and flow of the world's oceans. Given the practical importance of these field variations in navigation and atmospheric modelling, the implications of this new research extend far beyond academia. However, the idea has already faced strong criticism from some researchers in the geophysics community.
The origin and mechanism of the Earth's magnetic field are amongst the biggest unsolved questions in the earth sciences. Most geophysicists agree however that the main component of the field - which defines the magnetic poles - is a dipole generated by the convection of molten iron deep within the Earth's interior.

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