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Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 19% of Earth's radius [0.7% of volume] or 70% of the Moon 's radius. [32][33] The inner core was discovered in 1936 by Inge Lehmann and is generally composed primarily of iron and some nickel.
Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 20% of Earth’s radius or 70% of the Moon's radius. [1] [2] There are no samples of Earth's core accessible for direct measurement, as there are for Earth's mantle. [3]
Lithosphere–asthenosphere boundary. A diagram of the internal structure of Earth. The lithosphere consists of the crust and upper solid mantle (). The green dashed line marks the LAB. The lithosphere–asthenosphere boundary (referred to as the LAB by geophysicists) represents a mechanical difference between layers in Earth's inner structure.
One promising model proposed in 2023 described an inner core that in the past had spun faster than Earth itself, but was now spinning slower. For a while, the scientists reported, the core’s ...
Earth orbits the Sun, making Earth the third-closest planet to the Sun and part of the inner Solar System. Earth's average orbital distance is about 150 million km (93 million mi), which is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon.
The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron–nickel outer core, at a depth of 2,891 km (1,796 mi) below Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle ...
t. e. Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') [1] is the scientific theory that Earth 's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. [2][3][4] The model builds on the concept of continental ...
Map showing Earth's principal tectonic plates and their boundaries in detail. These plates comprise the bulk of the continents and the Pacific Ocean.For purposes of this list, a major plate is any plate with an area greater than 20 million km 2 (7.7 million sq mi)