In solar physics, a spicule, also known as a fibril or mottle,[a] is a dynamic jet of plasma in the Sun's chromosphere about 300 km in diameter.[1] They move upwards with speeds between 15 and 110 km/s from the photosphere and last a few minutes each[1] before falling back to the solar atmosphere.[2] They were discovered in 1877 by Angelo Secchi, but the physical mechanism that generates them is still hotly debated.
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