Solar spicule

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.

[4] Bart De Pontieu (Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, California, United States), Robert Erdélyi and Stewart James (both from the University of Sheffield, United Kingdom) hypothesised in 2004 that spicules form as a result of P-mode oscillations in the Sun's surface, sound waves with a period of about five minutes that causes the Sun's surface to rise and fall at several hundred meters per second (see helioseismology).

Magnetic flux tubes that are tilted away from the vertical can focus and guide the rising material up into the solar atmosphere to form a spicule.