What are spicules? Dr. Luc Rouppe van der Voort (ITA, University of Oslo), explains.
Spicules close to the solar limb observed with the SST. / Credit: Luc Rouppe van der Voort (ITA, University of Oslo).
Spicules are thin, elongated jets a few hundred kilometers wide. They reach up to 6000 km height and can move at speeds of more than 100 km/s. Spicules are found all over the solar surface, but can be observed most easily near the limb of the Sun. Discovered by Father Angelo Secchi in the 19th century, scientists are still debating their origin. We need the extreme capabilities of the European Solar Telescope in order to fully understand the role of spicules in the mass transport and heating of the outer solar atmosphere.
The figure shows spicules close to the solar limb in the red wing of the H-alpha spectral line, as observed with the SOUP instrument at the Swedish 1-meter Solar Telescope on La Palma (Spain).