<P> In solar physics, a spicule is a dynamic jet of about 500 km diameter in the chromosphere of the Sun . It moves upwards at about 20 km / s from the photosphere . They were discovered in 1877 by Father Angelo Secchi of the Observatory of Roman Collegium in Rome . </P> <P> Spicules last for about 15 minutes; at the solar limb they appear elongated (if seen on the disk, they are known as "mottles" or "fibrils"). They are usually associated with regions of high magnetic flux; their mass flux is about 100 times that of the solar wind . They rise at a rate of 20 km / s (or 72,000 km / h) and can reach several thousand kilometers in height before collapsing and fading away . </P>

Where do spicules tend to occur on the sun