Science & history · Inside and above
Above the surface: the chromosphere and its spicules
Above the photosphere is a thinner, hotter layer, the chromosphere, bristling with jets called spicules.
Spicules
NASA describes spicules as jets that shoot up as fast as 100 kilometres per second and reach about 9,700 kilometres: almost Earth's diameter, in a few minutes.
Into the corona
The chromosphere heats up rapidly into the corona. NASA notes that not all scientists treat the transition region as a layer of its own: it is the thin zone where that sudden heating happens.
Sources
- NASA Sun: Facts (opens in a new tab) for age, size, distance, temperatures, layers, rotation, cycle, type, future · checked 2 October 2026