{"dataset":{"slug":"solar-physics","title":"Solar Physics & Heliosphere","description":"The Sun from core to heliosphere — the concentric interior zones and atmosphere layers (solar regions), the surface and atmospheric features (granulation, prominences, filaments, plages, spicules, coronal loops, streamers), and the structures of the heliosphere (Parker spiral, termination shock, heliosheath, bow wave). Reuses the Sun, the space-weather phenomena, and the solar observatories. Only well-established solar physics; nothing fabricated.","version":"1.0.0","lastGenerated":"2026-06-29","license":"CC BY-SA 4.0","entityCount":21,"sources":["nasa","esa"]},"entities":[{"id":"solar_feature:coronal-loop","name":"Coronal Loop","type":"solar_feature","domain":"science","description":"An arch of hot, glowing plasma tracing a magnetic field line rooted in the photosphere, the basic building block of the closed corona above active regions. Coronal loops shine brightly in the extreme ultraviolet and X-rays and are central to studies of how the corona is structured and heated.","entryPath":"/solar-physics/coronal-loop"},{"id":"solar_feature:coronal-streamer","name":"Coronal Streamer","type":"solar_feature","domain":"science","description":"A large, pointed structure in the corona, seen in eclipse and coronagraph images as bright rays extending outward above the streamer belt. Helmet streamers cap closed magnetic regions and are the source of the slow solar wind; their shape changes over the solar cycle.","entryPath":"/solar-physics/coronal-streamer"},{"id":"solar_feature:filament","name":"Filament","type":"solar_feature","domain":"science","description":"The same structure as a prominence, but seen against the bright solar disk rather than at the limb, where it appears as a dark, thread-like channel. A filament is cool plasma along a magnetic boundary; its sudden eruption is a common trigger of a coronal mass ejection.","entryPath":"/solar-physics/filament"},{"id":"solar_feature:granulation","name":"Granulation","type":"solar_feature","domain":"science","description":"The mottled, cellular pattern covering the photosphere — the tops of convection cells about a thousand kilometres across, each lasting only minutes. Bright centres are hot plasma rising, dark lanes are cooler plasma sinking. Granulation is the direct visible signature of the convection zone beneath.","entryPath":"/solar-physics/granulation"},{"id":"solar_feature:plage","name":"Plage","type":"solar_feature","domain":"science","description":"A bright region of the chromosphere associated with an active region, where concentrated magnetic field heats the plasma above a group of sunspots. Plages are conspicuous in the light of hydrogen and calcium and mark magnetically active areas even as the sunspots themselves come and go.","entryPath":"/solar-physics/plage"},{"id":"solar_feature:polar-coronal-plume","name":"Polar Coronal Plume","type":"solar_feature","domain":"science","description":"A thin, ray-like structure of denser plasma rooted in the Sun's polar regions and extending into a polar coronal hole. Plumes trace open magnetic field lines from which fast solar wind flows, and appear as delicate streaks in images of the poles.","entryPath":"/solar-physics/polar-coronal-plume"},{"id":"solar_feature:prominence","name":"Prominence","type":"solar_feature","domain":"science","description":"A large, relatively cool and dense structure of plasma suspended above the solar surface by magnetic fields, extending into the hot corona. Seen at the limb against the dark sky it appears as a bright arch; quiescent prominences can last for months, while eruptive ones can launch a coronal mass ejection.","entryPath":"/solar-physics/prominence"},{"id":"solar_feature:spicule","name":"Spicule","type":"solar_feature","domain":"science","description":"A short-lived jet of plasma, a few hundred kilometres across, that shoots up from the chromosphere at tens of kilometres per second and falls back within minutes. Millions cover the Sun at any moment, giving the chromospheric limb a grassy appearance; they may contribute to the mass and energy budget of the corona.","entryPath":"/solar-physics/spicule"},{"id":"solar_feature:supergranulation","name":"Supergranulation","type":"solar_feature","domain":"science","description":"A larger-scale convective pattern, with cells around thirty thousand kilometres across that persist for roughly a day. Supergranule flows sweep magnetic field to their edges, building the chromospheric network. It was discovered through Doppler measurements of the surface flows.","entryPath":"/solar-physics/supergranulation"},{"id":"solar_region:chromosphere","name":"The Chromosphere","type":"solar_region","domain":"science","description":"The reddish layer of the solar atmosphere just above the photosphere, a few thousand kilometres thick, briefly visible as a rosy rim at the start and end of a total eclipse. Its temperature rises with height, and it is threaded by spicules, filaments, and plages. Above it lies the thin transition region.","entryPath":"/solar-physics/chromosphere"},{"id":"solar_region:convection-zone","name":"The Convection Zone","type":"solar_region","domain":"science","description":"The outer third of the solar interior, where energy is carried by convection — hot plasma rises, cools, and sinks, like a pot of boiling water. This churning is visible at the surface as granulation and drives the magnetic activity of the Sun. It sits above the tachocline and below the photosphere.","entryPath":"/solar-physics/convection-zone"},{"id":"heliosphere_structure:heliosheath","name":"The Heliosheath","type":"heliosphere_structure","domain":"science","description":"The turbulent outer region of the heliosphere, between the termination shock and the heliopause, where the slowed solar wind piles up and is deflected by the interstellar medium. Both Voyager spacecraft spent years traversing it before reaching interstellar space.","entryPath":"/solar-physics/heliosheath"},{"id":"heliosphere_structure:heliospheric-bow-wave","name":"The Heliospheric Bow Wave","type":"heliosphere_structure","domain":"science","description":"The disturbance ahead of the heliosphere as it moves through the surrounding interstellar cloud. Earlier work expected a sharp bow shock, but measurements from IBEX and the Voyagers suggest the Sun moves too slowly through the local medium for a strong shock — a gentler bow wave instead. The exact nature of the boundary is still being studied.","entryPath":"/solar-physics/heliospheric-bow-wave"},{"id":"heliosphere_structure:parker-spiral","name":"The Parker Spiral","type":"heliosphere_structure","domain":"science","description":"The spiral shape the Sun's magnetic field takes as it is carried outward by the solar wind while the Sun rotates, like water from a spinning sprinkler. Predicted by Eugene Parker in 1958 and since confirmed by spacecraft, the Parker spiral sets the geometry of the interplanetary magnetic field and how solar storms reach the planets.","entryPath":"/solar-physics/parker-spiral"},{"id":"solar_region:photosphere","name":"The Photosphere","type":"solar_region","domain":"science","description":"The visible surface of the Sun — the layer from which sunlight escapes — with an effective temperature near 5,772 kelvin and a thickness of only a few hundred kilometres. Sunspots, granulation, and the limb darkening seen in white-light images all belong to the photosphere. It is the reference surface for the Sun's radius.","entryPath":"/solar-physics/photosphere"},{"id":"solar_region:radiative-zone","name":"The Radiative Zone","type":"solar_region","domain":"science","description":"The layer surrounding the core, from about a quarter to seven-tenths of the solar radius, where energy travels outward as radiation. Photons are absorbed and re-emitted so many times that a single packet of energy can take on the order of a hundred thousand years to cross it. The plasma here rotates almost as a rigid body.","entryPath":"/solar-physics/radiative-zone"},{"id":"solar_region:solar-core","name":"The Solar Core","type":"solar_region","domain":"science","description":"The innermost region of the Sun, out to about a quarter of its radius, where nuclear fusion powers the star. At roughly 15 million kelvin and immense density, hydrogen fuses to helium mainly through the proton–proton chain, releasing the energy that slowly works its way outward. Almost all of the Sun's luminosity is generated here.","entryPath":"/solar-physics/solar-core"},{"id":"solar_region:corona","name":"The Solar Corona","type":"solar_region","domain":"science","description":"The Sun's outermost atmosphere — a tenuous, million-degree plasma extending millions of kilometres into space, visible to the eye only during a total solar eclipse or with a coronagraph. Far hotter than the surface beneath it, it is shaped by magnetic fields into loops, holes, and streamers, and it continually expands outward as the solar wind.","entryPath":"/solar-physics/corona"},{"id":"solar_region:tachocline","name":"The Tachocline","type":"solar_region","domain":"science","description":"The thin shear layer near seven-tenths of the solar radius, where the rigidly rotating radiative interior meets the differentially rotating convection zone. This velocity shear is widely thought to be where the Sun's large-scale magnetic field is generated — the seat of the solar dynamo.","entryPath":"/solar-physics/tachocline"},{"id":"heliosphere_structure:termination-shock","name":"The Termination Shock","type":"heliosphere_structure","domain":"science","description":"The boundary where the supersonic solar wind abruptly slows as it runs into the pressure of the interstellar medium, roughly ninety astronomical units from the Sun. Voyager 1 crossed it in 2004 and Voyager 2 in 2007 — the first direct measurements of this shock.","entryPath":"/solar-physics/termination-shock"},{"id":"solar_region:transition-region","name":"The Transition Region","type":"solar_region","domain":"science","description":"The thin, irregular layer between the chromosphere and the corona where the temperature climbs steeply — from around ten thousand to a million kelvin over only a few hundred kilometres. It radiates mostly in the extreme ultraviolet and is central to the still-open question of how the corona is heated.","entryPath":"/solar-physics/transition-region"}]}