A comet nucleus is a "dirty snowball" of ice and dust. As it nears the Sun, absorbed sunlight sublimates surface ice directly into gas, which drags dust off the nucleus through active vents (jets) and forms the coma and two tails.
T_eq ≈ 278 K / √d (equilibrium blackbody temperature, d in AU)
Ṁ ∝ jets · exp(-k/d) (sublimation rate rises sharply inside ~2.5 AU)
Dust tail: curves — inherits some orbital velocity, pushed by radiation pressure
Ion tail: straight — locked to the solar-wind field, always points anti-sunward
- Heliocentric distance — sets sunlight flux, surface temperature and how fast ice sublimates.
- Rotation period — how fast the nucleus spins, sweeping its active vents in and out of sunlight.
- Active jets — number of vents currently venting gas and dust; more jets, denser coma and tails.
- Solar wind strength — how hard the ion tail is stretched and accelerated anti-sunward.
- Tails toggle — isolate the dust tail (curved, reflects sunlight) or the ion tail (straight, fluoresces blue) to compare their different physics.
Real-world relevance: this is exactly how mission teams like ESA's Rosetta plan flybys — activity forecasts from this kind of distance/temperature model decide how close a spacecraft can safely fly through the coma.