Blackbody Glow (Colour Temperature)
Heat an object toward a chosen target temperature and watch it glow the colour a real blackbody emits — deep red to blue-white — while its radiated power rises steeply with temperature.
Preview — sign up free to change the numbers yourself
What you can adjust
- Target temperature
- 500 – 40000 K
- Starting temperature
- 300 – 2000 K
- Heating time constant
- 0.3 – 10 s
- Emissivity
- 0 – 1
The temperature the object heats toward — like an incandescent bulb filament (~3000K default), a dull red-hot poker (~500K), or a hot blue-white star (~40000K). Higher = bluer glow, much more radiated power.
Room temperature by default. Must be below the target — the object always heats up, never cools.
Roughly how long the object takes to substantially heat up — smaller means faster (a blowtorch); larger means slower (a kiln). The object reaches ~99% of the target after about 4.6x this time.
1 = ideal blackbody radiator. Lower values radiate less power at the same temperature (a duller real-world emitter).
About this simulation
What it shows
An object heats up from a starting temperature towards a target and glows the colour a real hot object gives off, from dull red through orange and yellow to white and blue-white. A readout gives its temperature and the wavelength where it radiates most.
The key idea
Hotter objects glow bluer, because the wavelength of peak emission gets shorter as temperature rises. The power they radiate rises with the fourth power of the temperature (P ∝ T⁴), so doubling it gives 16 times the power.
Try this
Set Target temperature to 3000 K and then 6000 K: the glow shifts towards white and the radiated power is 16 times greater.
The object always heats towards the target and never overshoots, and Emissivity below 1 makes it a duller emitter than an ideal one.